A TEN YEAR RETROSPECTIVE STUDY ON ENCEPHALOCELES AS SEEN AND MANAGED AT KENYATTA NATIONAL HOSPITAL (JANUARY 1992-DECEMBER 2001)

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1 A TEN YEAR RETROSPECTIVE STUDY ON ENCEPHALOCELES AS SEEN AND MANAGED AT KENYATTA NATIONAL HOSPITAL (JANUARY 1992-DECEMBER 2001) BY DR. NYAGAH ROBERT WAMAE (MB.ChB) A DISSERTATION SUBMITTED IN PART FULFILLMENT FOR THE DEGREE OF MASTER OF MEDICINE (SURGERY) OF THE UNIVERSITY OF NAIROBI NOVEMBER 2002

2 DECLARATION This dissertation is my original work and has not been presented for a degree in any other university or for publication in any journal. Signed.. DR. NYAGAH ROBERT WAMAE, MB.ChB (Nairobi) Date This dissertation has been submitted with my approval as a university supervisor. Signed. Date. PROFESSOR N. J. M. MWANG OMBE MBChB, M.Med (SURGERY). Ph.D. (London) CONSULTANT NEUROSURGEON (KNH) ASSOCIATE PROFESSOR, DEPARTMENT OF SURGERY UNIVERSITY OF NAIROBI 2

3 DEDICATION This work is dedicated to my late mother Elizabeth Waithera, who encouraged me in times of hardship and also instilled the principles of hard work in me as l grew up. 3

4 ACKNOWLEDGEMENT I am greatly indebted to my supervisor Prof. N. J. M. Mwango mbe for his assistance, advise and critique, both as a teacher and a friend, which led to the success of this study. My wife, Gertrude and my children, Brenda, Damaris, Laura and Charlotte who tolerated without complaint the long hours l spent in the library preparing this dissertation. I shall always be grateful to them for their patience and endurance. Special appreciation and gratitude to Bishop Philip Sulumeti for the full sponsorship for this program. My sincere gratitude goes to the Kenyatta National Hospital Ethical and Research Committee and the staff of the Records Department of KNH for their help in file retrieval. To the University of Nairobi for accepting me into the program and for the training, l shall always be grateful. 4

5 CONTENTS Page 1. Title Declaration 2 3. Dedication Acknowledgement 4 5. Contents 5 6. List of tables List of figures Abbreviations Summary Introduction Literature review Objectives of the study Rationale of study Materials and methods Results Discussion References Appendix 1 (proforma Questionnaire) Appendix 2 (Ethical and Research Committee- Approval letter) 90 5

6 LIST OF TABLES Page Table 1 Gender distribution. 30 Table 2 Source of referrals of the study cases. 31 Table 3 Yearly distribution of patients 32 Table 4 Age distribution of patients at the time of presentation.. 33 and surgery Table 5 Time interval between diagnosis and surgery 34 Table 6 Tribal distribution by diagnosis. 35 Table 7 Findings on local examination of encephaloceles. 36 Table 8 Condition of skin cover versus surgical complications. 37 Table 9 Associated congenital anomalies 38 Table 10 Special investigations done Table 11 Associated conditions at presentation.. 43 Table 12 Distribution of the lesions according to site. 44 Table 13 Surgical treatment. 45 Table 14 Surgery for VP shunts insertion 47 Table 15 Interval between repair and VP shunt surgery. 48 Table 16 Post operative hospital stay. 49 Table 17 Duration of admission.. 50 Table 18 Follow up after surgery 51 Table 19 Surgical complications by age.. 52 Table 20 Complications of surgery. 53 Table 21 Recurrence of anterior encephaloceles. 54 Table 22 Recurrence of all encephaloceles. 54 Table 23 Mortality among the study cases

7 LIST OF FIGURES Page Figure 1 Gender distribution.30 Figure 2 Type of delivery..39 Figure 3 Duration of pregnancy.40 Figure 4 Family history of encephalocele..41 Figure 5 Surgical approach in repair..45 Figure 6 Excision of neural tissue 46 7

8 ABBREVIATIONS U/S Ultra Sound CT Scan Computerized Tomography MRI Magnetic Resonance Imaging KNH. Kenyatta National Hospital VPS Ventriculo Peritoneal Shunt Post OP.. Post operative CSF Cerebro spinal fluid N/A. Not Applicable SVD.. Spontaneous Vertex Delivery PRE OP.. Pre-operative INTRA OP Intra operative CNS. Central Nervous System. 8

9 SUMMARY This is a retrospective study of patients with cranial encephaloceles seen at the Kenyatta National Hospital over a period of ten years from 1 st January 1992 to 31 st December Eighty-nine patients with cranial encephaloceles were treated at the Kenyatta National Hospital during that period. There were 31 males (34.8%) and 58 females (65.2%). Seventy-one patients (79.8%) were referrals from other health care providing services. District hospitals contributed the most, 38.2% of the patients. The youngest patient was 1 day old and the oldest was 10 years with a mean age distribution of 5.25 months and a median of 1.5 months. The commonest age group to be operated on was between 1 month to 6 months (39.3%) with the mode being 3 months (16.9%). The Kikuyu with 41.6% and Kamba with 14.6% were the commonest tribes followed by the Luhya 11.2%, Meru 9.0%, Kalenjin 6.7%, Luo 4.5% and all the remaining other tribes accounting for 16.9%. Eight percent of the patients presented with leakage of cerebrospinal fluid (CSF) from the encephalocele and seventeen percent of all patients had ulceration of the lesion. The commonest associated congenital malformation was hydrocephalus which was observed in 19% of the patients. Other associated congenital malformations of the CNS were cranio vertebral junction anomalies, Dandy walker cyst and microcephaly.fifty seven percent of the patients did not have any obvious associated congenital malformations. 9

10 Computerized Tomography (CT Scan) of the head was the commonest imaging study done (42.7%), followed by ultrasonography (15.7%) and radiography (14.6%). Sixty one percent of the study cases had posterior encephaloceles with anterior lesions accounting for 39%. All the patients with posterior encephaloceles underwent excision and repair of the lesion, while 69% of the patients with anterior encephaloceles underwent extracranial excision and repair. Thirty one percent of the patients with anterior encephaloceles underwent intracranial excision and repair of the lesion. VP shunting alone without excision of the lesion was performed on one patient with anterior encephaloceles. Thirty three percent of those with posterior encephaloceles had surgery for insertion of VP shunts while for anterior lesions it was 34.4%. The commonest complications seen in patients who underwent surgery for cranial encephaloceles were wound infection (19.1%), intra-operative hemorrhage (18%) and recurrence of the lesion (12%). Eight patients (9%) died following surgery, with four (4) of these dying within 6 weeks of surgery. The average duration of hospital stay was 46 days although the average post- operative hospital stay was 14 days. Most of the patients (76.4%) attended the outpatient clinic regularly for review for at least 12 months. 10

11 INTRODUCTION Definitions Encephalocele: Encephalocele is a congenital malformation of the central nervous system in which cerebral tissue and meninges in communication with cerebrospinal fluid (CSF) pathways herniate through a defect in the cranium. If cranial herniation contains only CSF and meninges it is a meningocele. It is a meningoencephalocele when it contains both the meninges and neural tissue. The cranial herniation is a hydromeningo encephalocele when it contains the meninges, neural tissue and a portion of the ventricular system. The term encephalocele is used frequently to include all these lesions because earlier before current imaging techniques became available, it was not possible to distinguish between the different forms before surgery. (1). Encephaloceles may occur posteriorly, anteriorly, laterally, in the vault, or in the base of the skull. Encephaloceles are common in the African and Oriental races and rare in Caucasians (2). Occipital lesions predominate in most series reported in Africa, except in South Africa where occipital and frontal lesions enjoy equal distribution (3). Cranial dysraphisms are not as common as spinal dysraphisms being only 10 to 20% as common as spinal dysraphisms. (4) (5) The incidence of occipital encephaloceles in Caucasians is 1 in every 5000 live births (6), while that of frontal encephaloceles is 1 in every live births (7). The birth of a baby with an encephalocele is usually distressing to the parents and 11

12 inflicts much psychological trauma to them. The unsightly and disfiguring swelling on the head or face and the risk of associated brain damage in these children further adds to the stress on the parents. Asymptomatic basal encephaloceles may present in adulthood as space occupying lesions, CSF leak due to fistula formation or recurrent meningitis (8). Usually the neural tissue within the encephalocele is dysplastic but occasionally it may be functional and associated with mental retardation, blindness, convulsions or neurological deficits. All cases, except those with obvious gross brain damage, should be operated, therefore, approximately 80-85% of patients with encephaloceles can be treated surgically. Over 50% of infants with posterior encephaloceles develop hydrocephalus following surgery (5). Decisions on whether to operate or not, may be influenced by the presence and severity of additional congenital anomalies. A second neural tube defect is found in 15-20% of patients. (9) Repair of an encephalocele is essential to permit reasonable nursing and custodial care. Long-term follow-up is necessary in all cases as these patients have a high risk of developing hydrocephalus following surgery. 12

13 LITERATURE REVIEW Historical Background Hippocrates in B.C. may have been referring to hydrocephalus or encephaloceles when he recognised that water accumulating in the head caused it to swell. He may have performed a puncture of the swelling for its treatment (4). Around the same period, Oribasius (4) mentioned cases in which fluid accumulated over the surface of the brain but he did not mention enlargement of the ventricles. It was not until the 7 th century (4) that Paul of Aegena confirmed these findings and mentioned use of trephination in its treatment, although he did not personally favor it. Richter published the first case of anterior encephalocele in 1813 (10) and after that it was known that encephaloceles could occur at different sites. Fifteen years later Geoffrey Saint - Hilaire published his theory in which he attributed anterior encephaloceles to adhesions between brain dura and overlying skin resulting in a localized interference with the development of the bone vault (11). A century later Sternberg (12) provided support for Saint Hillaires theory on embryological grounds. He theorized that failure of the anterior neuropore to close at end of the 3 rd week of development prohibited invasion of mesoderm into the midline of the embryo resulting in a failure of skull formation in the overlying calvaria. This theory ascribes aetiology to neuroectodermal maldevelopment. Klementowski thought that bone maldevelopment from syphilis and rickets was responsible for this disorder (12). Report of successful resection of a frontal protrusion by Cornivius appeared in 1755 (13). Since 1892 Bayer and others excised encephaloceles with encouraging results and, together with others like Von Bergman (1899), Brodmann in 1911 and Frazier in 1918 their efforts are 13

14 responsible for the evolution into the present-day techniques of encephalocele and spina bifida repair (4,14). Fenger in 1895 (15) performed successfully the first reported operation for intranasal encephalomeningocele, which he resected through the transmaxillary route. Techniques of encephaloceles repair have been evolving since then. Classification of anterior encephaloceles was first done by Masterton (13) in 1855 who classified 19 cases into naso-frontal, naso-ethmoidal and naso-orbital depending on the external orifice of the skull defects. In 1903 Stadfelt reported that all the three types previously described had the same internal orifice inside the cranium, at the site of the foramen caecum, and hence termed them 'frontoethmoidal' encephaloceles (13). Classification of Encephaloceles Encephaloceles are classified according to either the location of the mass on the head, the contents of the sac and the site of the defect in the cranium. Location: This is a useful classification for the initial description of the mass. The lesion may be described as occipital, sincipital, parietal, basal, vertical and nasofrontal. Contents of the Sac: This classification was previously thought to be unsatisfactory because a detailed histological examination was usually necessary. However with the recent advances in imaging techniques (1), it is possible to differentiate them preoperatively into meningoceles, meningoencephaloceles and hydromeningoencephaloceles. 14

15 Location of skull defect: This is the most practical classification as it is useful for the planning of surgery. The method proposed by Suwanwela and Suwanwela (1972) (16) is: 1. Occipital 2. Cranial vault - Interfrontal - Anterior fontanelle - Inter parietal - Posterior fontanelle - Temporal 3. Fronto ethmoidal - Nasofrontal - Naso Orbital - Naso ethmoidal 4. Basal - Transethmoidal - Sphenoethmoidal - Trans sphenoidal Another method that has been found to be easier to apply clinically is to group encephaloceles into: (i) Posterior lesions - includes occipital, interparietal and suboccipital lesions, and (ii) Anterior lesions - which may be further classified into 3 categories, namely (a) (b) (c) Frontal - includes anterior fontanel and interfrontal, Sincipital (located about midface) nasofrontal, naso-orbital, nasoethmoidal and Basal (at the base of the skull) 15

16 transethmoidal, transsphenoidal, trans spheno ethmoidal POSTERIOR ENCEPHALOCELES: This includes occipital, sub occipital and interparietal lesions. The incidence of occipital encephaloceles among Caucasians is 1 in every 5000 live births (6). In Nigeria, occipital lesions account for 70-80% of all encephaloceles, while frontal lesions account for less than 20% (17). Parietal lesions are rarer (5-10%). Similar findings have been reported in studies from the Western hemisphere where 85% of the lesions are located posteriorly (16). Occipital lesions occur in the midline. They may be pedunculated or sessile depending on whether the bone defect is small or large respectively. They vary in size and shape and may be even larger than the head especially when associated with microcephaly. These lesions present at birth as a tense, rounded swelling at the occipital, interparietal or suboccipital region. The swelling is usually cystic and may be translucent. Skin cover may range from a full thickness scalp to a thin membrane derived from meninges fused with thin skin at the dome. Often there are vascular abnormalities of the scalp, overlying and adjacent to the sac. Pressure on the encephalocele is usually readily transmitted to the anterior fontanel and vice verse (18). Where the cranial defect is small and becomes sealed by the growing skull by the time of presentation, this transmission of pressure is absent (19). Hair adjacent to the lesion may be unusually long and silky in the caucasians. 16

17 The size of the mass does not always correlate with the contents of the sac or the size of the cranial defect. Where there is neural tissue within the sac, palpation of the sac will demonstrate the solid tissues. Trans-illumination of the lesion in a completely dark room using a strong light source is helpful in outlining the contents of the lesion and ruling out the presence of neural tissue. Usually, a neurological examination is within normal limits in a newborn infant with a posterior encephalocele except where there are other associated anomalies. Occipital and suboccipital encephaloceles are frequently associated with hindbrain malformations (20), which cause obstruction to CSF flow leading to hydrocephalus. Approximately 25% of patients with occipital and suboccipital encephaloceles have an obvious microcephalus with gross malformations of the brain (5). Hydrocephalus develops in over 50% of infants with encephaloceles. (21,22) ANTERIOR ENCEPHALOCELES There are 3 categories of anterior lesions namely: (i) Frontal - Anterior fontanel Interfrontal (ii) Sincipital - (Are located about midface) - Nasofrontal (at midline, root of nose) - Naso-orbital (anteromedial portion of orbit) - Nasoethmoidal (on side of nose) (iii) Basal - (Are at the base of the skull) 17

18 - Transethmoidal - Transsphenoethmoidal - Transsphenoidal The anterior encephaloceles are also commonly referred to as frontal encephaloceles (23). These lesions are rare in caucasians where an incidence of 1 in every live births has been reported. (7). In Thailand, the incidence of frontal encephaloceles has been reported as 1 in 5000 births. There is a higher incidence among Mongolian peoples, which has been attributed by some to the fact that the base of their nose is flat and broad. Most of the anterior lesions reported by Suwanwella (24) were fronto-ethmoidal in location. Generally 6-12% of all meningoencephaloceles appear in an anterior location (25), among the Mongolian people Despite the unusual geographical distribution of anterior encephaloceles, there does not appear to be any pattern of genetic inheritance or environmental factors affecting their incidence (26). For anterior basal encephaloceles, the more posterior the encephalocele is located, the less frequent it is, but the more vital are the structures involved. Clinical presentation of anterior encephaloceles varies according to the category of the encephalocele. They may present at birth with an obvious swelling in which case the diagnosis may be obvious or presentation may be unique requiring investigations to make a diagnosis. Cranio-facial disruption varies from minimal to massive. Ulceration of the lesion may lead to CSF leak and meningitis. Frontal lesions 18

19 These usually present as a cystic swelling on the frontal aspect of the face, usually in the midline. Their appearance at birth may be terrifying but usually carry a better prognosis than posterior lesions. This is because they are often smaller extrusions with little dysplastic neural tissue, if any, compared to the posterior lesions. Frontal lesions are also less often associated with hydrocephalus. Other associated clinical features may include seizures, presence of midline skeletal defects like cleft lip and/or palate, brain tissue involvement (usually from relatively silent areas of the frontal lobe), hydrocephalus and spina bifida. Sincipital Lesions These present as single or multiple swellings at the bregma or nasion. Displacement of lacrimal and nasal bones may cause epiphora. Nasofrontal type The defect is between the frontal and nasal bones. The dura herniates through defect in the fronto-ethmoidal junction causing downward displacement of nasal bones and lateral displacement of the medial orbital walls. Nasoethmoidal The defect is between the nasal bone and the nasal cartilages. The dura herniates through a defect between the frontal and ethmoidal bones. The lesion protrudes extra-cranially below the nasal bone. Naso Orbital type The defect is in the medial orbital wall between the lacrimal bone and frontal process of maxilla. The lesion exits at the medial orbital walls. The lesion presents as a mass between the nose and the lower eyelids. Basal Lesions: The clinical features are determined by the location of the bony defect. The meninges herniate through the cribriform plate into the nasal cavity between the 19

20 middle turbinate bone and the nasal septum or into the nasopharynx. In the neonatal/infantile period, allied congenital malformations of the face, eyes and brain are a clue to diagnosis of basal encephaloceles. Adulthood diagnosis is suspected from visual disturbances, pituitary - hypothalamic dysfunction or CSF rhinorrhoea (27), if there is no mid-facial abnormality nor respiratory difficulties (28). They may present with recurrent meningitis. PATHOGENESIS OF ENCEPHALOCELES The pathogenesis of encephaloceles is not well established but there are various theories as summarized by Mood and Pollock (29,30,31). Theories that have been put forward are: Non-separation Theory In this theory it is assumed that there is failure of separation of neuroectoderm from surface ectoderm at the anterior neuropore, ventrally, where neural tube closes last towards end of fourth week gestation. This failure of separation causes the neuroectoderm of subsequent diencephalic vesicle to remain in contact with the ectoderm of the subsequent primitive oral cavity (Stomodeum) preventing subsequent development of mesodermal elements, which later form the skull. Craniopharyngeal canal persistent Theory: Normally, the Rathke's pouch arises from the primitive oral cavity and grows towards the brain just rostral to the tip of the notochord and comes into contact with an evagination of the diencephalic floor, the infundibulum, by fifth week 20

21 of gestation. Upon regression of the stalk of Rathke's pouch, hypophyseal cartilages appear as a pair of chondrification centres at the sixth week, flanking the craniopharyngeal duct representing the tract of the Rathke's pouch, and they fuse in the following week to form body of the sphenoid bone (32). If the stalk of Rathke's pouch (Craniopharyngeal duct) persists, the diencephalic floor may bulge down through the canal, and structures lying in the anterior diencephalic ventricle i.e. optic stalk, optic chiasma and the commisural plate, may be involved in the herniated encephalocele. Failed fusion of the sphenoid bone complex by this period will provide mesenchymal growth vectors in the medial nasal and maxillary process, giving rise to facial clefting (33). Anomalies of face, optic system and brain concomitant with transsphenoidal encephalocele are assumed to be formed together in the same stage in embryonic period and to arise from neighbouring areas in ventral surface of the cephalic end of neural tube around the anterior neuropore. Trans-ethmoidal encephaloceles are rarely associated with optic or cerebral malformations and are therefore assumed to occur in later embryogenesis and via a different pathogenesis than trans-sphenoidal. Transethmoidal encephaloceles also develops through a unilateral defect of cribriform plate in presence of crista galli, which is formed in later fetal period. INVESTIGATIONS OF ENCEPHALOCELES: Whereas making a diagnosis of encephalocele may not be difficult, proper investigations of the lesion is invaluable in formulating strategy of reconstructive surgery and pre-empting possible complications. i) Radiological: Plain skull radiographs and/or cranial tomography - this outlines cranial defects and sinuses. They also show orbital alignment. 21

22 ii) Ultrasound: Has limited role in diagnostic evaluation of a neonate. Cranial ultrasound detects presence of hydrocephalus, contents of the swelling. Ultrasound may diagnose encephaloceles in utero especially the posterior ones. iii) Magnetic Resonance Imaging: Is the best technique in investigating an encephalocele but is expensive and not always available. Magnetic Resonance Angiography - shows the location of both venous and arterial structures within an encephalocele. Its use is not yet common in our set-up. It is also very expensive. iv) Computed Tomography: This is second to MRI in superiority. It is more available and affordable and it gives enough details for accurate classification and management of encephaloceles. v) Other investigations worth mentioning for their historical importance are. air ventriculography, vertebral angiography and pneumoencephalography SURGERY OF ENCEPHALOCELES Almost all encephaloceles should be repaired except where there is gross brain damage where terminal care is adequate (18). For asymptomatic trans sphenoidal encephalocele of the so-called 'adult type' in which the patient will survive without grave endocrinological or visual disturbance, operation may not be necessary (34,35) and is actually discouraged. 22

23 Surgery for encephaloceles should ideally be done in the postnatal period. Removal of the mass improves the physical appearance and also permits reasonable nursing and custodial care of the baby. Neck support is improved and the risks of ulceration and trauma to the lesion with subsequent meningitis is drastically reduced. Aim of Surgery: Early repair in a patient fit to withstand the operation. Aims of the surgery are: i) Exposure of the cranial defect through a planned incision or approach. ii) Excision of herniated dysplastic brain tissue iii) Tension free repair of the dura iv) Cranial base or cranium repair v) Repair of overlying soft tissues free of tension. vi) Craniofacial reconstruction where necessary. Surgical Approaches The approach used in surgery depends on the type or site of encephalocele and the surgeon's preference and/or experience. The different approaches are: i) Extra cranial approach: Used for all posterior encephaloceles and small frontal encephaloceles. Associated with many complications if used for repair of basal encephaloceles. This approach allows easy access to the bony defect ii) Intracranial approach 23

24 Involves craniotomy through either a unilateral frontal bone flap extending to midline or through bilateral frontal flaps. Neck of protruding brain is exposed either extra-duraly or intra-duraly by retracting the frontal lobes gently (4,18,36). This approach is indicated for all basal lesions, huge frontal encephaloceles and nasal encephaloceles (37). Although this approach is technically more demanding than extracranial, it is associated with a less post-operative complication rate. For these lesions this approach is more superior to extracranial approach. Redundant meningocele sac protruding into nose and pharynx is left alone to shrivel if empty and dura tightly closed. Reconstructive surgery is done later if indicated, thus, if the sac persists or the facial deformity is marked. Current recommendation for the management of nasal encephaloceles is to do a one stage definitive technique through intracranial repair by the neurosurgeon while the maxillofacial surgeon extracranially reconstructs the face (38,39). Other methods that have been tried but not yet common include: (iii) Endoscopic transnasal approach (iv) External ethmoidectomy (v) Trans-oral trans-palatal approach - for sphenoethmoidal encephaloceles in- patients with cleft palate (40). 24

25 (vi) Trans-sphenoidal approach for trans-sphenoidal encephaloceles. This approach may be combined with trans-cranial approach which is a superior method (41). Complications of Surgery Common complications of these surgeries are hydrocephalus, haemorrhage, infections (wound infection, meningitis) and CSF leakage from site of repair. Hydrocephalus occurs in about 50% of all posterior encephaloceles following their excision and repair. (21,5). Postoperative hydrocephalus is more common with meningoencephalocele than meningocele and causes compromise of wound closure therefore necessitating a shunting procedure for the CSF. The other known complications include air embolism, resection of functional neurological tissues with subsequent neurological deficit or seizures. Brain stem damage in subtorcular encephalocele may lead to inability to extubate, while ablation of occipital lobes in posterior encephaloceles almost inevitably leads to blindness. Pre-operative preparation for surgery includes a thorough assessment of the patient's lesion and determination of fitness to undergo the surgery. A thorough physical examination of the patient is mandatory, as associated congenital malformations are common. 25

26 OBJECTIVES OF THE STUDY MAIN OBJECTIVES To determine the outcome in patients with encephaloceles managed by surgery at the Kenyatta National Hospital within the study period. SPECIFIC OBJECTIVES (i) To study the age at presentation and repair of encephaloceles over the study period. (ii) To study the clinical presentation of encephaloceles. (iii) (iv) (v) To study the diagnostic methods used. To evaluate the surgical treatment of encephaloceles To study the incidence of complications following surgery for encephaloceles.. 26

27 RATIONALE OF STUDY Encephaloceles are some of the congenital malformations of the CNS seen at the neurosurgical unit of Kenyatta National Hospital (KNH), a national referral hospital in Kenya serving a population of about 35 million people. No study has been done to determine the outcome of patients managed surgically for this condition. This study aims at reviewing the pattern of presentation and the surgical outcome of patients operated from 1 st January 1992 to 31 st December 2001 at KNH. The results of this study will give a general overview of the management of encephaloceles at KNH and highlight the magnitude of this problem. The data obtained will form a reference point for future research and in evaluation of improvement in the management of this condition. 27

28 PATIENTS AND METHODS Study design: A descriptive retrospective study was conducted between January 1992 and December The study population was all the patients with encephaloceles seen at the neurosurgery clinic and neurosurgery ward of KNH during the study period who underwent surgery. Classification of patients as per the site of encephalocele and mode of management was done for all these patients. In the study group, the numbers of those who did not develop any complications and those who did, following surgery of the encephaloceles, were noted. Mortality and recurrence among the study population was also noted. Study Site The study was carried out at KNH, the country's main referral hospital and teaching hospital for the University of Nairobi. Study type This was a hospital based retrospective study covering ten years from 1 st January 1992 to 31 st December Study Plan The study subjects were identified from the main theatre operation register and their case notes retrieved from the Medical Records Department. A proforma questionnaire was used to record all the required information. A specimen of which is annexed as appendix 1. Inclusion criteria All cases that were recorded as having encephaloceles and underwent surgical repair of the same, during the study period. Exclusion criteria 28

29 The patients excluded from the study were: (a) All those with encephaloceles who did not undergo surgical repair. (b) Those with encephaloceles but were not operated within the study period. (c) Case files with incomplete or inadequate information for the purpose of analysis and the lost files. Ethical Aspects Upon approval by the Ethical and Research Committee of Kenyatta National Hospital, the case notes were retrieved from the records department of KNH and the research carried out in strict confidence by the author. Data Collection Information was collected as per: Age, sex, tribe, presenting symptoms, location of swelling, investigations done, management instituted and complications following surgery. Duration of hospital stay and follow- up upon discharge from the ward was noted. Follow-up period was the time from operation to time of data collection in this research. Data Analysis The data collected was entered into the SPSS-version 9 computer software program for processing. The Fishers exact test and Pearson chi square tests were used to determine statistical significance where indicated (p value of <0.05 was taken as statistically significant). The results are available in tables and charts. Study Limitations 1. Lack of standardization: a) Clinical Assessment was subjective and prone to bias 29

30 b) Reporting of some investigations done like ultrasound and x-rays, were operator dependent. 2. Patients with encephaloceles did not all undergo the same investigations due to the high cost of the investigations and lack of a laid down protocol for these patients. 3. Changes in medical 'tools': Patients managed in the early 90s' did not benefit from the newer and more accurate investigation tools such as ultrasound, CT scans and MRIs' as these were not as readily available. 4. This being a retrospective study it relied heavily on pre-recorded information, which may have been inaccurate, incomplete or omitted. 5. Some of the patient s records were missing from the shelves. 30

31 RESULTS Figure 1 Pie chart showing gender distribution of patients with encephaloceles. GENDER DISTRIBUTION Female (58) 65% Male(31) 35% Male Female There were 58 females (65.2%) and 31 males (34.8%) (figure 1.) Male to Female (M: F) ratio 1:1.9. Table 1 Sex distribution in patients with cranial encephaloceles (n = 89) Sex Encephalocele Posterior Anterior Total (%) Male 17(54.8%) 14(45.2%) 31(34.8%) Female 37(63.8%) 21(36.2%) 58(65.2%) Total (100%) 31

32 Thirty six percent of all female patients had anterior encephaloceles, while 45% of all male patients had anterior encephaloceles. A total of 89 patients underwent surgery for encephaloceles between January 1992 and December All patients were operated upon by surgeons from the neurosurgical unit of KNH. Most of these cases were referred to KNH for management and the contributing health facilities were as shown in (Table 2). Table 2. Health facilities that referred patients in the study to KNH and the proportions of the total cases. Referral centre Frequency Percentage (%) District Hospital Provincial Hospital Mission Hospital Private Clinic Flying Doctors Not referred Total

33 The highest number of patients operated in a year was 12(13.5%) in 1997 while the lowest was 2 (2.2%) in The yearly distribution of patients operated was fairly constant over the study period except in the years 1994,1996 and 1998 when these numbers were lower.(table 3) Table 3 Yearly distribution of patients operated at KNH Year of operation No. of patients Percentage (%) operated Total

34 Table 4 Age distribution of the patients at the time of presentation and surgery. (n = 89) Age No. of patients seen No. of patients operated 0-1 month 44(49.4%) 9(10.1%) > 1-6 months 26(29.3%) 35(39.3%) > 6-12 months 12(13.5%) 18(20.3%) > 12 months 7(7.9%) 27(30.4%) Total The peak age at presentation was those aged up to 1 month (49.4%). The oldest age at presentation was 10 years while the youngest was 1 day old. The youngest patient to be operated was 3 days old while the oldest was 10 34

35 years. Majority of the patients operated were in the age group of 1 to 6 months (39.3%). Those younger than 1 month (10.1%) constituted the least number of patients operated. (Table 4) 35

36 Table 5. Time interval between diagnosis and surgery. Time interval in months Number of patients (%) 0-1 month 25(28.1%) > 1-6 months 40(44.9) > 6-12 months 10(11.3%) > 12 months 14(15.7%) Total 89 The interval between presentation and operation ranged between 0 and 47.7 months. The commonest interval was that between 1 to 6 months (44.9%). (Table 5) Of Kenya s 43 or so tribes, the study has categorized the cases in ten groups and the results shown in table 6. Table 6 Tribe distribution by diagnosis (n = 89) Tribe No. of Patients Posterior Anterior Total No. % lesions lesions Kikuyu (41.6%) Kamba (14.6%) Luhya (11.2%) 36

37 Taita 1 1 2(2.2%) Kisii 2 3 5(5.6%) Meru 2 4 8(9.0%) Luo 4 0 4(4.5%) Somali 1 1 2(2.2%) Kalenjin 2 4 6(6.7%) Masaai 1 0 1(1.1%) Miji Kenda 0 1 1(1.1%)15 Total (100%) The Kikuyu and Kamba tribes constituted 41.7% and 14.6% of the cases respectively and were the largest groups. The other tribes represented occurred in lower frequencies and combined together accounted for 43.8% of the study cases. 37

38 Table 7 Findings on local examination of the swelling (n=65) Findings on the swelling Frequency (%) Ulcerated skin 15 (16.9%) Thin skin 29 (32.6%) Normal thickness skin 36 (40.4%) CSF leak 7 (7.9%) Skin condition not indicated 24 (27%) On local examination of the encephalocele, 36 patients (40.4%) had normal thickness skin cover while in 15 (16.9%) the skin was ulcerated. Condition of the covering skin was not indicated in 24 (27%) patients while 29 patients (32.6%) had thin skin. CSF leak was noted in 7 (7.9%).(Table 7) 38

39 Table 8. Condition of skin cover of encephalocele versus surgical complications. Skin cover of encephalocele Normal skin Thin skin Ulcerated skin Thin and ulcerated skin Not indicated NONE Complications Wound complications Osteomyelitis 1 Meningitis Ventriculitis 1 Others Wound complications were the most common complications following surgery, observed in 19.1% of the patients (Table 8, Table 20). Chi square was not valid. There was no association between condition of skin cover at presentation and the complication rate following surgery. 39

40 Table 9. Associated congenital malformations Associated congenital malformations No. of Percentage patients Hydrocephalus Microcephaly Craniosynostosis Down s syndrome Amelia Nasal meatal defect Dandy walker cyst Atrial septal defect Syndactyly of all toes Arnold chiari malformation Bilateral inguinal hernia None There were no associated malformations in 51 (57.3%) patients. The commonest associated malformation was hydrocephalus found in 17 (19.1%) followed by microcephaly 7 (7.9%) and craniosynostosis in 4 patients (4.5%). Other malformations that occurred in low frequency (1 each) are shown on table 9. 40

41 Figure 2 Type of Delivery Type of delivery Caesarean section Breech 3% 1% Missing 24% SVD 72% Sixty four patients (71.9%) were born by SVD, 3 (3.4%) through cesarean section and breech delivery 1 (1.1%). Mode of delivery of 21 (23.6%) patients was not known. (Figure 2) 41

42 Figure 3 Duration of pregnancy (n=66) Pregnancy M issing 26% Premature 1% Full term 73% Sixty-five patients (73%) were born at full term while 1 (1-%) patient was prematurely born. For 23 patients (26%) the duration of pregnancy was not recorded. 42

43 Family history of encephalocele Yes 2% Missing 18% No 80% Figure 4. Family history of encephaloceles (n = 73) In 71 (79.8%) patients there was no family history of encephaloceles. A positive family history of encephaloceles was found in 2 (2.2%) patients while in 16 (18.0%) patients this information was not available. The 2 patients with a positive family history were brothers. 43

44 Table 10. Special Investigations requested (n = 65) A) Ultrasonography, CT Scan and skull radiography results Results of investigations Investigations done Meningocele Meningoencephalocele Hydromeningoencephalocele Total No. of Patients (%) Ultrasound (15.7%) CT scan (42.7%) X-rays _ 13(14.6%) Ultrasonography was done on 14(15.7%) patients and 9 had features of meningocele. CT Scan was done on 38 (42.7%) patients and 22 of these had features suggestive of meningocele. Skull radiographs were done in 13 (14.6%) of the patients. (Table 10) 44

45 Table 11. Associated conditions at presentation Complication Frequency Percentage (%) CSF leak 8 9 Hydrocephalus Scalp wound sepsis Ulceration Neo-natal sepsis Anemia Discharging sinus Atrial septal defect Thirty patients (43%) had associated conditions at presentation. The commonest associated conditions at presentation were hydrocephalus 18 (20.2%), CSF leak 8 (9%) and anemia occurring in 4 (4.5%) patients (Table 11) 45

46 Table 12. Distribution of the lesion according to site Site of encephalocele Number of patients Percentage (%) Sincipital: Frontonasal Frontoethmoedal Frontoorbital Unspecified Posterior: Occipital Sub-Occipital Parietal Inter-Parietal Temporal Total As shown in table 12, majority of the patients (61%) had posterior encephaloceles. Anterior encephaloceles were found in the remaining 35 patients (39.3%). All anterior encephaloceles were sincipital, with fronto-nasal ones being the majority 25 (28.1%). Fronto ethmoidal were found in 8 (9%) and fronto-orbital in only 1 (1.1%) patient. In 1 patient the sincipital encephalocele was unspecified. (Table 12) 46

47 Table 13. Surgical Treatment Type of encephalocele Extracranial repair Surgical treatment Intracrania l repair VP shunt Total Anterior 23 (65.7%) 11(31.4%) 1(2.9%) 35(100%) Posterior 54 (100%) (100%) Figure 5 Surgical approach in repair of encephaloceles (n=88) e xc is io n - extra c ra n ia l (an te rior le s ion s ) 2 6 % V P s h u n t on ly 1 % In tra c ra n ia l 1 2 % extra c ra n ia l exc is ion (p o s terior les io n s ) 6 1 % As expected all patients with posterior lesions 54 (60.7%) underwent extracranial excision of their encephaloceles. Twenty-three (25.8%) of those with anterior lesions underwent extracranial excision while 11 (12.4%) had intracranial repair of their encephaloceles. Only 1 (1.1%) patient who had an anterior encephalocele, had a VP shunt inserted with no repair of encephalocele done. (Figure 5 and Table 12) 47

48 Figure 6 Excision of neural tissue Thirty (33.7%) patients had excision of neural tissue at repair of encephaloceles while majority, 59 (66.3%) patients did not. (Figure 6) Excision of neural tissue Yes 34% No 66% 48

49 Table 14. Surgery for insertion of VP Shunts (n=30) Type of encephalocele VP Shunt inserted Yes No Total Posterior 18 (33.3%) 36 (66.7%) 54 Anterior 12(34.4%) 23 (68.6%) 35 The frequency in the number of patients with posterior encephaloceles who underwent VP shunt surgery after repair of encephaloceles was nearly the same as that observed in patients with anterior encephaloceles who underwent the same procedure i.e. 33.5% and 31.4% respectively, this difference was not statistically significant. 49

50 Table 15. Table showing time intervals between repair and VP Shunt surgery (n=29) Time interval between main operation and shunt surgery (months) Pre-operative shunt surgery (%) Intra-operative shunt surgery (%) < 1 6(20.7) - 7 (24.1) (6.9) - 4 (13.8) > 6 4 (13.8) - - TOTAL 12 (41.4) 6 (20.7) 11 (37.9) Post-operative shunt surgery (%) In 6 patients (20.7%) VP shunts were inserted up to 1 month before repair of encephalocele while 7 patients (24.1%) had them inserted within 1 month postoperatively. Only 6 (20.75) patients had insertion of VP shunts at the same time as repair of encephalocele. (Table 15) 50

51 Post operative hospital stay The longest period of stay in the ward after undergoing operation was between 8 to 14 days, 32 (36%) patients. Next were those discharged within one week, 28 (31.5%) patients. The longest stay after surgery was 80 days and the shortest, 1day. Most of the patients (68%) were discharged from hospital within two weeks of undergoing surgery (Table 16) Table 16. Post op hospital stay in days Number of Number of Percentage days patients > Total

52 Table 17. Duration of hospital admission Number of days in hospital No. of patients > Total Percentage The average duration of hospital stay was 46 days. Thirty percent of the patients were discharged within 20 days of admission into the hospital. Fifty percent between 20 and 70 days and 10 percent after more than three months (Table 17). 52

53 Table 18. Follow up after surgery Post-op follow up period Number of patients Percentage 0-1 month > 1-6 months > 6-12 months > 12 months Total Thirty-six patients (40.4%) were lost to follow-up within one month of discharge from the hospital. Only 3 patients (3.4%) were followed up for more than 5 years. The longest follow-up period was 10 years. (Table 18) 53

54 Table 19. Number of patients with complications following surgery in different age groups. Age Category (months) No. of patients with complications Yes No Total no. of patients (61.4%) 17 (38.6%) 44 > (42.3%) 15 (57.7%) 26 > (50%) 6 (50%) 12 > 12 5 (71.4%) 2 (28.6%) 7 Total 49 (55.1%) 40 (44.9%) 89 The lowest complication rate was in the age category 1 6 months (42.3%). The highest complication rate was in those older than 1 year (71.4%, 5 patients) followed by those younger than1 month (61.4%,27 patients). The chi square test was not valid so there was no association between age and complications following surgery. 54

55 Complications of surgery Fifty-nine patients (55.1%) developed complications of surgery. The common wound complications were sepsis, dehiscence, necrosis and ulceration with delayed healing. Wound complications were the commonest (19.1%) followed by hemorrhage (18%). Other complications were CSF leak, cranial facial disruption and others as shown on the table below. (Table 20). Table 20. Complications of surgery Complication Frequency (%) None 40 (44.9%) Wound complication 17 (19.1%) CSF leakage 5 (5.6%) Haemorrhage 16 (18%) Hydrocephalus 3 (3.4%) Cranial facial disruption 4 (4.4%) VP shunt 5 (5.6%) blockage/infection Seizures 2 (2.2%) Osteomyelitis of 2 (2.2%) osteoplastic flap Ventriculitis 2 (2.2%) Meningitis and local 2 (2.2%) abscess 55

56 Table 21. Recurrence of anterior encephaloceles following surgery Surgical Approach No Recurrence Yes Total Extracranial 17(73.9%) 6(26.1%) 23(67.6%) Intracranial 9(81.8%) 2(18.2%) 11(32.4%) Total 26(76.5%) 8(23.5%) 34(100%) Recurrence rate was 26.1% for extracranially repaired anterior encephaloceles and 18.2% for intracranial repair. This difference was found not to be statistically significant. (Fishers' exact Test p = 0.48). (Table 21). Table 22. Recurrence of all encephaloceles following surgery Type of encephaloceles Yes Recurrence No Total Anterior 8 (22.8%) 27 (77.1%) 35 (39.3%) Posterior 3 (5.6%) 51 (94.4%) 54 (60.7%) Total 11 (12.4%) 78 (87.6%) 89 (100%) For posterior lesions recurrence was 1% (3 patients) compared to 22.9% (8 patients) for all anterior lesions. This was statistically significant (Fisher's exact test: p = 0.02). (Table 22). This may be a reflection of the technical difficulties encountered in the repair of anterior encephaloceles. 56

57 Causes of Death Table 23. Analysis of the 8 patients who died Year of death Location of encephalocele Cause of death Pre-operative complication Time of death after surgery 12 days 1992 Occipital Hydrocephalus septicaemia None 1996 Occipital Unkown None 4 months 1996 Occipital VP shunt Hydrocephalus 3 weeks infection malnutrition 1997 Fronto nasal CSF drainage None 15 days 1999 Fronto nasal Ventriculitis Hydrocephalus 46 days blocked shunt 1999 Occipital Hydrocephalus None 5 months Malnutrition 1999 Occipital Blocked VP Hydrocephalus 3 months shunt 2000 Occipital meningitis Meningitis 7 days Mortality among the study cases was 9% (8 patients) with 50% (4) of these patients having complications at presentation. Seventy-five percent of those who died had posterior encephaloceles with only 25% having had anterior lesions. Both of those with anterior lesions, who died, had frontonasal encephaloceles. 57

58 DISCUSSION Encephaloceles are common congenital malformations causing disfigurements, facial or cranial, that are usually clearly visible at birth. In this study 78.6% of the children presented within 6 months of birth majority of who were neonates (50%). Most of the patients (79.8%) were referred from other health providing institutions with majority of these coming from district hospitals (38.2%). This clearly indicates that patients with encephaloceles were referred early to Kenyatta National Hospital from the peripheral health institutions. For those who presented late (older than 6 months) it was not possible to determine at what age the child was first seen at the health institutions due to lack of and/or unavailability of clear and detailed referral notes. In the study there were more females than males, with a ratio of 1.9:1. A higher proportion of males (45%) had anterior encephaloceles compared to females (35%), while 69% of those with posterior encephaloceles were females. This pattern resembles that seen in Nigeria and over most parts of the world that shows a female predominance in children with encephaloceles (17,42). Anterior encephaloceles usually show no sex preference while 70% of all posteriorly located encephaloceles occur in females. (1) 58

59 In this study 61% of the encephaloceles were posterior with anterior lesions accounting for the rest. Adetiloye et al (43) in his ten year retrospective study in a teaching hospital in Nigeria found the distribution of encephaloceles was occipital (75%), occipital parietal (16.7%) and frontonasal 8.3%. The incidence of anterior encephaloceles varies with geographical location with Southeast Asian countries (44) having the highest. Thailand has the highest incidence (1:5000 live births) of anterior encephaloceles while in South Africa, occipital and frontal lesions enjoy equal distribution (3). Parietal, inter parietal, suboccipital and temporal encephaloceles were also encountered in this study but in low frequency. All anterior lesions were sincipital with frontonasal being the commonest, occurring in 25(28%) patients. Naso orbital occurred in 1(1.1%) while nasoethmoidal occurred in 8 patients (9%). No basal encephalocele was encountered. Among the oriental races nasoethmoid are the commonest sincipital encephaloceles (44,45). Yoshimoto et al (46) in his study in 1992 described basal encephaloceles as being very rare congenital anomalies constituting only 1 to 10% of all encephaloceles. It was noted in this study that most children were operated upon between the age of 1 month to 6 months (39.3%). With majority of those seen at presentation being neonates (49.7%), this peak age group at operation was attributed to the commonest time interval (1month to 6months) between presentation and surgery. The mean age at surgery was 12 months with the commonest age at operation being 3 months (17%). 59