UNUSUAL FEATURES OF LEPTOMENINGEAL CYSTS*

Transcription

1 VOL. 124, No. 2 UNUSUAL FEATURES OF LEPTOMENINGEAL CYSTS* By BEHROOZ AZAR-KIA, M.D., F.F.R., ENRIQUE PALACIOS, M.D., and RICHARD A. COOPER, M.D. MAYWOOD, 11HE purpose of this paper is to present 3 unusual cases of leptomeningeal cysts. Since first reported by Howship #{176} in i 8 I 6, leptomeningeal cysts have been the subject of many articles and experiments. Among the interesting features of leptomeningeal cysts presented in these papers have been the following: (a) their rarity in the occipital bone; and (b) the question ofwhether or not they freely communicate with cerebrospinal fluid circulation either via the yentricular system or the subarachnoid space. REPORT OF CASES ILLINOIS CASE I. K.H. is a 23 year old male who, at the age of 8 years, had aquaductal stenosis. He was treated by threading a rubber catheter from his third ventricle into the cisterna magna, thus creating a shunt. The surgery was performed through an occipital craniotomy. He did well for I I years following surgery and then began to suffer a gradual hearing loss. In the past few months h has had progressive ataxia, nausea, vomiting, and occipital headache. He is now practically deafand dependent upon lip reading. Physical examination reveals a deafness which the Otolaryngology Department feels is a neurosensory loss secondary to cochlear disease. The healed right occipital incision is not bulging. There is Grade I-Il papilledema bilaterally. The reflexes are hyperactive with sustained clonus at both ankles. Moderate truncal ataxia with mild extremity ataxia is present. The remainder of the examination is unremarkable. Laboratory: The laboratory findings were all normal. Skull roentgenograms (Fig. I) revealed a catheter extending from the third ventricle to the cisterna magna. Also present was an occipital lesion thought to represent a leptomeningeal cyst from the previous occipital craniectomy. A ventriculogram was performed which demonstrated the findings of obstructive hydrocephalus. The lateral and third ventricles were dilated. Air was seen to enter the fourth ventricle but did not pass into the cisterna magna. Following this, the patient was put in a sitting position and a lumbar puncture was performed with the introduction of approximately 40 cc. of air into the lumbar subarachnoid space. This air entered the leptomeningeal cyst (Fig. 2) but none appeared in the basal cisterns. The patient was then taken to the surgical suite where a right ventriculo-peritoneal shunt was performed. The patient recovered with a fixed dilated right pupil and diminishing papilledema. He is being followed in neurosurgery. CASE II. E.E. is a 53 year old male with a 12 month history of vaso-disorientation, decrease in recent and past memory, and extreme nervousness. Physical examination is unremarkable except for bilateral Grade I arteriosclerotic retinopathy and decreased vibratory sensation in the lower extremity. Laboratory: The laboratory findings are unremarkable. Roentgenography: A large bone defect is seen FIG. I. Case. Plain film roentgenogram. Shunt tubing extends from the third ventricle to the cisterna magna. Note a well-defined lobulated occipital bone defect representing a leptomeningeal cyst. * From the Department of Radiology, Stritch School of Medicine, Loyola University Medical Center, Maywood, Illinois. 287

2 288 B. Azar-Kia, E. Palacios and R. A. Cooper JUNE, 1975 FIG. 2. Case I. Later view in the Sitting position after introduction of air via a lumbar puncture demonstrates air-fluid level (-*) in the leptomeningeal cyst. Also note air from previous ventriculogram in dilated lateral ventricle. in the occipital region of the skull on plain film studies (Fig. 3). A pneumoencephalogram was performed (Fig. 4) with an injection of 10 cc. of air into the lumbar subarachnoid space. This revealed antenor displacement of the cisterna magna. There is no filling of the fourth ventricle, and the pontine cistern is compressed. It was felt that such changes were secondary to a large tumor, therefore left vertebral and right carotid angiographies were performed. The vertebral injection (Fig. A) revealed displacement of the cerebellar and posterior cerebral vessels anteriorly away from the inner table of the skull. There is extension of the tonsillar branches of the posterior inferior cerebellar artery below the foramen magnum as well as lateral displacement of the right posterior inferior cerebellar artery (Fig. SB). No tumor blush is identified. A right common carotid arterial injection reveals complete occlusion of the right internal carotid artery. It was concluded that an extracerebral and extracerebellar mass in the posterior fossa was causing these changes. It was felt that the mass was probably benign, and, with the associated defect in the occipital bone, was most lkely a leptomeningeal cyst. Surgery revealed a leptomeningeal cyst. Further questioning of the patient brought forth a history oftrauma to the occipital region many years before. CASE III. S.C. is a 13 year old male who, I year prior to admission, had dental x-rays taken which incidentally showed a lytic lesion in the left occipital region. History revealed that the patient fell at i8 months of age. The family physician found a cephalohematoma but no roentgenograms were taken. The patient was asymptomatic with a completely normal physical examination and laboratory studies. Skull roentgenograms again revealed a 3.5X6 cm. left occipital lytic lesion (Fig. 6). Occipital craniectomy revealed the presence of a leptomeningeal cyst. The cyst was excised and a portion of the pericranium was placed over the dural defect. The patient tolerated the procedure well and his postoperative course was unremarkable, DISCUSSION One of the unusual aspects of the cases presented is the rare location of these leptomeningeal cysts: occipital. Many authors state that the lesion is predominantly in the parietal bone, and Lende and Erick Case II. Leptomeningeal cyst creating an expansile bone defect in the occiput.

3 VoL. 124, No. 2 Unusual Features of Leptomeningeal Cysts 289 son 4 even state in a rare few cases it has been in the occipital bone. A review of the 69 cases reported by the various authors in the bibliography of this paper reveals : 38 (55 per cent) cysts occurred in the parietal bone; 8 (i 1.6 per cent) were parietal-frontal in location; 5 ( per cent) parietal-occipital; 2 (, per cent) parietal-temporal; i I (16 per cent) frontal; 4 (6 per cent) temporal; and only I (1.4 per cent) cyst was located in the occipital bone. The infrequency of occipital cysts becomes even more unusual in view of Glaser and Blame s6 observation that, at least in adults, fractures in the occipital area take much longer to disappear than in other parts of the cranium... in this group, some fractures of the occipital region were visible for an 8 year period. It is realized that Taveras and Ransohoff2#{176}and others state that it seems probable that the dural tear is the single most important factor in the pathogenesis of these lesions. However, since the relative frequency ofdural laceration with skull fractures in different cranial bones is not known, it does seem that delayed bone healing would encourage the formation of leptomeningeal cysts; yet occipital cysts remain very rare. An even more unusual aspect of this presentation is the communication between the leptomeningeal cyst and the subarachnoid space demonstrated in Case I. Whether leptomeningeal cysts communicate freely with the ventricular system or the subarachnoid space or do not communicate at all with the cerebrospinal fluid compartments has long been discussed. As early as i88i, Lucas 5 stated that... the cerebrospinal fluid tumor had communicated with the lateral ventricle. In 1884, Connor4 stated that... the sac is in direct communication with the subarachnoid and ventricular cavity. Cooperstock5 writes that definite increase in the tension of the mass could be made out when the patient cried, indicating the presence of its communication with the ventricular system. However, no pneumoencephalogram was -- FIG. 4. Case II. Tomogram after injection of air via a lumbar puncture reveals anterior displacement of the cisterna magna (-*). performed and subsequent surgery did not reveal a definite communication. Taveras and Ransohoff2#{176} state that the fluid contaming pockets are not true cysts because they are not completely isolated from the subarachnoid space, although they are confined by pia-arachnoid adhesions from free communication with the remainder of the subarachnoid space. Schwartz, 9 even before Taveras and his co-worker, had suggested that the cysts were isolated by innumerable subarachnoid trabeculae. Arseni and Simionescu2 state that there is free communication between the subarachnoid and subcutaneous spaces maintained by the torn dura and the diastasis of the bone, but they have performed pneumoencephalograms on patients with leptomeningeal cysts and have failed to demonstrate the communication they propose. Pneumoencephalograms have also been reported by Lende and Erickson 4 and Taveras and Ransohoff#{176} in which no communication with the leptomeningeal cysts is demonstrated. Matson 7 writes that if air is injected through the scalp into the cyst, it usually outlines the limits of the extracerebral lesion, but does not enter the

4 290 B. Azar-Kia, E. Palacios and R. A. Cooper JUNE, 1975 I I FIG.. Case II. Vertebral injection in the (A) lateral view shows downward displacement of the tonsillar branches of the posterior inferior cerebellar artery (PICA) (-t--) as well as anterior displacement of the vermian and hemispheric branches (-9), indicating an extracerebellar mass. (B) I he anteroposterior view demonstrates lateral displacement of the right PICA (-p). ventricles or intracranial su barachnoid space. On the other hand, if pneumoencephalographv is carried out in such patients, small amounts of air ordinarily - Fic. 6. Case III. Plain film roentgenogram shows the well-defined, expansile, large bone defect of an occipital leptomeningeal cyst. / enter the extracranial cystic structures. However, he does not present any roentgenograms to support this. In 1970, Rosenthal et al. 8 created leptomeningeal cysts in puppies. They then injected 10 cc. of India ink into the subarachnoid space via a cisternal puncture. They then opened the cyst to search for the India ink and found none. They write in all cases the India ink remained in the subarachnoid space and did not enter or stain the cyst fluid. We do not claim our single case to refute the elegant experiment of Rosenthal et al., 8 but we do present it as an example of communication between the subarachnoid space and the leptomeningeal cyst. We conclude that some cysts may communicate with the subarachnoid space while others are walled off by adhesions. Also of interest is the intracranial mass effect created by the cyst in Case II. Both Cooperstock and Taveras and Ransohoff2#{176} report intracranial extension of leptomeningeal c\?sts. In both cases, however, the extension of the cyst was only 2 cm. F-.4 4

5 VOL. i, No. 2 Unusual Features of Leptomeningeal Cysts 29! Lende and Erickson 4 report a larger intracranial cyst beneath a growing skull fracture of childhood but state that it had the appearance of a porencephalic cyst. Case ix does demonstrate a leptomeningeal cyst mimicking a large intracranial tumor. SUMMARY Three leptomeningeal cysts are demonstrated in their most unusual location, in the occiput. In addition, one cyst is shown to have free communication with the subarachnoid space and another displays an intracranial mass effect. Behrooz Azar-Kia, M.D. Department of Radiology Loyola University Medical Center 2160 South First Avenue Maywood, Illinois REFERENCES i. ARENDT, J. Bone rarefaction after skull injuries. Radiology, I945, 45, ARSENI, C., and SIMIONESCU, M. D. Growing skull fractures of childhood: particular form of posttraumatic encephalopathy. Acta neurochir., 1966, 15, CHILDE, A. E. Localized thinning and enlargement of cranium with special reference to middle fossa. AM. J. ROENTGENOL., RAD. THERAPY & NUCLEAR MED., 1953, 70, CONNOR, P. S. Traumatic cephalhydrocele: with report of two cases. Am. 7. M. Sc., 1884, 88, 103-I 10.. COOPERSTOCK, M. Leptomeningeal cyst associated with hemiplegia and skull defect of traumatic origin. 7. Pediat., 1946, 28, GLASER, M. A., and BLAINE, E. S. Fate of cranial defects secondary to fracture and surgery. Radiology, 1940,34, GOLDSTEIN, F., SAKODA, T., KEPES, J. J., DAVIDSON, K., and BRACKETT, C. E. Enlarging skull fractures: experimental study. 7. Neurosurg., 1967, 27, GRUBER, F. H. Post-traumatic leptomeningeal cysts. AM. J. ROENTGENOL., RAD. THERAPY & NUCLEAR MED., I969, 105, HAwARD, J. W. On case of fracture of skull, followed by pulsating fluid tumor of scalp and escape of cerebrospinal fluid. Lancet, 1869, 2, H0w5HIP, J. Practical Observations in Surgery and Morbid Anatomy. Longman, Hurst, Rees, Orme and Brown, London, 1816, 8, pp Q uoted in Lende and Erickson. 4 I I. JUPE, M. H. Reaction of bones of skull to intracranial lesions. Brit. 7. Radiol., I938, ii, I KEENER, E. B. Experimental study of reactions of dura mater to wounding and loss of substance. 7. Neurosurg., 1959, z6, LENDE, R., and ERICKSON, T. C. Cranial defects developing at fracture sites in children. Tr. Am. Neurol. A., I959, 28, 130-I LENDE, R. A., and ERICKSON, T. C. Growing skull fractures of childhood. 7. Neurosurg., 1961, z8, Low, N. L., and CORRELL, J. W. Head pain ue to leptomeningeal cysts. Brit. 7. Surg., 1966, 53, LUCAS, R. C. Second case of fracture of skull, followed by collect on of cerebrospinal fluid beneath scalp. Guy s Hosp. Rev., 1881, 25, 9I MATSON, D. D. Neurosurgery in Infancy and Childhood. Second edition. Charles C Thomas, Publisher, Springfidd, Ill., 1969, pp. 159, i8. ROSENTHAL, S. A. E., GRIESHOP, J., FREEMAN, L. M., and GOLDSTEIN, F. P. Experimental observations on enlarging skull fractures. 7. Neurosurg., I970, 32, SCHWARTZ, C. W. Leptomeningeal cysts from roentgenological viewpoint. AM. J. ROENT- GENOL. & RAD. THERAPY, I94I, 46, TAvERAS, J. M., and RANSOHOFF, J. Leptomeningeal cysts of brain following trauma with erosion of skull. 7. Neurosurg., 1953, 10, !. 2I. YARZAGARAY, L. Craniocerebral trauma in children. Surg. Clin. North America, 1973, 53, 59-7!.

6 This article has been cited by: 1. T.S. Sato, T. Moritani, P. Hitchon Occipital Intradiploic CSF Pseudocyst: An Unusual Complication of a Ventriculoperitoneal Shunt Malfunction. American Journal of Neuroradiology 30:3, [CrossRef]