Surgery for Spinal Cord Lipomas

Transcription

1 39 Original Article Surgery for Spinal Cord Lipomas Manish K. Kasliwal and Ashok K. Mahapatra Department of Neurosurgery, Neurosciences Centre, All India Institute of Medical Sciences, New Delhi, India [Received June 5, 2006; Accepted October 11, 2006] ABSTRACT Objectives. To analyze the results after surgery for spinal cord lipomas. Methods. The authors report their results of management of 63 non consecutive random children with spinal cord lipomas treated over a period from 2001 to 2005, at the All India Institute of Medical Sciences, New Delhi, India, a tertiary care neurosurgical centre. Results. There were 63 cases consisting of 32 (52%) conus lipomas, 14 (22%) filum lipomas, 14 (22%) lipomeningomyelocele (lipommc), 2 (2.5%) cases of lipomyelocystocele and one (1.5%) case of mixed lipoma. None of the patients who were asymptomatic before surgery deteriorated neurologically, irrespective of the type of lipoma till the last follow up. In those patients with preexisting neurological deficits, the improvement in motor, sensory and bladder abnormalities was only to an extent of 15 %, 16 % and 21 % respectively. None of the children with preexisting neurological deficit regained overall normal function. Nevertheless, the improvement in symptoms after surgery made the patients lead a better social life. Only 6 % of patients developed deterioration in neurological function after surgery, all of them occurring in patients already having pre-operative deficits. Conclusions. The authors recommend prophylactic surgery which is safe and effective in preventing neurological deficits, irrespective of the type of lipoma. Most of the patients benefit only to some extent even after surgery, once they develop neurological dysfunction. A close long term follow up is recommended in order to detect neurological deterioration even in children operated prophylactically. [Indian J Pediatr 2007; 74 (4) : ] akmahapatra_22000@yahoo.com, m_kasliwal@yahoo.com Key words : Spinal lipoma; Lipomyelomeningocele; Tethered cord; surgery; Occult spinal dysraphism; Results; Conservative management. Spinal cord lipomas are lesions of childhood responsible for a significant number of cases of spinal cord tethering leading to progressive neurological deficits. 1,2 The natural history of these is poorly understood, and with the deterioration of results of prophylactic detethering over time especially in cases of conus lipoma, the performance of prophylactic surgery in children has recently been questioned. 2-5 This in fact has lead some neurosurgeons to conservative management of spinal cord lipomas in asymptomatic children. 4 However, the exact timing of neurological deterioration and its magnitude cannot be predicted. The outcome of cases operated after they have already suffered some form of neurological deterioration is not Correspondence and Reprint requests : Prof. Ashok K Mahapatra. (Professor and Head), Room No. 720, Department of Neurosurgery, Neurosciences Centre, All India Institute of Medical Sciences, Ansari Nagar, New Delhi , India. Fax: very good. 5,6 This fact can be emphasized to justify prophylactic surgery. The authors have analyzed their results of surgery for spinal cord lipomas over a five year period, the cases being neither total nor consecutive. Patients age and gender MATERIALS AND METHODS The case records of 63 patients who underwent surgical treatment for spinal cord lipomas were reviewed along with their follow up during a period from April 2001 to march The case were neither consecutive nor being the total number of lipomas operated over this period. Six patients had an earlier surgical intervention. Patients age, sex, symptoms and signs, radiological findings, any associated anomalies, surgical outcome and latest follow up were evaluated retrospectively and analyzed. All patients underwent surgical treatment with standard micro neurosurgical techniques even if neurologically 357

2 40 M.K. Kasliwal and A.K. Mahapatra intact once the diagnosis was made. Patients age at operation ranged from 15 days to 20 years (mean 4.89 years). There were 35 boys and 28 girls. Follow up of the patients ranged from 4 days to 1050 days (mean 130days). Symptoms and Signs The mean age of patients with any neurological or orthopedic symptoms was significantly higher (5.5 yrs) than those presenting without deficits (2 yrs). The children presented with symptoms such as skin abnormalities, orthopedic deformities, motor weakness, sensory involvement, scoliosis or bladder bowel involvement. Of the 63 children, 33 (52%) presented with some form of cutaneous abnormalities, the most common being subcutaneous lipoma in 23 (36.5%). The distribution of various cutaneous symptoms and signs were as shown [Diagram 1]. 13 patients (21 % ) presented with various orthopedic abnormalities consisting club foot ( 5), pes cavus (2), trophic ulcer (1), varus (3) or valgus (1) deformity and absent right forearm in one patient. Scoliosis was present in 18 patients (28.57 % ) and was the only abnormality in 3 patients. Neurological deficits were present in a significant number of children (Table 1). Fifteen (24 %) patients were totally asymptomatic, only the cutaneous manifestations were the presenting symptoms. Radiological findings and associated lesions : Magnetic Resonance imaging (MRI) (Fig. 1) was Fig 1A 1 4 Subcutaneous lipoma Sacral or 2 coccygeal dimple 3 Dermal sinus 23 Diagram 1. Cutaneous Markers Altered colored skin patch Tuft of hair No. of 12 patients Type of lipomas 4 0 LipoMMC Terminal Dorsal 1 Filum Transitional Filum and conus Lipomyelocystocele 2 Diagram 2 Fig 1B 358

3 41 Surgery for Spinal Cord Lipomas TABLE 1. Neurological Deficits Type of Neurological deficit No. of cases (%) Motor Sensory Motor and sensory Motor, sensory and autonomic Motor and autonomic Sensory and autonomic Autonomic 16 (25) 1 (1.5) 4 (6.5) 7 (11) 7 (11) 1 (1.5) 9 (14) TABLE 2. Imaging Findings Associated anomalies No. of patients (%) Fig 1C Fig 1D Fig. 1. Representative MR images of children showing subcutaneous lipoma (Fig 1a), lipomyelomeningocele (Fig 1b), conus lipoma (Fig 1c) with associated anomalies like syringomyelia (Fig 1a) and scoliosis and split cord malformation (Fig 1d). performed pre operatively in all children along with skeletal X-ray in some which revealed various associated abnormalities along with the spinal cord lipoma (Table 2). Cord was tethered in all the cases. Syringomyelia was noticed in 13 (21%) patients while Split cord malformations (SCM) were seen in 8 (13 % ) cases. Operative findings: All the patients underwent surgery with standard microneurosurgical techniques addressing the lipoma which was excised totally or partially to prevent post operative neurological deficit if required, along with addressing of all other possible Low lying cord 63 (100) Syrinx 13 (21) Split cord malformation 8 (13) Chiari malformation 5 (8) Hydrocephalus 7 (11) Vertebral anomalies 3 (5) Meningomyelocele 14 (22) Myelocystocele 2 (3) Neuroenteric cyst 1 (1.5) Sacral agenesis 1 (1.5) causes of tethering, if present. The various types of lipoma found intraoperatively were subclassified [Diagram 2]. Immediate post-operative complications Most of the patients had a smooth post-operative course. However, some patients did develop minor postoperative complications which resolved in two to three weeks time. Thirteen patients developed various complications consisting of post-operative transient urinary retention in 4, pseudomeningocele formation in 3, superficial wound infection in 3, CSF leak in 1 and wound dehiscence in 2 patients. Only the patients with CSF leak and wound dehiscence required resuturing, the rest of the complications being managed conservatively with antibiotics and proper nursing care. Reoperation Six patients in the present series who were operated previously at some other centre underwent reoperation due to retethering. These consisted of two cases of filum lipoma, three cases of lipommc and one case of conus lipoma. One of these was asymptomatic at initial presentation operated due to the identification of cutaneous abnormality and the rest five were symptomatic. The mean duration between the first and second operation was 60 months (range, 6 months to 89 months). RESULTS One patient died in the hospital after surgery probably 359

4 42 M.K. Kasliwal and A.K. Mahapatra as the result of apnea. Of the 34 patients who presented with some form of motor involvement, there was improvement in 5 (15 %) patients; deterioration in motor power in 2 (6 %) patients and in the rest, the motor symptoms remained stable. Both the patients belonging to the group having conus lipoma, developing deterioration in motor power developed it immediately following surgery the power remained the same with no improvement at one year follow up. Of the 15 patients with sensory involvement, improvement was seen in 2 (15%) patients with the remaining children showing no change after surgery. Autonomic symptoms responded the best to surgical intervention with 5 (21%) of the 24 patients showing improvement in bladder bowel symptoms after surgery. All the 18 patients with scoliosis had no progression of the kyphoscoliotic deformity after the surgery. There was no neurological deterioration in children who presented with only cutaneous swelling with no neurological signs and symptoms. Of all the cases, none of the patients with filum lipoma deteriorated after surgery with only two patients (6%) having neurological deterioration following surgery for conus lipoma. Three patients developed trophic non-healing foot ulcers on long term follow up. Among the children who underwent reoperations, of the two children who presented with urge incontinence, one had improvement in urinary problem and the other developed overflow incontinence and remained on clean intermittent self catheterization post-operatively. The children presenting with motor and sensory symptoms remained the same post operatively. There was no neurological deterioration in any of these patients. In most of the cases, syrinx resolved after the detethering and none of the cases required surgery for syrinx per se. The results following surgery are summarized in table 3. TABLE 3. Post Operative Results Type of Total Improved Deteriora- Same symptoms patients (%) tion (%) (%) Motor symptoms 34 5 (15%) 2 (6%) 27(79%) Sensory symptoms 15 2 (15%) - 13(85%) Autonomic symptoms 24 5 (21%) - 19(79%) DISCUSSION Spinal cord lipomas form a heterogeneous group of lesions accounting for a significant number of cases of spinal cord tethering in childhood. 1,2,5,7 Various forms of spinal cord lipomas can be lipomyelomeningocele, lipomyeloystocele, lipomas of the conus medullaris and of filum terminale However, the major subdivision into filum and conus lipoma has been used in most of 360 the studies in analysis of their outcomes following surgery on these lesions. 3,4,5,7 Congenital lumbosacral lipomas are a result of abnormal embryologic development, the primary abnormality being of brief disjunction in the separation of primitive ectoderm into neuroectoderm, neural crest and cutaneous ectoderm. 11 The pathophysiology of neurological deficits produced by the congenital lipomas is due to the effect of spinal cord tethering or compression produced by the presence of lipomas Tethering can be caused by a lipoma per se or elements such as thickened filum terminale, aberrant nerve roots and fibrous bands or dermal sinuses or of another conditions which may be associated with lipomas like SCM. 12,13 The importance of recognizing these cannot be overemphasized as failure to address this abnormal components during surgery can lead to non improvement or deterioration of the patient after surgery. The exact incidence of these lesions is not known with clinical estimate of 4 8/10,0000 reported in some studies. 2,5 There has been a significant difference between in the age at presentation between the symptomatic and asymptomatic group as has been duplicated in various studies earlier. 3,14,15 This feature indirectly points to the poor natural history of the disease as of gradual progression as the age of child increases, which though not understood fully due to various reasons, provides a ground for argument for neurosurgeons performing prophylactic surgery in children with lumbosacral lipomas. The clinical presentation of children with lumbosacral lipomas can be varied with the diagnosis being made either at birth or shortly thereafter due to the presence of some cutaneous abnormalities as described in literature up to an extent of more than 50 %, 2,5 a finding seen in about 52 % of patients in the present series, or later due to the presence of various neuro, orthopedic or urological abnormality. 2,4,5,7 The significance of cutaneous abnormality cannot be overemphasized as its recognition following with early MR imaging had revolutionized the management of children with the offering of prophylactic surgery in view of neurological deterioration if not intervened upon. Though a major group of neurosurgeons favors the same, this view had been challenged by a number of studies, recently. 3,5,16,17 The management issues in spinal cord lipomas have generated quite a controversy in the last few years, especially in asymptomatic cases. Before the anatomy of congenital lumbosacral lipomas became fully understood, surgery for this condition was considered risky and was not performed for asymptomatic children in view of avoiding post-operative neurological deterioration. This led to the delayed referral of patients

5 43 Surgery for Spinal Cord Lipomas for surgery, with more severe and irreversible neurological deficits, thus affecting the outcome of the surgery adversely. However, with the thorough understanding of the basic pathophysiology of the condition and with the appreciation of the fact that the natural history of this is inexorable with relentless progression of neurological deficits, if not treated as exemplified in various studies, more and more neurosurgeons started to perform prophylactic surgery. 15,18,19 However, this data is far from incomplete as it does not include a number of older asymptomatic cases who never come to medical attention further compounded by the fact that there are no randomized control trials studying the natural history of the disease. 3,5 A recent study analyzing the results of surgery with conservative management concluded no significant difference in the risk of neurological deterioration between the group managed conservatively as compared to the one treated surgically, thus arguing against the performance of prophylactic surgery. 3 Though the outcome following prophylactic surgery has been good in cases of filum lipomas, its role in conus lipoma has been variable, as reported in various studies questioning the role of prophylactic surgery. 2,4,20 In the analysis of results of 291 lipomas by Pierre Kahn, et al 2 the outcome following prophylactic surgery was excellent for filum lipomas which though good for conus lipomas in the short term, degraded over time with quite a significant number of patients showing neurological deterioration on long term follow up. Similarly Calenbergh et al 4 found no significant protection in patients after prophylactic surgery in asymptomatic patients. The outcome following prophylactic surgery for filum lipomas have been excellent in various series, 2,7,8,21 including the present one as well. Though most of the studies have reported excellent results following surgery for filum lipomas, Xenos, et al 5 however, reported a 40% incidence of neurological deterioration in their series. The effectiveness of surgery in preventing neurological deficits in this subgroup of lipomas has led to advocation of prophylactic surgery. The same has not been true in case with conus lipomas or lipommc. There has been quite a significant neurological deterioration on long term follow up even in asymptomatic patients as reported in various series providing argument against the performance of prophylactic surgery in these group of patients. 1,2,3,5,21 However, the incidence of neurological deterioration had been only 6 % in our series with all of it occurring in the immediate post-operative period inflicting the role of surgical insult in the pathogenesis of the same. A more conservative attitude in resection of conus lipoma can possibly prevent the same. Though none of the patients with pre operative symptoms in the present series recovered total function post-operatively, the improvement in motor and urinary symptoms led to improvement in the social functioning as reported in various studies in the literature as well. 2,5,16 The authors did not observe any late neurological deterioration in the present study after surgery for the conus lipoma, as reported in the literature, 1-5 which may be attributed to the shorter duration of follow up compared to other studies. There has been mixed results in various studies, however, addressing this issue due to which, the question of prophylactic surgery still remains controversial. 19,20 The 6 % incidence of early deterioration as has been consistent with the very small incidence of the same reported by Calenbergh et al 4 and Pierre Kahn et al 2 the incidence of which is expected to decrease over time with better refinement of the surgical techniques and better closure techniques. 1,2,5 CONCLUSIONS To conclude, spinal cord lipomas still represent a challenge with regard to the management issues. However, as per the results in the present study and as reported in the literature, surgery for filum lipomas is safe and effective and should be undertaken even when the child is asymptomatic; this provides the best chance of prevention of neurological deficits, as once the deficits appear the chances of reversal of the same are very less. As the authors have not found any significant deterioration in neurological status even in surgery for the conus lipomas, which may be attributed to the short follow up in the present study, it is believed that even this form of lipoma should be addressed surgically because these are bound to cause neurological deterioration in the future. However, this issue is a bit controversial with various studies reporting no benefit of prophylactic surgery as significant number of these patients deteriorate over time. A large randomized control study is required which may provide better insight into the management issues and will further clarify the role of prophylactic surgery especially in conus lipomas. REFERENCES 1. La Marca F, Grant JA, Tomita T, McLone DG. Spinal lipoma in children: Outcome of 270 procesures. Pediatr Neurosurg 1997; 26 : Pierre-Kahn A, Zerah M, Renier D, Cinalli G, Sainte-Rose C, Lellouch-Yubiana A et al. Congenital lumbosacral lipomas. 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