does subjective improvement in adults with intracranial

CLINICAL ARTICLEJ Neurosurg 128:250–257, 2018

ArAchnoid cysts are benign, fluid-filled malforma-tions of the arachnoid tissue.20 Intracranial arach-noid cysts have a prevalence of around 2%, and

most are found incidentally.19 Individuals with arachnoid cysts may be asymptomatic or present with a wide range of neurological symptoms and signs.1 Symptoms related to arachnoid cysts are either secondary to hydrocepha-lus or due to compression of the adjacent neural tissue.1,27 Headache, dizziness or imbalance, and cognitive impair-

ment are among the most common symptoms associated with an arachnoid cyst.1 However, these symptoms are frequently encountered in the general population and are subjective and difficult to validate. Hence, the causal link between them and an arachnoid cyst is often uncertain or dubious. The indication for surgical treatment is therefore challenging in the case of the most common symptoms associated with arachnoid cysts.1,19

The aim of this study was to evaluate the clinical effect

ABBREVIATIONS FES(S) = Falls Efficacy Scale, Swedish version; MMSE = Mini–Mental State Examination; RAVLT = Rey Auditory Verbal Learning Test; ROCF = Rey-Osterrieth complex figure.SUBMITTED May 4, 2016. ACCEPTED September 28, 2016.INCLUDE WHEN CITING Published online February 17, 2017; DOI: 10.3171/2016.9.JNS161139.

Does subjective improvement in adults with intracranial arachnoid cysts justify surgical treatment?Katrin Rabiei, MD, PhD,1,2 Per Hellström, PhD,1 Mats Högfeldt-Johansson, MD,1,2 and Magnus Tisell, MD, PhD1,2

1Institute of Neuroscience and Physiology, Sahlgrenska Academy; and 2Department of Neurosurgery, Sahlgrenska University Hospital, Gothenburg, Sweden

OBJECTIVE Subjective improvement of patients who have undergone surgery for intracranial arachnoid cysts has justi-fied surgical treatment. The current study aimed to evaluate the outcome of surgical treatment for arachnoid cysts using standardized interviews and assessments of neuropsychological function and balance. The relationship between arach-noid cyst location, postoperative improvement, and arachnoid cyst volume was also examined.METHODS The authors performed a prospective, population-based study. One hundred nine patients underwent neu-rological, neuropsychological, and physiotherapeutic examinations. The arachnoid cysts were considered symptomatic in 75 patients, 53 of whom agreed to undergo surgery. In 32 patients, results of the differential diagnosis revealed that the symptoms were due to a different underlying condition and were unrelated to an arachnoid cyst. Neuropsychological testing included target reaction time, Grooved Pegboard, Rey Auditory Verbal Learning, Rey Osterrieth complex figure, and Stroop tests. Balance tests included the extended Falls Efficacy Scale, Romberg, and sharpened Romberg with open and closed eyes. The tests were repeated 5 months postoperatively. Cyst volume was pre- and postoperatively measured using OsiriX software.RESULTS Patients who underwent surgery did not have results on balance and neuropsychological tests that were dif-ferent from patients who declined or had symptoms unrelated to the arachnoid cyst. Patients with a temporal arachnoid cyst performed within the normal range on the neuropsychological tests. Seventy-seven percent of the patients who underwent surgery reported improvement, yet there were no differences in test results before and after surgery. Arach-noid cysts in the temporal region and posterior fossa did not influence the preoperative results of neuropsychological and motor tests. The arachnoid cyst volume decreased postoperatively (p < 0.0001), but there was no relationship between volume reduction and clinical improvement.CONCLUSIONS The results of this study speak against objectively verifiable improvement following surgical treatment in adults with intracranial arachnoid cysts.https://thejns.org/doi/abs/10.3171/2016.9.JNS161139KEY WORDS intracranial arachnoid cysts; neuropsychological testing; balance testing; cyst volume

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Can subjective improvement justify surgery for arachnoid cysts?

J Neurosurg Volume 128 • January 2018 251

of surgical fenestration of intracranial arachnoid cysts. In addition to the patients’ reported symptoms, cognitive and balance impairment were tested before and after surgery. Furthermore, we aimed to examine, using volumetrics, whether postoperative improvement and radiological re-duction in cyst volume were related.

MethodsPatient Population

All adults who had de novo cysts and were from the western region of Sweden were prospectively and con-secutively included in this study between December 2004 and December 2009. During this time, 125 patients (57 females and 68 males) between 18 and 83 years old (mean age 43 years) were included. The reasons for the initial imaging studies obtained in these patients were headache, dizziness or imbalance, trauma, visual disturbance, sei-zures, cognitive impairment, and focal neurological signs (Supplemental eTable 1).

Evaluations of images and referrals were performed by 2 senior neurosurgeons. All images were also reviewed by a neuroradiologist. One patient had an epidermoid cyst, and another patient was found to have a mega cisterna magna; both patients were excluded. Fourteen patients were excluded from further investigation due to the com-bination of a lack of symptoms and a small cyst, leaving 109 patients for further evaluation (Fig. 1).

The study was approved by the Ethics Committee for Medical Research at Gothenburg University, and all pa-tients gave their written consent to participate in the study.

Clinical ExaminationOne hundred nine patients were admitted for evalua-

tion in the Hydrocephalus Research Unit at Sahlgrenska University Hospital. The evaluations included MRI and neurological, neuropsychological, and physiotherapeutic examinations and were all based on predetermined fixed protocols. In addition to medical history and routine neu-rological examination, previous head trauma, hospital ad-missions, and complications during birth and trauma in early childhood and later in life were recorded. The neuro-logical examinations included the Mini–Mental State Ex-amination (MMSE), the Bingley visual memory test, and the identical forms test.5,6,31 If headache was present, ex-tensive headache anamnesis was part of the fixed protocol. At least 2 senior consultant neurologists were involved in the evaluation of the patients. Only patients with headache classified by the International Headache Society’s ICHD-2 (International Classification of Headache Disorders, 2nd edition) as “headache attributed to nonvascular intracra-nial disorder” or “headache related to space-occupying lesion” were considered to have arachnoid cyst–related headache.10

A fixed protocol was used for the MRI examinations of all patients with arachnoid cysts, including FLAIR-, dif-fusion-, and T1-weighted sequences, to allow both a dif-ferential diagnosis and volumetric measurements.

After the examinations, each case was discussed at a multidisciplinary conference, and patients whose symp-toms had no other explanation were offered surgery. Two

patients were excluded at this point, based on nascent vas-cular dementia and Parkinson’s dementia, leaving 107 pa-tients in the study (mean age 47.3 years, SD 16.2 years, range 18–76 years). Seventy-five patients were considered symptomatic and were offered surgical treatment, of whom 53 consented and 22 declined (Fig. 1). In 32 patients, the symptoms were found to be unrelated to the arachnoid cyst and were caused by a different underlying condition (e.g., tension headaches or migraine). Patient characteristics and test results are presented in Table 1.

The surgical method of choice was fenestration per-formed under general anesthesia. Patients who had under-gone surgery were evaluated using the same test battery and by the same research team following the same proto-cols 5 months postoperatively. The treating neurosurgeons were not part of the evaluation team. All new and residual symptoms and the patients’ reported outcome of surgery were noted by a neurologist who did not take part in the patient’s surgical treatment. MRI was repeated 5 months and 1 year postoperatively. Patients who declined surgery underwent follow-up by visiting the neurosurgical outpa-tient clinic.

Neuropsychological TestingThe same neuropsychologist (P.H.) examined all pa-

tients. A clinical interview including medical history, educational and occupational background, and patient symptoms preceded the neuropsychological testing. The psychometric tests performed were 1) target reaction time, 2) Grooved Pegboard test performed with the dominant and nondominant hand (Lafayette Instrumentation Co.), 3) the Rey Auditory Verbal Learning Test (RAVLT), 4) the Rey-Osterrieth complex figure (ROCF), and 5) the Swedish Stroop test.12,16,23,30 These tests measure different aspects of memory and recall: verbal learning and recall (RAVLT), visuospatial learning and recall (ROCF), at-tention and cognitive control (Stroop test and target reac-tion time), and manual dexterity (Grooved Pegboard test). These tests involve the function of many brain structures, including the temporal lobe region, anterior cingulate, the dorsolateral prefrontal cortex, and the head of the left cau-date.9,17,24 For neuropsychological tests, T-values based on the subject’s age and sex were calculated (Table 1).

Balance TestingAn experienced physiotherapist conducted the same

standardized tests in all patients. The examination started with an interview about the patient’s symptoms. The bal-ance tests performed were the expanded version of the Falls Efficacy Scale, Swedish version [FES(S)]; the Rom-berg test; and the sharpened Romberg test with open and closed eyes.11 The tests were performed twice, and the best test value was noted.

Cyst Volume MeasurementThe cyst volume was measured preoperatively and 5

months and 1 year postoperatively using FLAIR sequenc-es of 1.5-T MR images and OsiriX software version 6.5. The region of interest was manually outlined on each MRI slice and was calculated by the software.25


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K. Rabiei et al.

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Statistical AnalysisThe chi-square test was used for nonordered categori-

cal variables, Fisher’s exact test for dichotomous variables, and the Mann-Whitney U-test for continuous variables. For comparison over time, the Wilcoxon signed-rank test was used for continuous variables and the sign test for categori-cal variables. For comparisons between 3 groups, the Man-tel-Haenszel chi-square test was used for ordered categori-cal variables and the Kruskal-Wallis test for continuous

variables. All tests were 2-tailed; p < 0.05 was considered significant. The data were analyzed using version 9.4 of the SAS System for Windows (SAS Institute).

ResultsOverall, the patients exhibited a wide range of symp-

toms, including headache (60%), dizziness and/or imbal-ance (42%), cognitive impairment (17%), seizures (9%),

TABLE 1. Patient demographics and neuropsychological and balance testing

VariableSurgically Treated Patients

(n = 53) Declined Surgery

(n = 22)Patients w/ Symptoms Unrelated to AC

(n = 32) p Value

Age in yrs 46.5 (16.8) 48.9 (17.5) 47.4 (14.8) NSSex (F/M) 30/23 9/13 12/20History of trauma 15/56 (27%) 6/22 (27%) 9/32 (28%) NSCyst vol in ml 49.5 (52.4) 44 (36.7) 18 (20.8) NS*; 0.005†MMSE 27.6 (2.3) 28.6 (2.0) 30.0 (1.6) NSBingley test 7.2 (1.91) 7.3 (1.65) 7.8 (1.88) NSIdentical forms test 28.5 (11.7) 29.0 (11.6) 35.5 (14.4) NS*; 0.027†RAVLT 42.2 (13) 42.4 (13) 46.4 (13) NSRAVLT, delayed recall 45 (13) 45 (12) 50 (13) NSROCF test (range)‡ >40 (28 to >40) >40 (28 to >40) >40 (28 to >40) NSGrooved Pegboard test Dominant hand 41.2 (23.0) 36.4 (20.5) 49.8 (18.2) NS*; 0.012†§ Nondominant hand 42.1 (19.2) 23.5 (39.9) 47.6 (14.5) 0.007*; NS†Target reaction time 49.0 (14.2) 41.4 (14.7) 49.7 (12.1) NSSwedish Stroop test 49.1 (10.7) 52.1 (9.4) 54.0 (12.0) NSRomberg test 53.4 (16.9) 56.5 (12.3) 54.7 (15.9) NSSharpened Romberg Eyes open 49.1 (20.2) 49.6 (17.5) 49.0 (21.6) NS Eyes closed 21.1 (21.4) 22.8 (21.2) 22.9 (22.6) NSFES(S) score 5.49 (0.66) 5.44 (0.51) 5.22 (1.30) NSCyst location Temporal 16 14 16 Frontal 9 2 4 Parietal 3 0 1 Occipital 5 0 1 Posterior fossa 13 4 9 Suprasellar 1 0 0 Intraventricular 1 1 0 Perimesencephalic 1 0 1 Ambient cistern 1 0 0 Multilobular 4¶ 1** 0

AC = arachnoid cyst; NS = not significant.For continuous variables, means (SD) are presented unless indicated otherwise. Neuropsychological test scores are T-values. For all tests the scores were compared between surgically treated patients and patients who declined surgery and those whose symptoms were due to other causes. Also, patients who declined surgery and those whose symptoms were due to other causes were compared. Only statistically significant values are presented.* Difference between surgically treated patients and those who declined surgery.† Difference between surgically treated patients and those whose symptoms were unrelated to an arachnoid cyst.‡ The norms for the initial trial on the ROCF are presented in terms of cutoff values where “>40” means that the patient’s performance is less than 1 SD from the mean of healthy individuals and thereby considered normal. The exact T-values are not presented due to a heavily negatively skewed distribution in the normative sample.§ Patients whose symptoms were due to other causes performed significantly worse than patients who underwent surgery later and those who declined surgery.¶ One frontotemporal, 1 frontotemporoparietal, and 2 temporoparietal.** Temporoparietal.




visual disturbance (7%), and focal neurological symptoms (6.5%) (Table 2). The reported frequency of head trauma was the same in all 3 groups (27%–28%).

Headache was as prevalent in patients who opted for surgical treatment as in patients with symptoms unrelat-ed to the arachnoid cyst (p = 0.96), but less prevalent in those who declined surgical treatment (p = 0.007). The frequency of the other symptoms did not differ between the 3 patient groups (Table 2).

Surgically Treated PatientsOf the 53 patients who underwent surgical treatment,

50 underwent open microsurgical fenestration and 3 un-derwent endoscopic fenestration. Shunting was performed after the procedure in 4 patients because of concomitant hydrocephalus.

Eleven patients (21%) suffered 15 complications, of which 13 were transient and 2 caused permanent sequelae (3.8%). Six additional surgical procedures were performed to treat the different complications.

The transient complications consisted of epidural hema-toma (1 case), subdural hematoma (2 cases), subdural hy-groma (2 cases), CSF leakage (3 cases), meningitis (1 case), occipital neuralgia (1 case), pseudomeningocele (1 case), and transient aphasia related to edema in the left temporal

lobe region (1 case). One patient with persistent CSF leak-age (who initially underwent surgery in the posterior fossa) underwent reoperation with endoscopic third ventriculos-tomy and, later on, ventriculoperitoneal shunting.

The permanent complications consisted of a venous in-farction in combination with intracerebral hematoma fol-lowing ligation of frontal bridging veins, which resulted in complete damage to the right frontal lobe. The second patient developed epileptic seizures following a subdural empyema that was surgically evacuated with removal of the bone flap and reoperation with cranioplasty.

At the 5-month follow-up, 41 (77%) patients described their overall symptoms as improved, 8 (15%) considered their symptoms to be unchanged, and 2 (4%) were worse. One patient was lost to follow-up and another did not an-swer this question. However, when comparing the number of symptoms before and after surgery, only 23 (43%) pa-tients were found to have complete remission of at least 1 preoperative symptom, while 26 (49%) were unchanged and 3 (6%) had more symptoms than before surgery. Pa-tients reported improvement of headache and dizziness but not of cognitive symptoms (Table 3).

No arachnoid cyst location could be associated with patient-reported improvement. Furthermore, no arachnoid cyst location could be associated with improvement de-fined as remission of at least 1 clinical symptom. Neither

FIG. 1. Flowchart showing the patient population. AC = arachnoid cyst.


K. Rabiei et al.


headache nor dizziness was associated with a particular arachnoid cyst location.

Neuropsychological TestingThe neuropsychological test results of the surgically

treated patients were similar to those of patients who de-clined or had symptoms unrelated to the arachnoid cyst. Overall, the test results were within the reference range for all groups (Table 1). Following surgery, the patients did not improve on any of the test variables except perhaps target reaction time (p = 0.048) (Table 4). Furthermore, there were no differences in the test results of patients who reported cognitive impairment and those who did not. Additionally, patients with temporal arachnoid cysts performed within the normal range of neuropsychological tests, and their test results were similar to those of patients with arachnoid cyst in other locations.

Balance TestingThe results of the balance tests were similar between

the patients who underwent surgery and those who de-clined surgery or had symptoms unrelated to their arach-noid cyst (Table 1). The patients who underwent surgery did not improve on any of the test parameters (Table 4). Furthermore, the results of the balance tests did not dif-fer between those with posterior fossa arachnoid cysts and those with arachnoid cysts in other locations. A temporal location was not found to affect the results of the balance tests.

Patients reporting dizziness/imbalance preoperatively exhibited worse results on the Romberg test (p = 0.004) and the sharpened Romberg tests with the eyes open (p = 0.012) and closed (p = 0.0081), but not on FES(S) (p = 0.085), compared with those who did not experience this symptom. These patients did not improve on any of the performed tests postoperatively. Preoperatively, patients with posterior fossa arachnoid cysts performed similarly on the balance tests to patients with an arachnoid cyst in other locations. However, postoperatively, they performed worse than patients with an arachnoid cyst in other loca-tions on the Romberg test (p = 0.0003) and the sharpened Romberg test with the eyes open (p = 0.015) but not with the eyes closed (p = 0.17), and FES(S) (p = 0.51). The dif-ference between preoperative and postoperative values within the group of patients with posterior fossa cysts was statistically significant only for the Romberg test (p = 0.050).

Cyst Volume MeasurementsThe mean preoperative cyst volume in surgically

TABLE 2. Major complaints among all patients

Variable

No. of Patients (%)

Total (n = 107)

Surgically Treated Patients (n = 53)

Declined Surgery (n = 22)

Patients w/ Symptoms

Unrelated to AC (n = 32)

Headache 36 (68) 7 (32)* 21 (66) 64 (60)Dizziness or imbal-

ance23 (43) 11 (50) 11 (34) 45 (42)

Cognitive impairment 11 (20) 4 (18) 3 (9) 18 (17)Visual disturbance 5 (9) 0 (0) 2 (6) 7 (7)Seizures 6 (11) 3 (14) 1 (3) 10 (9)Focal neurological

symptoms4 (7) 1 (5) 2 (6) 7 (7)

Other symptoms 6 (11) 0 2 (6) 8 (7.5)No subjective symp-

tomsNA 0 2 (6) 3 (3)

NA = not applicable.* Headache was less prevalent in patients who declined surgery (p = 0.007) than in those who opted for surgery and those in whom the symptoms were considered to be due to other causes.

TABLE 3. Major complaints among surgically treated patients before and after surgery

Variable

No. of Patients (%)p

ValuePreop Symptom

(n = 53)Postop Symptom

(n = 52)

Headache 36 (68) 19 (37) 0.0003Dizziness or imbalance 23 (43) 10 (19) 0.005Cognitive impairment 11 (20) 10 (19) NSVisual disturbance 5 (9) 2 (4) NSSeizures 6 (11) 2 (4) NSFocal neurological

symptoms4 (7) 1 (2) NS

Other symptoms 6 (11) 9 (17) NSNo subjective symptoms NA 8 (15) 0.02

TABLE 4. Neuropsychological and balance test results before and after surgery in surgically treated patients

Variable Preop Value Postop Value p Value

Cyst vol in ml 49.5 (52.4) 31.0 (50.9) <0.0001RAVLT, total 42.2 (13) 42.7 (12) 0.93RAVLT, delayed recall 45.8 (13) 45.8 (13) 1.00Grooved Pegboard test Dominant hand 41.2 (23.0) 38.1 (22.9) 0.56 Nondominant hand 42.1 (19.2) 34.2 (27.0) 0.29Target reaction time 49.0 (14.2) 45.4 (12.5) 0.048Swedish Stroop test 47.1 (10.7) 49.1 (12.4) 0.80ROCF (range)* >40 (28 to >40) >40 (28 to >40) 0.63Romberg 53.4 (16.9) 53.8 (16.4) 0.83Sharpened Romberg Eyes open 49.1 (20.2) 43.2 (24.0) 0.41 Eyes closed 21.1 (21.4) 25.2 (24.3) 0.51FES(S) 5.49 (0.66) 5.48 (0.80) 0.74

Mean values (SD) are presented unless indicated otherwise. The mean values are T-values. For comparison between groups, the Mann-Whitney U-test was used for continuous variables.* The norms for the initial trial on the ROCF are presented in terms of cutoff values where “>40” means that the patient’s performance is less than 1 SD from the mean of healthy individuals and thereby considered normal. The ex-act T-values are not presented due to a heavily negatively skewed distribution in the normative sample.




treated patients was 49 ml (SD 52.4 ml, median 30 ml). At follow-up, this volume was reduced to 31 ml (SD 50.9 ml, median 11 ml) (p < 0.0001). The cyst volume further decreased to 29 ml (SD 49.4 ml, median 9 ml) at the 1-year radiological follow-up (p = 0.0005). Clinical improvement was not related to a reduction in cyst volume (p = 0.71).

Patients Who Declined Surgery and Patients With Symptoms Unrelated to the Arachnoid Cyst

Of the 22 patients who declined surgery, 11 (50%) re-ported spontaneous improvement in their presenting symp-toms within 3 months and did not desire further follow-up. Eight patients’ conditions improved over the following year. The remaining 3 patients eventually underwent surgery.

Neuropsychological Testing and Balance TestingThere were no differences in performance on the Rom-

berg test, sharpened Romberg tests with the eyes open and closed, FES(S), target reaction time, RAVLT, ROCF, and Swedish Stroop test between the patients who declined surgery and those who underwent surgery and patients with symptoms unrelated to arachnoid cyst. Patients who declined surgery performed better than patients who un-derwent surgery on the Grooved Pegboard test performed with the dominant hand. At the same time, patients who were not offered surgery performed worse than the other groups on the same test (Table 1).

Cyst Volume MeasurementsThe mean cyst volume in patients who declined surgery

was 44 ml (SD 36.7 ml, median 27.8 ml) and did not dif-fer from patients who underwent surgery (p = 0.96). Pa-tients with symptoms unrelated to their arachnoid cyst had a smaller mean arachnoid cyst volume of 18 ml (SD 20.8 ml, median 9.8 ml) than patients who accepted surgical treatment and those who declined surgery (p = 0.0025 and p = 0.0006, respectively).

DiscussionIn this prospective study on adult patients with arachnoid

cysts, we found no differences in the test results of patients considered to be symptomatic and those whose symptoms were not considered to be related to their arachnoid cyst. Furthermore, arachnoid cyst location did not influence the results of any of the performed tests. The majority of the surgically treated patients (77%) rated themselves as having improved at follow-up. However, only 43% had complete remission of at least 1 preoperative symptom. Furthermore, the test results did not improve in those who underwent surgical treatment. Half of the patients who de-clined surgical treatment (50%) improved spontaneously within 3 months and 86% within the 1st year.

The main strength of our study is the prospective de-sign, the defined population, the extensive preoperative and postoperative examinations, and the volumetric mea-surement of the arachnoid cyst volume. However, the study is uncontrolled, and the follow-up time is relatively short.

A primary arachnoid cyst is a benign condition and is often found incidentally, with a reported prevalence of 2% and no association with the most common symptoms

ascribed to it in the general population.19 The increased use of medical imaging in the assessment of patients re-porting multifactorial and prevalent symptoms has led to an increase in the number of identified arachnoid cysts. In such cases, clinical evaluation is challenging and com-plex.22,26,28,29 In fact, although most neurosurgeons agree that surgery should be reserved for symptomatic patients, arachnoid cyst size has been shown to be the most impor-tant predictor of surgical treatment.3

Headache, the most common symptom in arachnoid cyst, is also one of the most common and disabling condi-tions of humankind.8,15 In our study, headache was the most frequently reported symptom in the group of patients who underwent surgery, whereas it was less prevalent among those who declined surgery. The headache was improved in a significant number of our patients (47% of those who complained of headache preoperatively did not suffer from headache at follow-up). This beneficial effect may be due to our multidisciplinary approach to patient evaluation, with the involvement of experienced neurologists and a phys-iotherapist (evaluation of exertion headache). However, we cannot rule out the placebo effect of surgery on symptom improvement during this relatively short-term follow-up.7

Dizziness or imbalance, the second most common symptom in arachnoid cyst, is yet another complex and multifactorial condition.14,32,33 Our patients reported a high rate of improvement regarding this symptom postopera-tively (57% of those who suffered preoperatively no longer reported dizziness or imbalance during follow-up). How-ever, their test results did not improve postoperatively. In the arachnoid cyst patients in our study, the dizziness/im-balance may have had causes other than the arachnoid cyst, and, if at all related to the arachnoid cyst, this symptom did not respond to surgical decompression despite subjec-tive reports of improvement. Furthermore, perhaps surpris-ingly, the performance of patients with a posterior fossa arachnoid cyst did not differ from those with arachnoid cysts in other locations preoperatively, but had deteriorated following surgical treatment. However, the difference be-tween pre- and postoperative results within this group was statistically significant only on the Romberg test, possibly due to the small number of patients.

Complaints of cognitive disturbances are often associ-ated with arachnoid cysts and have been used as a justi-fication for surgical treatment, especially in the case of temporal arachnoid cysts.21 Our results do not show that a temporal arachnoid cyst causes cognitive disturbances but rather confirm the quiescent nature of arachnoid cysts.13 Furthermore, following surgery, the only significant dif-ference in the neuropsychological test results of surgically treated patients was impaired performance on the target reaction time test.

The high improvement rates reported in previous studies have also been used to justify surgical treatment, despite the risk of complications. The evaluation of im-provement diverges considerably. In accordance with most previous studies, we found a high rate of improvement (77%) when asking patients about the evaluation of their symptoms. However, the rate of improvement drops to less than half when total remission of at least 1 symptom is required. We speculate that patient-reported improvement rates, at least in part, might reflect the impact of anxiety of


K. Rabiei et al.


being diagnosed with an intracranial lesion and the subse-quent postoperative relief that is unrelated to the arachnoid cyst itself.27 In fact, in our recent study on children with arachnoid cysts, almost all patients or parents considered the surgery worthwhile, based on the preoperative anxi-ety connected to the diagnosis of the arachnoid cyst and regardless of the impact of surgery on their symptoms.18

The high rate of improvement may also be spontane-ous.1 In our study, 86% of the 22 patients who declined surgery eventually improved. Since there was no differ-ence in arachnoid cyst volume between these patients and those who chose surgery (p = 0.96), this improvement rate, similar to that of many surgical series, is remarkable. Fur-thermore, we found that improvement was unrelated to the arachnoid cyst volume in the patients who underwent sur-gery, making the disappearance or decompression of the arachnoid cyst as a measure of surgical outcome pointless.

In Sweden, the rate of surgery for intracranial arach-noid cyst in adults has almost doubled over the past 5 years compared with the study period, according to the Swedish National Board of Health (The National Board of Health and Welfare, www.socialstyrelsen.se/english, accessed on March 25, 2016) (Supplemental eFig. 1). The increasing use of radiological examinations, together with a common radiological finding, frequently encountered symptoms as-cribed to it, and a high reported rate of improvement in surgical series are perhaps the underlying causes. In this study, surgery was offered to all patients in whom other causes of their symptoms were ruled out. Yet, the benign nature, and what is now known about the natural history of arachnoid cysts,1,2 together with the risk of serious com-plications associated with surgical treatment4 and the lack of verifiable improvement despite diminished cyst size, speak mainly against surgical treatment.

ConclusionsWe found no differences in the neuropsychological

and balance test results of patients with and those with-out symptomatic arachnoid cysts. Results on balance and cognitive performance tests did not improve in surgically treated patients, despite self-reported improvement and re-duction in the arachnoid cyst volume. The results of the study speak against objectively verifiable improvement af-ter surgical treatment in adults with intracranial arachnoid cysts.

AcknowledgmentsWe gratefully acknowledge Elisabeth Blomsterwall for physio-

therapeutic assessment of the patients and guidance regarding the interpretation of the balance tests performed, Roberto Doria Medi-na for volumetric measurements, all members of the Hydrocephalus Research Unit involved in the evaluation and patient care, especially Gudrun Barrows and Gunilla Ahl-Börjesson for coordination of the study and investigations involved and for extensive work on the patient database, and Cecilia Kjellman at Statistiska Konsultgrup-pen for the statistical analyses.

The study was supported by the Göteborg Foundation for Neurological Research (ISNF), Sahlgrenska University Hospital’s research foundations, The Göteborg Medical Society and Kristina Stenborg’s Foundation, Edit Jacobson Foundation, the Rune and Ulla Amlöv Foundation, Hjalmar Svensson’s Research Foundation, and the John and Brit Wennerström Foundation. The funders had

no role in the study design, the collection and analysis of the data, the data interpretation, or the writing of this paper.

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DisclosuresThe authors report no conflict of interest concerning the materi-als or methods used in this study or the findings specified in this paper.

Author ContributionsAcquisition of data: all authors. Analysis and interpretation of data: Rabiei, Hellström, Tisell. Drafting the article: Rabiei. Criti-cally revising the article: Rabiei, Hellström, Tisell. Reviewed submitted version of manuscript: all authors. Approved the final version of the manuscript on behalf of all authors: Rabiei. Study supervision: Tisell.

Supplemental Information Online-Only ContentSupplemental material is available with the online version of the article.

Supplemental eTable 1 & eFig. 1. https://thejns.org/doi/suppl/10.3171/ 2016.9.JNS161139.

CorrespondenceKatrin Rabiei, Institute of Neuroscience and Physiology, c/o Department of Neurosurgery, Sahlgrenska University Hospital, Blå stråket 5, vån 3, Gothenburg SE-413 45, Sweden. email: [email protected].




does subjective improvement in adults with intracranial

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