rournal ofNeurology, , and Psychiatry 1995;59:293-298 293 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.59.3.293 on 1 September 1995. Downloaded from Arachnoid of the left temporal fossa: impaired preoperative cognition and postoperative improvement

Knut Wester, Kenneth Hugdahl

Abstract possible toxic products. The mechanisms Thirteen adult patients were operated on underlying neurological deficit in such indo- for symptomatic arachnoid cysts in the lent lesions as arachnoid cysts are far from left temporal fossa; seven with an inter- clear. The is seldom nal shunt procedure during local anaes- raised enough for reduced tissue perfusion to thesia, and five with a with be the mechanism underlying loss of function. fenestration of the to the basal cis- Because clinical improvement may occur after terns. In one patient, an initial internal decompression, it would seem likely that the shunt was transformed to a cystoperi- neurological deficit is related to processes toneal shunt. After , all patients which, although impairing neuronal function, experienced relief of symptoms. do not necessarily result in cell death. Reduction of cyst volume occurred in 11 Arachnoid cysts are thought to be due to a patients. The patients were tested for maldevelopment of the cerebral ."2 brain asymmetries related to language This may be present at birth or develop soon and verbal memory before and after after.34 After an initial growth in early life, operation, with a dichotic listening tech- most cysts are thought to remain stable over nique with simultaneous presentation of many years,5 having reached a permanent size different auditory stimuli to the two ears. which may well be substantial. Very few cysts In the preoperative memory test, the have been reported to disappear sponta- patients showed impaired total recall neously.6-'0 Moreover, some seem to continue compared with healthy control subjects, to grow in adult life; although slowly." and recall from the right ear was signifi- The symptoms associated with arachnoid cantly impaired. The patients also per- cysts vary according to the site of the lesion formed poorly in a forced attention task and the neural structures surrounding them. consisting of dichotic presentations of In adults, subjective complaints such as consonant-vowel syllables. In addition to and dizziness are common. Major clinical improvement, the surgical proce- neurological symptoms such as motor or sen- dures led to improvements in both sory deficits, , or language problems dichotic perception and memory. Overall may also occur, although they are often slight memory performance was enhanced, and tend to develop late in life. The lack of

mainly because of improved recall from dramatic symptoms, even in patients with http://jnnp.bmj.com/ the right ear. This normalisation of large arachnoid cysts, probably reflects the memory function was found as early as brain's ability to compensate for the presence four hours after the operation. The of a slowly growing or stable expansion. results indicate that arachnoid cysts in If arachnoid cysts cause disabling symp- the left temporal fossa may impair cogni- toms such as a paresis, dysphasia, epilepsy, or tive function, that neuropsychological severe headache, or they are complicated by a tests are necessary to disclose these subdural haematoma, there is a clear indica- impairments, and that cognitive tion for surgery. On the other hand, if the on September 27, 2021 by guest. Protected copyright. Department of improvement occurs after surgery. symptoms are less dramatic, some authors Neurosurgery, favour conservative treatment.'2-'7 The rela- University of Bergen, (3 Neurol Neurosurg Psychiatry 1995;59:293-298) tive paucity of symptoms despite massive dis- School ofMedicine, Haukeland Hospital, placement of brain tissue is taken to indicate N-5021, Bergen, satisfactory cerebral compensation.'8 Norway Key words: arachnoid cysts; language; memory. Moreover, some earlier series reported a sig- Knut Wester nificant mortality and morbidity after surgery Department of for these Biological and "uncomplicated" cases, and this has Medical Psychology, Lesions occupying intracranial space, such as also prompted caution.'3 19-22 University of Bergen, haematomas, tumours, or cysts may impair In common with any other intracranial Arstadveien 21, N- brain function. The underlying mechanisms expansive lesion, arachnoid cysts have the 5011,Bergen, Norway Kenneth Hugdahl for this disturbance in the case of rapidly potential to impaire cognitive function. Such Correspondence to: Dr expanding haematomas are well understood, impairments may well contribute to the Knut Wester, Department and may be related to changes in general or patient's incapacity, but are not easily shown of Neurosurgery, Haukeland Hospital, N-5021, Bergen, local tissue perfusion. The reduced cerebral by a clinical neurological examination. To Norway. perfusion may be due to raised intracranial date, subtle cognitive impairments associated Received 3 January 1995 pressure, complicated by the presence of with intracranial expansions have received and in revised form 3 April 1995 oedema, itself a mass lesion, changes in much less attention than the more dramatic Accepted 19 April 1995 cerebrovascular reactivity, or the diffusion of and easily recognisable overt neurological 294 Wester, Hugdahl J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.59.3.293 on 1 September 1995. Downloaded from symptoms and findings. Indeed, there are few one patient (4) with a recent history of head reports dealing with cognitive functions in trauma, a subchronic subdural effusion/ patients with arachnoid cysts. Lang et al3 haematoma overlying the cyst was drained found a reduced ability to learn and memorise separately before the preoperative dichotic lis- hemisphere specific material in patients with tening tests and the shunt operation that middle fossa cysts, whereas other reports have eventually drained the cyst. failed to show cognitive impairments in such patients.'5 24 CONTROL GROUPS If cognitive deficits could be shown in Seven patients with arachnoid cysts of the patients with otherwise "silent" cysts, and if right temporal fossa served as a control group cyst surgery improves these functions, the for the preoperative scores. As only three of indications for surgery may be expanded con- these patients were operated on statistical siderably, and the decision to operate would analyses of the effects of decompressive be taken on a broader basis. surgery in patients with right sided cysts could Nearly half of the arachnoid cysts occur in not be performed. the middle cranial fossa,' with a pronounced Healthy subjects (age <50 years) also preference for the left side.25 Most cysts there- served as normal controls in both the dichotic fore affect the speech dominant hemisphere. memory (n = 32), and the dichotic listening For this reason, two tests were chosen for the (n = 52) tests. present study, based on the dichotic listening technique.26 These tests are sensitive to differ- DICHOTIC LISTENING STIMULUS MATERIALS ences in hemispheric functions and in particu- AND TEST PROCEDURES lar probe left hemispheric verbal functions. We used a modified version of the dichotic Dichotic listening procedures have previously memory test described by Christianson et al.30 proved sensitive in reflecting changes in pro- Three different series of 10 nouns were pre- cessing of verbal stimuli produced by discrete sented two seconds apart to the right or the electrical stimulation of the ventrolateral left ear, with the same nouns played simulta- thalamus27 28 and in recovery of language func- neously backwards to the other ear. The tions after a .29 Moreover, a memory patients were asked to recall all items remem- version of the dichotic listening test was used bered for 30 seconds after each series of 10 by Christianson et aP' when investigating words. The results were averaged over the hemispheric specific memory impairments in three series, the maximum score for each ear two cases of localised head trauma. thus being 10. To control for possible learning effects due to repeated presentations of the dichotic memory test, three parallel versions Patients and methods of the test were used. There might, however, PATIENTS still be some learning of the test situation Thirteen consecutive patients (11 men, two itself. To control for this possibility, seven women) were included in the study as the patients with left sided cysts and three with a experimental group. To keep the material as similar cyst on the right side were tested (pre- homogenous as possible, only patients with operatively) more than once. cysts in the left temporal fossa were included. Preoperatively, each patient was tested at

Another inclusion criterion was clinical least once. Only the score from the first pre- http://jnnp.bmj.com/ improvement after surgery (experienced by all operative test was used as the preoperative the patients). Handedness was defined with score in the statistical analyses. For seven of the help of a Norwegian translation of the the patients operated on under local anaesthe- questionnaire developed by Raczkowski et al." sia, the immediate postoperative condition The patient had to indicate 13 of the 15 items was so good that it allowed systematic collec- performed with the right hand to be classified tion of data two or three times during the first as right handed. Two of the patients (1 and 7) postoperative week. The first of these postop- indicated preference for the left hand; the erative tests took place four hours after the on September 27, 2021 by guest. Protected copyright. others were classified as right handers. operation, except in patient 1 who was tested Hearing acuity was determined by a Tegner after 24 hours. The immediate postoperative screening audiometer. All patients had normal condition did not allow a similar systematic hearing, and patients with an imbalance in testing during the first postoperative week in hearing between the ears of more than 5 dB the patients operated on with a full cran- were not included in the study. iotomy under general anaesthesia. All the All patients were referred to surgery patients were tested when returning to the because of pronounced clinical symptoms. hospital for the routine follow up three to six Headache was the most prominent, present in months postoperatively. all the patients before operation. One patient In the dichotic memory test, the 32 control (1 1) had had epilepsy for many years, and two subjects showed equal recalls from the right patients had recently developed epileptic and left ears. (5 and 6). One of these (5) also The overall memory performance (mean of showed a slight right sided the recalls from the right ear and the left ear) although without dysphasia. Another patient were also calculated for analyses between the (3) had had a transient, slight right sided experimental group and the two control hemiparesis four months before the operation. groups, and between the results before and None of the remaining patients had experi- after operation in the experimental group. enced any gross neurological disturbance. In The patients were also examined with a Arachnoid cysts ofthe left temporalfossa: impaired preoperative cognition and postoperative improvement 295 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.59.3.293 on 1 September 1995. Downloaded from dichotic test emphasising verbal perception, SURGERY described in detail elsewhere.26 In this dichotic Five of the patients underwent a craniotomy listening test, the stimuli consisted of the six with fenestration of the cyst to the basal cis- stop consonants b, d, g, p, t, k, all paired with terns during general anaesthesia. The remain- the vowel a to form six consonant-vowel (CV) ing eight patients were operated on with an syllables (ba, da, ga, etc). The syllables were internal shunt procedure under local anaes- paired with each other for all possible combi- thesia. This procedure and the clinical results nations, thus yielding 36 dichotic pairs. The will be reported in detail elsewhere." Briefly, a dichotic tape consisted of three lists of 36 small craniectomy was made and the wall of dichotic randomly ordered CV pairs each. the cyst and the adjacent cortex were exposed. Each syllable had a duration of 320 ms, and The cyst membrane was opened at the edge, synchronisation of onset between channels and an angled Holter ventricular catheter was performed for both the consonant and inserted into the cavity. The distal end of the vowel segment onsets. The interstimulus catheter was placed in the subdural space interval was 4 ± 1 s. overlying normal cortex, thus allowing the In the dichotic listening test, the patients cyst fluid to be drained into the subdural were tested in three different conditions. In compartment. This procedure reduced or the non-forced (NF) condition they were sim- eliminated the symptoms in seven patients, ply instructed to report freely all the syllables and proved sufficient as the only treatment in they heard. In the forced right (FR) or forced six. In one patient (5) with a large cyst, the left (FL) conditions, they were instructed to internal shunt operation caused a near com- attend to and report only what they heard in plete collapse of the cyst, followed by consid- the right or left ear."2 erable clinical improvement. This collapse The stimuli for the dichotic listening and was associated with the development of a sub- memory tests were played to the patient from a dural haematoma before the planned follow minicassette player through plug in type ear- up. The follow up data presented for this phones. The intensity of the output from the patient were therefore obtained after removal earphones were on average 75 dBA (repeated of this haematoma. In the last patient (3), the measurements) when tested with a sound operation induced a contralateral, expanding level meter. subdural effusion. The shunt was therefore To facilitate comparisons with other stud- transformed to a conventional cystoperitoneal ies, the raw scores were transformed to per- shunt, resulting in an immediate improve- centage scores. To evaluate any change in ear ment. The postoperative scores reported for advantage for both the dichotic listening and this patient are therefore those obtained after the dichotic memory tests, a laterality index the shunt revision. was calculated according to the formula: All the patients experienced a postoperative clinical improvement, and CT at the three to (RE-LE)/(RE+LE) x 100 six months follow up showed reduction of the cyst volumes in all the patients except two (3 where RE and LE reflect the recalls from the and 6). right and the left ears respectively. This yields a positive score for right ear advantage (REA),

a negative score for a left ear advantage Results http://jnnp.bmj.com/ (LEA), and zero for no ear advantage (NEA). MEMORY The laterality index compensates for individ- Table 1 shows the performance in the ual differences in overall performance. dichotic memory test. Ten of the 13 patients showed better recall from the left ear (LE) than from the right ear (RE) in the preopera- Table 1 Datafrom 13 patients treated, with clinical improvement, for arachnoid cysts in tive dichotic memory test, with a significant the left temporalfossa showing the size (type) of the cyst, the type ofoperation, and left ear advantage (LEA) for the group as a preoperative and postoperative scores for correct recallfrom right (RE) and left (LE) ear in = < on September 27, 2021 by guest. Protected copyright. the dichotic memory task whole (RE 3.5 v LE 4-6, t(12) 2.84, P 0-01). These preoperative scores differed sig- Preoperative Follow up Patient No Cyst type* Operation RE LE RE LE nificantly from the scores obtained in the nor- mal control group (n = 32; RE 5.9 v LE 5-9), 1 II-III Shunt 3-0 < 5 0 (4 0) 5-0 > 4-3 (4-7) 2 II Shunt 3-0 < 4-0 (3 5) 4 0 - 4-0 (4 0) both with respect to overall memory perfor- 3 III Shunt 4-3 < 5-3 (4 8) 6-0 > 5-3 (5-7) mance (4 1 v 5-9 for the patient and control 4 III Shunt 4-3 < 6-3 (5-3) 5-0 < 5-7 (5 3) = < 5t II-III Shunt 1-3 < 4-7 (3-0) 6-0 < 6-7 (6 3) groups respectively, t(43) 3-65, p 0-01), 6 I-II Shunt 3-5 > 3-2 (3 3) 5 0 > 4 0 (4 5) and the presence of an LEA in the patient 7 II-III Craniotomy 7-7 > 6-3 (7 0) 8-7 > 7-3 (8-0) = < 8 III Shunt 1-3 < 4-7 (3 0) 5-7 > 4-3 (5-0) group (t(43) 2 01, P 0-01). 9 II Craniotomy 1-7 < 3-7 (2-7) 3-3 < 5-3 (4-3) The preoperative memory ear advantage 10 II-III Craniotomy 4 0 < 5 0 (4-5) 5-7 < 6-7 (6-2) 11 II Craniotomy 5 0 > 4-3 (4 7) 6-3 > 4-3 (5 3) scores in the 13 patients with left sided cysts 12 I-II Shunt 4-0 < 4-3 (4 2) 5-7 < 6-7 (6 2) (table 1) were also significantly different from 13 II Craniotomy 2-3 < 3-3 (2 8) 5-3 > 3.3 (4 3) those of the seven control patients with cysts Total 3-5 < 4-6 (4-1) 5-5 > 5-2 (5 4) in the right middle fossa, who as a group = Scores in parenthesis indicate the overall performance as the means of right and left ear recalls. exhibited an REA (RE 3.9 v LE 3-5; t(18) *According to the classification of Galassi et al of middle fossa arachnoid cysts, type I is the 2-69, P < 0-05). smallest, situated entirely within the sylvian fissure. Type III is the largest cyst type, also extending over the cerebral convexity.39 At follow up, the preoperative LEA of the tLost to three to six months follow up because he developed a left subdural chronic haematoma experimental group disappeared for all com- two months after the shunt operation. The data listed under follow up for this patient are there- fore those obtained in a test two days after the evacuation of this haematoma through a burr parisons, with an improvement of the right ear hole. performance in all the patients (table 1). The 296 Wester, Hugdahl J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.59.3.293 on 1 September 1995. Downloaded from Table 2 Dichotic memory data (raw scores) from seven local anaesthesia patients where there was no significant difference between the immediate postoperative condition was so good that it allowed early (four hours and three to seven days) postoperative testing the results from the first and last tests. This was true both for overall memory perfor- Preoperative 4 hours 3-7 days Follow up Patient No RE LE RE LE RE LE RE LE mance and ear advantage, and also when patients with cysts on the left and the right 1 30 < 50 (40) 30 <40 (35)* 50> 27 (38) 50 > 43 (47) 2 30 <40 (35) 3-3<37 (35) 40<4-3 (42) 40 -40 (40) side were analysed separately. 3 4-3 < 5-3 (48) 57 > 43 (50) 53 > 47 (50) 6-0> 53 (57) The dichotic memory test seemed sensitive 4 4-3 < 6-3 (5-3) 5-0 < 5-3 (5 2) 6-0 > 5-7 (5-8) 5 0 < 5-7 (5 3) 5 1-3 < 4-7 (3-0) 5-7 > 4-7 (5 2) 7-7 > 6-7 (7-2) 6-0 < 6-7 (6 3) not only in disclosing preoperative impair- 6 35 > 32 (33) 43 > 30 (37) 40 > 3.3 (37) 50 > 40 (45) ments and postoperative improvements, but 12 4 0 < 4-3 (4 2) 5-7 > 3.3 (4-5) 4-7 < 5-3 (5-0) 5-7 < 6-7 (6-2) also treatment failures. In one patient (3), the Total 3-3 < 4-7 (4 0) 4 7 > 4 0 (4 4) 5-2 > 4.7 (4 9) 5-2 - 5-2 (5 2) shunt operation caused an immediate and *Results from 24 hour test, as four hour test was not performed. pronounced improvement in the dichotic memory test performance. During the first postoperative week, it became clear that this improvement was only temporary, as the ini- tial postoperative REA disappeared at the sixth day (table 3). At this time there was no difference between the laterality index before other indication of the shunt failure that and after operation was significant (- 11 1 v weeks later necessitated a shunt revision. 2-8, t(12) = 3.28, P < 005). The patients also improved their overall PERCEPTION memory performance postoperatively. At the The patients were also tested with the time of follow up, 12 patients had improved dichotic listening test, emphasising laterality their overall performance, whereas it for perception of dichotically presented CV remained unchanged in the last patient. The syllables. Table 4 summarises the results. group average increased from a preoperative Preoperatively, the group displayed a weak score of 4-1 to 5A4 at follow up (table 1).The and statistically non-significant LEA during increase in overall performance was signifi- the NF test. In normal controls, a significant cant (t(12) = 5 54, P < 0 001). REA is seen.26 The ear advantages varied con- The seven patients operated on under local siderably between the patients. The results in anaesthesia showed rapid improvement dur- the NF test differed, however, significantly ing the first postoperative week (table 2). from those of the normal control group There was a significant improvement of the (n = 52) for the laterality index scores as well overall memory score from the preoperative as total number of correctly perceived sylla- test to the postoperative tests (F(3,18) = bles. t Tests showed both the comparisons to 4 70, P < 0 05). Further tests (Newman- be significant (t(63) = 8-79, P < 0 001 and Keuls) showed that the significant improve- t(63) = 6-39, P < 0 001 respectively). ment occurred three to seven days after the The preoperative performance during the operation, and at the follow up control (all FR and FL tests were below normal on both P < 0 05). sides.32 As a group, the patients were able to There was also a rapid postoperative direct their attention to and increase their change in the ear advantage in these patients responses from the right and the left ear.

(table 2). The ear advantage in the memory Their scores were significantly below those of http://jnnp.bmj.com/ test changed significantly from a preoperative the normal control group, however, with LEA to an REA during the first two postoper- respect to both the laterality indices and the ative tests (at four hours and seven days) and a absolute number of correctly perceived sylla- no ear advantage (NEA) at follow up were bles (t(63) = 4-27 and 3-16 for the FR and FL also significant (F(3,18) = 4-83, P < 0 05). conditions respectively; P < 0.01). The Newman-Keuls test showed that the The cyst operations did not change the changes were significant for all three compar- non-forced dichotic listening pattern in any isons (all P < 0 05). These comparisons were significant way, and the distinct REA seen in on September 27, 2021 by guest. Protected copyright. performed on laterality index scores as normal subjects was not seen in the postoper- described. In the 10 patients who were tested ative controls either. In the forced attention preoperatively more than once to control for tests, the operation caused significant possible learning effects of repeated testing, changes. In the FR test at follow up, the patients displayed the expected superiority (advantage) from the right ear (to which attention was directed). The scores from that ear were significantly higher than the scores obtained in the preoperative FR and the post- Table 3 Individual dichotic memory scores from the postoperative period after thefirst, unsuccessful, operation in patient 3 operative NF tests, and the scores were no longer different from those of the normal con- Postoperative trol group in the similar (FR) situation. The Preoperative 4 hours 24 hours Day 6 same general response pattern (with an LEA) RE LE RE LE RE LE RE LE was seen in the FL condition. Comparing the 4-3 < 5-3 (4-8) 5-7 > 4-3 (5 0) 5-7 > 4-7 (5-2) 3-3 < 4-0 (3-7) postoperative laterality indices with the preop- Note the rapid nornalisation of the response pattern and overall performance (in parentheses) that erative indices for each of the two forced lis- was evident four hours after the operation. The right ear superiority was also present the next tening conditions (FR, FL), showed day but disappeared on the sixth postoperative day, indicating the shunt failure that was verified = < later. The immediate postoperative normalisation possibly reflects a temporarily lowered intra- significant changes (t(12) 2-15, P 0-05, cystic pressure after the first operation. and 1-83, P < 0-05, respectively). Arachnoid cysts ofthe left temporalfossa: impaired preoperative cognition and postoperative improvement 297 J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.59.3.293 on 1 September 1995. Downloaded from Table 4 Data (% correct reports) from the dichotic listening test, coUected in three different test situations Non-forced (NF) Forced nght (FR) Forced left (FL) Preoperative Follow up Preoperative Follow up Preoperative Follow up Patient No RE LE RE LE RE LE RE LE RE LE RE LE 1 47 > 43 47 > 40 63 > 17 63 > 23 50 > 40 40 < 47 2 57>40 33<67 67>23 70>30 27<60 10<90 3 43>50 47<50 40<47 60>37 60>40 50>43 4 27 < 73 47 - 47 47 > 27 67 > 7 13 < 47 27 < 60 5 53>40 50>47 37<53 57>33 40<57 23<70 6 63>33 47>40 67> 13 60>23 60>40 30<57 7 43-43 40<53 73> 17 80> 7 17<73 7<60 8 23 < 40 47 > 37 27 < 47 43 - 43 27 < 43 43 < 47 9 23<30 17- 17 30-30 27>23 13<33 13<37 10 30<40 43>37 50>20 60>20 23<43 27<57 11 30>23 30-30 47> 17 47>27 23<33 33<37 12 20<37 57>23 20<37 63>20 27<33 30<57 13 50 - 50 40 < 60 50 > 40 67 > 30 10 < 67 17 < 83 Total 39 < 42 42 - 42 47 > 30 59 > 25 30 < 47 27 < 57 Controls 53 > 41 62 > 26 30 < 56 (n = 52) In the non-forced condition, the patients were instructed to report freely the syllables heard in either ear. In the forced right or forced left conditions, they were instructed to pay attention to, and report only the syllables presented to the right or the left ear. Note the improvement in the forced conditions.

Discussion with other locations in the left or the right In the present study, dichotic listening tech- hemisphere, different tests must be selected. niques emphasising memory and perception Normal adults have the ability to direct showed lateralised cognitive deficits in their auditory attention to any of the two sides patients with arachnoid cysts of the left mid- in the dichotic listening test.'2 Our patients dle fossa. The impairments affected memory lacked this ability preoperatively and regained and the ability to direct attention in an audi- it after surgery, indicating that cerebral struc- tory, perceptual task, and disappeared after tures close to the left sylvian fissure are instru- decompressive cyst surgery. Normalisation of mental in an auditory attention mechanism, the memory functions occurred within hours and not only important for perception from or days. the contralateral right ear. These findings may well be explained within Kimura's model for DICHOTIC LISTENING AND MEMORY dichotic listening.35 In her model, auditory These non-invasive techniques have previ- information from the left ear reaches the left ously proved sensitive in reflecting discrete mainly via the right temporal changes in language functions produced by lobe and the corpus callosum, thus being electrical stimulation of the brain,2728 in weakened and delayed compared with the patients with localised brain damage,'0'3'8 more direct input from the right ear. The and in recovery of language functions after a lesions in our patients may have disturbed the stroke.29 normal ability to enhance the weakened and The clinical and behavioural implications delayed information from the ipsilateral left of the cognitive impairments reported here and in some cases ear, also the perception http://jnnp.bmj.com/ remain uncertain, but they may mirror deficits from the contralateral right ear. that are of importance to the patient. In this context it is interesting to note that none of ARACHNOID CYSTS AND COGNITIVE our patients had experienced any gross prob- IMPAIRMENT lems with speech or memory; neither were Arachnoid cysts are space occupying intracra- such deficits disclosed by neurological exami- nial lesions, and the symptoms they cause are nation before surgery. often surprisingly moderate considering their The present results thus indicate that later- substantial volumes. One reasonable explana- on September 27, 2021 by guest. Protected copyright. alised neuropsychological tests may have the tion of the stable appearance and relative potential to disclose subtle, subclinical paucity of symptoms may be that the intra- cognitive impairments in patients with lesions cystic and intracranial pressures are only in the region of the left sylvian fissure. Some moderately raised, a common finding during earlier studies have failed to show cognitive operation. The pressure exerted on neigh- impairment in patients with arachnoid bouring cerebral structures is therefore proba- cysts,'524 whereas Lang et al23 found learning bly also moderate, although the physical and memory deficits for hemisphere specific displacement of the same structures may be materials in their patients. One reason for the massive. Whether the neurological and neu- contradictory results may be that the neuro- ropsychological deficits caused by arachnoid psychological tests used in these studies cysts are precipitated by an increased tissue differed, and that some of them possibly pressure or the displacement of brain tissue, lacked the appropriate specificity for the or a combination of these or other factors, hemisphere or brain region affected by the remain unsolved. cyst. Our tests were chosen specifically to There is every reason to assume that show dysfunction of temporal areas in the left arachnoid cysts in adults have affected the and the right hemispheres. Cognitive func- surrounding cerebral structures for many tions other than memory and perception may years. It would therefore be a reasonable also be impaired in these patients. For lesions assumption that the associated brain damage 298 Wester, Hugdahl J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.59.3.293 on 1 September 1995. Downloaded from and concomitant symptoms might be perma- surgical treatment of intracranial arachnoid cysts. Acta Neurochir 1983;67:215-29. nent, and refractory to any form of surgical 14 Gandy SE, Heier LA. Clinical and magnetic resonance correction. The rapid restoration of cognitive feature of primary intracranial arachnoid cysts. Ann Neurol 1987;21:342-8. functions in our patients after decompressive 15 Kunz U, Ruckert N, Tagert J, Dietz H. Clinical and neu- surgery shows that this is not the case. This ropsychological results after operative and conservative treatment of arachnoidal cysts of the perisylvian region. indicates that middle fossa arachnoid cysts Acta Neurochir 1988;Suppl42:216-20. may cause a reversible suppression of neu- 16 Dei-Anang K, Voth D. Cerebral arachnoid cyst: a lesion of the child's brain. Neurosurg Rev 1989:12:59-62. ronal function rather than a permanent 17 Robertson SJ, Wolpert SM, Runge VM. MR imaging of destruction of cerebral tissue. middle fossa arachnoid cysts: temporal lobe agenesis syndrome revisited. AJ7NR Am I Neuroradiol 1989;10: The present results may have implications 1007-10. for future preoperative considerations in 18 Holst S. Congenital intracranial arachnoidal cysts. Case reports and discussion of the pathogenesis. J Oslo City patients with arachnoid cysts. The cognitive Hosp 1965;15:113-20. improvement after decompression in these 19 Aicardi J, Bauman F. Supratentorial extracerebral cysts in infants and children. J Neurol Neurosurg Psychiatry 1975; patients is so important that it may lower the 38:57-68. threshold for operative treatment, even in 20 Choux M, Raybaud C, Pinsard N, Hassoun J, Gambarelli G. Intracranial supratentorial cysts in children excluding patients with moderate clinical symptoms. tumor and parasitic cysts. Child's Brain 1978;4:15-32. Consequently, specific neuropsychological 21 Lodrini S, Lasio G, Fornari M, Miglivacca F. Treatment of supratentorial primary arachnoid cysts. Acta Neurochir test batteries that tap lateralised functions 1985;76: 105-10. should be developed for clinical use. Our tests 22 Marinov M, Undjian S, Wetzka P. An evaluation of the surgical treatment of intracranial arachnoid cysts in chil- were sensitive to, and therefore suitable for dren. Child's Nerv Syst 1989;5:177-83. probing asymmetric hemisphere functions 23 Lang W, Lang M, Kornhuber A, Gallwitz A, Kriebel J. Neuropsychological and neuroendocrinological distur- related to memory and language. For cysts bances associated with extracerebral cysts of the anterior with other locations or and middle cranial fossa. Eur Arch Psychiatr Neurol Sci (frontal, parietal, 1985;235:38-41. occipital), tests should be added for temporal 24 Gallassi R, Ciardulli C, Ferrara R, Lorusso S, Galassi E, and func- Lugaresi E. Asymptomatic large cyst of the middle sequencing, neglect, visuospatial cranial fossa. A clinical and neuropsychological study. tions. Eur Neurol 1985;24:140-4. 25 Wester K. Gender distribution and sidedness of middle We are indebted to Janniche Alvaer and Cathrine Hovland for fossa arachnoid cysts: a review of cases diagnosed with assistance in the collection of data. The research was computed imaging. Neurosurgery 1992;31:940-44. supported by grants from the Norwegian Medical Research 26 Hugdahl K, ed. Handbook ofdichotic listening: theory, methods Council (NAVF-RMF) and Nansen-fondet to KW and KH. and research. New York: Wiley and Sons 1988. 27 Ojemann GA. Enhancement of memory with human ventrolateral thalamic stimulation. Effect evident on a dichotic listening task. Appl Neurophysiol 1985;48:212-5. 28 Hugdahl K, Wester K, Asbjornsen A. The role of the left 1 Starkman SP, Brown TC, Linell EA. Cerebral arachnoid and right thalamus in language asymmetry: dichotic cysts. J7Neuropathol Exp Neurol 1958; 17:484-500. listening in Parkinson patients undergoing stereotactic 2 Rengachary SS, Watanabe I. Ultrastructure and patho- thalamotomy. Brain Lang 1990;39:1-13. genesis of intracranial arachnoid cysts. J Neuropathol Exp 29 Hugdahl K, Wester K, Asbj0rnsen A. Dichotic listening in Neurol 1981;40:61-83. an aphasic male patient after a hemorrhage in the left 3 Geissinger JD, Kohler WC, Robinson BW, Davis FM. fronto-parietal region. Intern J Neuroscience 1990;54: Arachnoid cysts of the middle cranial fossa: surgical 139-46. considerations. Surg Neurol 1978;10:27-33. 30 Christianson SA, Nilsson LG, Silfvenius H. Initial 4 Kumagai M, Sakai N, Yamada H, Shinoda J, Nakashima memory deficits and subsequent recovery in two cases of T, Iwama T, Ando T. Postnatal development and head trauma. ScandJ Psychol 1987;28:267-80. enlargement of primary middle cranial fossa arachnoid 31 Raczkowsky D, Kalat JW, Nebes R. Reliability and cyst recognized on repeat CT scans. Child's Nerv Syst validity of some handedness questionnaire items. 1986;2:211-5. Neuropsychologia 1974;12:43-7. 5 Rengachary SS. Intracranial arachnoid and ependymal 32 Hugdahl K, Andersson L. The "forced-attention cysts. In: Wilkins RH, Rengachary SS, eds. Neurosurgery, paradigm" in dichotic listening to CV-syllables: a com- Vol III. New York: McGraw-Hill, 2160-72. parison between adults and children. Cortex 1986;22: 6 Beltramello A, Mazza C. Spontaneous disappearance of a 417-32. http://jnnp.bmj.com/ large middle fossa arachnoid cyst. Surg Neurol 1985;24: 33 Wester K. Arachnoid cysts in adults. Experience with 181-3. internal shunts to the subdural compartment. Surg 7 Yamanouchi Y, Someda K, Oka N. (1986) Spontaneous Neurol 1995 (in press). disappearance of middle fossa arachnoid cyst after head 34 Kimura D. Some effects of temporal lobe damage on injury. Child's Nerv Syst 1986;2:40-3. auditory perception. Can J Psychol 1961;15:156-65. 8 Inoue T, Matsushima T, Tashima S, Fukui M, Hasuo K. 35 Kimura D. Functional asymmetry of the brain in dichotic Spontaneous disappearance of a middle fossa arachnoid listening. Cortex 1967;3:163-78. cyst associated with subdural . Surg Neurol 36 Eslinger PJ, Damasio H. Anatomical correlates of 1987;28:447-50. paradoxic ear extinction. In: Hugdahl K, ed. Handbook 9 Weber R, Voit T, Lumenta C, Lenard HG. Spontaneous of dichotic listening: theory, methods and research. New regression of a temporal arachnoid cyst. Child's Nerv Syst York: Wiley and Sons, 1988:139-60. on September 27, 2021 by guest. Protected copyright. 199 1;7:414-5. 37 Hugdahl K, Wester K. Dichotic listening studies of hemi- 10 Wester K, Gilhus NE, Hugdahl K, Larsen JL. spheric asymmetry in brain damaged patients. Intern J Spontaneous disappearance of an arachnoid cyst in the Neuroscience 1992;63: 17-29. middle intracranial fossa. Neurology 1991 ;41:1524-6. 38 Hugdahl K, Wester K, Asbjornsen A. Auditory neglect 11 Becker T, Wagner M, Hofman E, Warmuth-Metz M, after right frontal lobe and right pulvinar thalamic Nadjmi M. Do arachnoid cysts grow? A retrospective lesions. Brain Lang 1991;41:465-73. CT volumetric study. Neuroradiology 1991 ;33:341-5. 39 Galassi E, Tognetti F, Gaist G, Fagioli L, Frank F, Frank 12 Mayr U, Aichner F, Bauer G, Mohsenipour I, Pallua A. G. CT scan and metrizamide CT cisternography in Supratentorial extracerebral cysts of the middle cranial arachnoid cysts of the middle cranial fossa: classification fossa. Neurochirurgia (Stuttg) 1982;25:51-6. and pathophysiological aspects. Surg Neurol 1982;17: 13 Cilluffo JM, Onofrio BM, Miller RH. The diagnosis and 363-9.