J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.46.12.1102 on 1 December 1983. Downloaded from

Journal of Neurology, , and Psychiatry 1983;46:1102-1107 Arachnoid in the middle cranial fossa: cause and treatment of progressive and non-progressive symptoms FGA VAN DER MECHE,* R BRAAKMANt From the Departments ofNeurology* and Neurosurgeryt, University Hospital Rotterdam-Dijkzigt, Rotterdam, the Netherlands SUMMARY Ten consecutive patients with arachnoid cysts in the middle cranial fossa, diagnosed by CT, were studied. They were divided into three clinical groups: (1) four patients with progressive symptoms caused by secondary , (2) five patients with non-progressive symptoms of or , and (3) one asymptomatic patient. The nine symptomatic patients were operated upon and eight showed clinical improvement. Measurements of the CT scans revealed equal brain volumes on the affected and normal sides, refuting the hypothesis that the is caused by agenesis ofthe . The hemicranium on the affected side was larger, accommodating both the cyst and a normal brain volume. The progressive symptoms after bleeding were caused by brain shift and increased CSF pressure. The cause of the non-progressive symptoms has not yet

been established: two mechanisms are suggested: (1) expansion of the cyst accompanied by Protected by copyright. compression of surrounding structures, and (2) disturbed CSF dynamics without increased intracystic pressure. Removal of the membranes of the cyst with an opening to the basal cisterns should resolve both problems. After a residual cyst may remain.

Arachnoid cysts in the middle cranial fossa are be caused by (1) a space-occupying effect with usually considered to be developmental in nature. pressure on surrounding structures, (2) a change in They seem to occur predominantly in children and CSF dynamics, (3) agenesis or dysgenesis of the adolescents, especially males, and more often on the temporal lobe, especially in the case of epilepsy. left than on the right side.' Temporal lobe agenesis If the cause is identified, then the appropriate syndrome is another name given to this condition, therapy can be applied: that is decompression by cyst because during surgery it was discovered that the drainage to the peritoneal cavity or right cardiac temporal lobe was absent or only partly developed.' atrium, or regulation of CSF flow by membranec- In the past, patients presented with either asymp- tomy and opening of the suprachiasmatic cisterns, or tomatic bulging of the head or with progressive no surgical treatment at all if epilepsy is caused by symptoms, suggestive of a space-occupying lesion, dysgenesis of the temporal lobe. usually caused by a secondary subdural bleeding. In a first attempt to solve this problem we studied Many cases, however, remained undetected as retrospectively ten consecutive patients diagnosed by http://jnnp.bmj.com/ revealed by an unsuspected incidence of 5 per 1000 in CT. They were divided into groups according to their a systematic necropsy study.2 As a result of increasing symptoms: (1) progressive symptoms defined as availability of CT, arachnoid cysts are now more headache combined with nausea, vomiting, diplopia frequently diagnosed in relation to headache and or papilloedema suggestive of raised intracranial epilepsy. If the association with these non-progres- pressure, and (2) non-progressive symptoms: head- sive conditions is not coincidental, symptoms might ache or epilepsy.

Patients and methods on September 23, 2021 by guest. Address for reprint requests: FGA van der Meche, University Between June 1977 and August 1981, an arachnoid cyst in Hospital Rotterdam-Dijkzigt, 40 dr. Molewaterplein, 3015 GD the middle cranial fossa was diagnosed in 10 patients by CT. Rotterdam, the Netherlands. Nine patients were surgically treated; one patient was Received 10 April 1983 asymptomatic. Six patients were male; in seven cases the Accepted 2 June 1983 cyst was located on the left side; the median age was 12-5 1102 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.46.12.1102 on 1 December 1983. Downloaded from

Arachnoid cysts in the middle cranialfossa: cause and treatment 1103 Table 1 Clinical data CTscan data Follow-up Pt no. Sex Age Srmptoms (duration) Cyst size Bleedinig Midlinie Duirationi (yr) (cm-?) shift (moniths) Reslults Patients with non-progressive symptoms 1 m 30 headache (6 months) 3 - - 6 free of symptoms epilepsy (1 wk) (no medication) 2 f 9 epilepsy (6 months) (numerous 10 - _ 9 verv much improved generalised convulsions) onlv 1 focal fit with medication. as before 3 m 37 headache (>4 yrs) 22 - - 21 unchanged 4 m 9 headache (6 vrs) 31 - - 54 free of headache epilepsy (1 month) fits from a focus contralateral to the cyst 5 m 4 headache during walking (months) 29 - + 16 free of symptoms development accelerated'? Patients with progressive symptoms 6 m 16 headache nausea 63 subdural + 16 free of svmptoms vomiting, apathy (2 wks) haematoma 7 m 7 headache, diplopia 28 subdural + 24 free of symptoms apathy. papilloedema (3 months) haematoma 8 f 10 headache. nausea 182 subdural + 18 free of svmptoms vomiting, apathy (1 mnth) haematoma 9 f 15 headache, nausea 118 intracvstic + 6 free of symptoms vomiting. papilloedema (1 mnth) hacmatoma Patient without symptoms 10 f 24 - 46 - years (range 4 to 37 years). These figures are in accordance (see results). The second, indirect method assumes an with those in the literature.3 4 Table 1 presents further increase in skull diameter on the affected side compared Protected by copyright. details. with the normal side, if it has to contain both the cyst and the The operation consisted of removal of the outer mem- normal volume of brain tissue. Therefore, the skull brane of the cyst and opening the inner membrane to create "radius" was measured on both sides at the level of the a connection with the suprachiasmatic cisterns. Histology- pineal gland perpendicular to the midline. not performed in patients 2 and 5-showed arachnoid membranes in all others. At the end of 1981 all patients were Results seen by the first author. They were interviewed following a standard protocol and examined in detail for any minor Nine patients were symptomatic. Four patients focal deficit presented withprogressive symptoms related to raised CT scan measurements CSFpressure or brain shift (patients 6, 7, 8, 9). They In order to confirm or disprove the hypothesis of agenesis of developed headache combined with nausea, vomit- brain tissue, the volumes of the left and right hemispheres ing, double vision or general malaise, all after minor were compared. To avoid measuring temporary volume trauma. All had a secondary bleeding: in three this changes, for example, those caused by secondary bleeding, was due to a subdural haematoma, and in one an a postoperative CT scan obtained at the time of follow-up intracystic bleeding. In retrospect, three of the four was used. Two procedures were followed: (1) direct volume patients had at an earlier stage complained of non- measurement, and (2) measurement of the skull "radius" as progressive symptoms: headache, general malaise an indirect method. For direct volume measurements, only and deteriorating academic performance. After sur-

the scans with three or more slices above the lateral http://jnnp.bmj.com/ ventricles were used, in order to include as much brain gery all patients were free from symptoms. tissue as possible. The scan of patient 1, with the smallest Five patients presented with non-progressive cyst, was accordingly excluded. Tissue of the brain-stem and symptoms. Four of them had complained of head- the cerebellum was excluded if it could be clearly distin- ache for months (patients 1, 5) or even years (patients guished on both sides. All scans were analysed by re- 3, 4). In patient no 4 only, was this related to minor drawing on paper the cyst and brain tissue from both sides. trauma six years previously. In three of them, the Subsequently the pieces of paper were cut out, weighed and pain was not localised; in the fourth (patient 3) the their weights compared with the weight of a standard pain was usually on the side of the cyst, but surface area. The weight of re-drawn and cut standard occasionally contralateral. He was the only patient on September 23, 2021 by guest. surface areas of 100 cm2 showed a variation of < 1% (n = 5). Knowing the thickness of the CT slice the volume could be who did not benefit from the operation. None of calculated from these surface areas. The scan of patient 8 these patients showed signs of haemorrhage at could be measured with an off-line computer-assisted CT operation nor on histological examination of the scan analyser (Philips). The manual analysis of this patient membrane. Three patients suffered from epilepsy differed by only 3% from the computer-assisted analysis (patients 1, 2, 4; for patient 2 it was the only J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.46.12.1102 on 1 December 1983. Downloaded from

1104 van der Meche/, Braakman

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Figl1CTscan ofpatient 8: (a) preoperatively aleft-sided cyst is present with acomplicating subdural is, haematoma; (b) postoperatively no haematoma is visible; note that the cyst has re-expanded; the patient however free of symptoms. symptom). In two patients the side of the cyst was loss of brain tissue. The volume measurements made consistent with focal characteristics of either the by hand are summarised in table 2; the cyst volumes convulsion or the EEG. In the third patient (no 4) the and the brain volumes on the affected side were focal epileptic signs were consistent with the EEG related to the normal side. Irrespective of the size of focus, but inconsistent with the side of the cyst; this the cyst, the brain volumes on both sides were Protected by copyright. was the only patient whose epilepsy did not improve approximately equal, the mean value on the affected as a result of operation; his chronic headache, side being 101-4 ± 3 8%. This is not significantly however, disappeared. different from the normal side (Student's t test for paired observations). CT SCAN MEASUREMENTS The results of the indirect method, measuring the The case of patient no 8 makes it clear that the cyst skull "radius" on both sides at the level of the pineal was formed by a space-occupying lesion rather than gland, are presented in fig 2. The difference between agenesis of the temporal lobe. The large cyst became the affected and the normal side is proportionally symptomatic because of a complicating subdural larger in skulls with larger cysts. haematoma following minor trauma (fig la): 18 months after the operation a large cyst was still present (fig lb). It is evident, however, that the loss of brain space had been compensated for. The computer-aided volume measurements were as fol- 15 lows: cyst: 182 ml; both left and right supra- 0 E tentorial brain volume: 530 ml. Hence, there was no u http://jnnp.bmj.com/

Table 2 Cyst and brain volume ofthe affected side .2.V 10- expressed as thepercentage ofthe brain volume on the .2 0 normal side 4, 0 0 Pt. No. Brain volume Cyst volume (%) 0 side C affected (%) 4, 0*5 1 not measured < 1 2 ._ * *: 2 97 0 3 106 3 on September 23, 2021 by guest. 4 106 5 5 102 6 6 105 12 O 50 160 150 200 7 103 5 Cyst volume (cm3) 8 97 32 9 98 21 Fig 2 Relationship between volume ofcyst and difference 10 99 10 in 'radius' between the affected and the normal side. J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.46.12.1102 on 1 December 1983. Downloaded from

Arachnoid cysts in the middle cranialfossa: cause and treatment 1105 DEXTERITY AND PSYCHOLOGICAL 9). The surgical therapy consists of releasing the FUNCTIONING haematoma and removing the cyst. The results were Considering temporal lobe agenesis as a possibility, excellent and comparable to those in the literature we looked for signs of functional impairment. The listed in table 3; only the series that specified their intellectual function in all patients but patient no 5 results according to complaints have been included was average or even above average with regard to here. educational or occupational level. For instance, the Non-progressive symptoms such as headache or girl with the largest cyst (fig 1) had excellent school epilepsy can occur with cysts uncomplicated by results and was socially fully integrated. Patient no 5 bleeding. Sometimes this is attributed to expansion differs from the others in that he was born with a skull of the cyst; a valve mechanism" or active secretion19 circumference in excess of the 98th percentile; this has been suggested. An indirect argument for indicates growth of the cyst before birth. He expansion could be a large rounded cyst showing presented with headache during walking, but other signs of compression on the CT scan.22 Patients 4 and complaints were delayed development of speech and 5 fulfil this radiological criterion. If expansion occurs enuresis. After the operation a considerable cyst still before birth, it should result in skull enlargement, existed (29 ml). Despite this, his development possibly with some brain damage (patient 5). Aicardi following operation had, according to his parents, and Bauman,' however, reported macrocrania of a accelerated to near-normal level. severe degree without any neurological signs or Seven of the cysts were located on the left side. abnormalities in development, in accordance with Five of these patients, including those with the largest the conclusion that there is no loss of tissue. cysts, were nevertheless right-handed. More often non-progressive symptoms are found in patients with angular cysts without signs of Discussion expansion (patients 1-3). The cause of this has not yet been clarified. It has, however, been known for

Developmental cysts in the middle cranial fossa are some time that many cysts are in fact diverticula. Protected by copyright. sometimes considered to be primary arachnoid Surgery has revealed an opening to the basal malformations,'122 but more often they are believed cisterns4 2 23 and on cisternography the cyst can be I I` to be secondary fluid collections' 23 in the shown to fill with air,26 isotope'3 27 or absence of a part of the temporal lobe. Absence of metrizamide.3 14 28 In these instances increased brain tissue should lead to a difference in brain intracystic pressure is unlikely to play a role. volume between the two sides. Volume measure- Nevertheless, operation has been reported to cause ments of the CT scans of these ten patients, however, relief of headache in three patients with led to the opposite conclusion: there was no loss of diverticula.'2-14 An explanation other than intracystic brain tissue, not even when the cysts were very large pressure could be a local change in the functions of (table 2). In addition, it could be demonstrated that the subarachnoidal space: (1) Disturbance of the the affected hemicranium was larger, the increase mechanical buffer for brain movement based on a being proportional to the size of the cyst, and smooth redistribution of CSF and fine trabeculation therefore able to harbour both the cyst and the within the subarachnoid space is certainly present normal brain volume (fig 2). Shaw24 demonstrated and could lead to abnormal traction and compres- the same phenomenon in a postmortem study of two sion. (2) Obliteration of the temporal subarachnoid brains with temporal cysts; he could not detect any

left/right difference in brain volume or weight. It can, http://jnnp.bmj.com/ therefore, be concluded that there was no loss of Table 3 Result ofoperation in patients with progressive brain tissue. Consequently the cyst has to be the symptoms caused by haemorrhage primary developmental disorder with secondary Authors No. of No. of Result displacement of the brain. This conclusion also patients explains why, in the great majority of cases, no motor Aicardi and 2 2 1 good deficit, not even a shift of handedness, and no Bauman, 19755 1 sudden death intellectual loss has been found in this series or in Smith and Smith, 19766 1 1 good others.3 4 Leo et al, 19797 1 0 improved on September 23, 2021 by guest. Progressive symptoms suggestive of increased CSF Heimans et al, 19798 2 0 good pressure or brain shift are caused by a decompensa- Galassi et al, tion of the intracranial contents, usually by subdural 19803 12 7 good or intracystic bleeding. This complication occurs Aueretal, 19819 5 5 good Varmaetal, 1981"' 6 6 good most frequently before the age of 20.4 Four such This series 4 4 good patients are included in this series (numbers 6, 7, 8, J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.46.12.1102 on 1 December 1983. Downloaded from

1106 van der Meche, Braakman Table 4 Result ofoperation in patients with the basis of non-progressive symptoms, but solely on non-progressive symptoms: headache the existence of a cyst, irrespective of the presenting complaint. Therefore, the high rate of postoperative Authors No. of Result Duration patients follow-up improvement suggested by the tables is probably Tiberin and valid. Further confirmation comes from our patients Gruszkiewicz, 196111 1 good 9 months 6, 7 and 9. They all had secondary haemorrhage after Torma and minor trauma. In retrospect, they also had chronic Heiskanen, 196212 2 good 1 and 7 years Seur and Kooman, 197613 1 good complaints. In all three, these disappeared after Smith and Smith, 19766 1 good 3 years some time. Non-progressive symptoms have there- Handa et al, 197714 1 good ? Anderson et al, 6 "good 8 months- fore a good prognosis after operation. 19791 results" 18 years Two different surgical approaches have been Leo et al, 19797 1 "improved" ? This series 4 3 good 6-54 months advocated: removing the outer membrane and 1 unchanged opening the inner membrane giving drainage to the basal cisterns3 6 8 10 12 15 3034 and cystocardial or space could also block the lateral CSF route to the cystoperitoneal drainage.26 35 36Since intracystic pres- site of absorption with intermittent rises in CSF sure is not necessarily related to the symptoms, pressure as has been found with solid tumours.29 Kato pressure regulation with drainage of the cyst does not et aP6 indeed found blockage of the lateral route in seem to be a logical first choice. Restoration of CSF two patients, and Stein27 even described an infant dynamics by removing the membranes should be with a diverticulum associated with communicating effective in all cases. Furthermore, the effectiveness . of different operations should not be judged by the The post-operative results of both groups, angular disappearance of the cyst on the CT scan. Because of cysts and round "expanding" cysts have been com- the early developmental displacement of the brain, bined. Three of four patients who suffered from one should expect a residual cyst after surgery. This is in la and b: after chronic headache were cured. The one patient who clearly demonstrated figures Protected by copyright. did not benefit from operation suffered from removal of the subdural haematoma the cyst even re- localised headache over the cyst, but sometimes expanded, while the patient became symptom-free. identical pain on the other side. Two years after the To summarise, the course of events may be as operation an open connection between the cyst and follows: During development, a cystic arachnoid the basal cisterns was demonstrated. In this case, it is malformation displaces the temporal lobe without possible that the were not related to the any functional loss. Symptoms, if any, are caused (1) cyst. by secondary haemorrhage, (2) by expansion of the Two of three patients with epilepsy benefited from cyst, or (3) by disturbed CSF dynamics without operation. The third had an epileptic focus on the increasing intracystic pressure. Surgery should aim to opposite side from the cyst. The epilepsy did not evacuate the mass and restore the CSF dynamics; improve but his chronic headache disappeared after postoperatively, a residual cyst can be expected. the operation. Previous studies have also shown that chronic headache and epilepsy can be improved or cured by We thank G Blaauw, J van Dongen and J van Gijn operation (tables 3 and 4). One may argue that only for their valuable comments, Mrs J Doornbosch for positive results are published. The original authors, secretarial help and Mrs BS Vollers-King for however, selected the patients in these tables not on language editing of the text. http://jnnp.bmj.com/

Table 5 Result ofoperation in patients with non-progressive symptoms: epilepsy Authors No. ofpatients Result Medication Duration follow-up Roger et al, 196416 1 good ? ? Vigouroux et al, 196617 2 good ? Bhandari, 197218 1 good -? Aicardi & Bauman, 19755 1 good ? 5 years Smith & Smith, 19766 1 good ? 5 years Heimans et al, 19798 1 improved + ? on September 23, 2021 by guest. Galassie et al, 19803 5 improved + 6 months-9 years Auer et al, 19819 3 good + 1-3 years This series 3 no change + 41 years improved + 9 months good - 6 months good = free from fits improved = significant reduction of fits J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.46.12.1102 on 1 December 1983. Downloaded from

Arachnoid cysts in the middle cranial fossa: cause and treatment 1107 References arachnoid cysts. J Neurol Neurosurg Psychiatry 1972;35:763-70. Robinson RG. The temporal lobe agenesis syndrome. Go KG, Houthoff HJ, Blaauw EH, Stokroos I, Blaauw Brain 1964;88:87-106. G. Morphology and origin of arachnoid cysts, scanning 2 Shaw CM, Alvord Jr. EC. "Congenital Arachnoid" Cysts and transmission electron microscopy of three cases. and their differential diagnosis. In: Vinken PJ and Acta Neuropathol 1978;44:57-62. Bruyn GW, eds. Handbook ofClinical Neurology, Vol. 20 Rengachary SS, Watanabe I. Ultrastructure and patho- 31, 1977;75-136. genesis of intracranial arachnoid cysts. J Neuropathol Galassi E, Piazza G, Gaist G, Frank F. Arachnoid cysts of Exp Neurol 1981;40:61-83. the middle cranial fossa: a clinical and radiological 21 Rengachary SS, Watanabe I, Brackett ChE. Pathogenesis study of 25 cases treated surgically. Surg Neurol of intracranial arachnoid cysts. Surg Neurol 1980;14:211-19. 1978;9:139-44. Robinson RG. Congenital cysts of the brain: arachnoid 2 Giudicelli G, Hassoun J, Choux M, Tonon C. malformations. Prog Neurol Surg 1971 ;4: 133-74. Supratentorial "Arachnoid" Cysts. J Neuroradiol 5Aicardi J, Bauman F. Supratentorial extracerebral cysts 1982;9: 179-201. in infants and children. J Neurol Neurosurg Psychiatry 23 Robinson RG. Intracranial collections of fluid with local 1975;38:57-68. bulging of the skull. J Neurosurg 1955;12:345-52. 6 Smith RA, Smit WA. Arachnoid cysts of the middle 24 Shaw CM. "Arachnoid cysts" of the Sylvian fissure versus cranial fossa. Surg Neurol 1976;5:246-52. "temporal lobe agenesis" syndrome. Ann Neurol Leo JS, Pinto RS, Hulvat GF, Epstein F, Kricheff JJ. 1979;5:483-5. Computed tomography of arachnoid cysts. Radiology 23 Al-Din AN, Williams B. A case of high-pressure 1979;130:675-80. intracerebral pouch. J Neurol Neurosurg Psychiatry 8 Heimans JJ, Duinen MThA van, Drift JHA van der. 1981 ;44:918-23. Arachnoid cysts in the middle cranial fossa. Clin 26 Kato M, Nakada Y, Ariga N, Kokubo Y, Makino H. Neurol Neurosurg 1979; 81:291-300. Prognosis of four cases of primary middle fossa Auer LM, Gallhofer B, Ladurner G, Sager WD, Heppner arachnoid cysts in children. Childs Brain 1980;7:195- F, Lechner H. Diagnosis and treatment of middle fossa 204.

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9: 169-87. 1979;28:619-26. on September 23, 2021 by guest. 18 Bhandari YS. Non-communicating supratentorial sub-