Arachnoid Cysts: Clinical and Surgical Management

Arachnoid Cysts: Clinical and Surgical Management gives a broad and updated presentation of the condition, including symptomatology, diagnostics, management and treatment. The book covers the effects of surgical treatment on clinical symptoms and the effects cysts have on cognition, as well as cognitive improvement after surgical cyst decompression. This book is written for researchers, residents and clinical practitioners in clinical neuroscience, neurology, neurosurgery, neuroradiology and pediatrics.

• Covers the symptomology and treatment of arachnoid cysts
• Describes impaired cognition associated with arachnoid cysts
• Identifies the advantages, disadvantages and results of different surgical approaches
• Provides valuable information to researchers, residents and clinical practitioners in clinical neuroscience, neurology, neurosurgery, neuroradiology and pediatrics

• Language: English
• Publisher: Academic Press
• Release date: Sep 27, 2017
• ISBN: 9780128143797

Book preview

States

Preface

Knut Wester

To my knowledge, this is the first textbook in English ever on arachnoid cysts (AC). Considering the fact that AC is the most common intracranial expansive condition in the general population, this absence of comprehensive literature is striking. Most probably it reflects the common attitude shared by many colleagues: that an AC is a congenital, benign condition that does not require attention unless it yields dramatic symptoms.

More often than for other intracranial conditions, relatively little high level evidence exists on ACs and how we should deal with them. Unfortunately, the majority of publications on the subject are case reports or case series with low level of evidence and consequently little to build recommendations on. However, there are also studies that have investigated AC related matters in larger cohorts and in a systematic fashion. In this book, emphasis is placed on such extensive and systematic reports when they exist, rather than on reports describing a few patients.

However, if a large collection of case reports point in the same direction, such evidence cannot be completely dismissed. Less weight must be put on experts’ opinions if they are based only on clinical experience achieved back in the time when any intracranial procedure was a risky undertaking, attitudes that have been conveyed to us from previous generations of colleagues without any questioning of the truth of the message in the meantime. It is my impression, after having read hundreds of publications in preparing this book, that this lack of systematically collected evidence in the past has allowed mindsets acquired decades ago to survive and maintain the status of truth, even if the basis of this wisdom is very weak, see e.g., Chapter 1, Arachnoid Cysts—Historical Perspectives and Controversial Aspects in Volume 1.

In an attempt to sort out what is the truth and what are myths and misconceptions (or whatever lies inbetween), we have asked a total of 43 international colleagues from 10 different countries on three continents, with views that we knew or assumed to be conflicting, to contribute to the chapters in this book. Some of these authors have vast clinical and scientific experience with the topic; others are less merited, but nevertheless have an interesting story to tell. The authors were asked to base their chapters on existing evidence and to indicate the evidence levels for their statements in the beginning of each chapter when possible. Otherwise they were given free hands, thus allowing opposing views to be exposed.

This liberal editorial attitude may well have resulted in conflicting or even confusing information, but so are the views and opinions of our colleagues; it is therefore of importance that they all are represented here in this book. Thus, my advice to the readers is simply to read and evaluate the conflicting evidence and in the end: make up your own minds—to do the best for our patients.

Due to the amount of available information, this textbook is published in two separate volumes. The present volume (Volume 2—Clinical and Surgical Management) gives information related to clinical practice: symptoms, diagnosis, and surgical treatment (techniques and outcomes). The last four chapters (17–20) focus on pediatric, spinal, and sport-related aspects of arachnoid cysts.

Guy Eslick, Professor of Cancer Epidemiology and Medical Statistics at The University of Sydney, Australia took the initiative for the book by suggesting that I write and edit a book on this topic. Without this initiative, for which I am very grateful, this book would never have materialized.

I would also like to express my gratitude to the editorial staff at Elsevier: Kathy Padilla and Melanie Tucker for their friendly and expeditious advice and assistance.

Part I

Clinical Diagnostic Aspects

Outline

Chapter 1 Intracranial Arachnoid Cysts and Headache

Chapter 2 Clinical Presentation, Symptoms, and Complaints

Chapter 3 Intracranial Arachnoid Cysts and Epilepsy

Chapter 4 Arachnoid Cyst and Visual Function

Chapter 5 Clinical Presentation, Symptoms and Complaints—What Matters

Chapter 6 Intracranial Arachnoid Cysts and Mental Functions

Chapter 1

Intracranial Arachnoid Cysts and Headache

Knut Wester¹,²,    ¹University of Bergen, Bergen, Norway,    ²Haukeland University Hospital, Bergen, Norway

Abstract

A literature search revealed 10 articles that gave information on the prevalence of headache in patients operated for an arachnoid cyst (AC). In these studies, headache emerged as the most common complaint, in most cases more frequent than the second most common—vestibular symptoms. The mean headache prevalence for the 636 AC patients included in these articles was 66.7%, ranging 31%–84%. Headache is reported more frequently in adults than in children, ranging 74.4%–84.2% (mean 77%) and 31%–60.5% (mean 48.9%), respectively. This difference is most likely deceptive, as the pediatric cases included many young children without sufficient language to report subjective complaints. Headache intensity is not correlated to the size of the cyst, but to the intracystic pressure. In a large prospective series three-quarters of the patients experienced a significant postoperative reduction of headache; in another large study about the same proportion reported no or only minimal postoperative headache. As is the case for other complaints, there was no correlation between postoperative reduction in cyst volume and headache improvement.

Keywords

Adults; arachnoid cyst; children; headache; prevalence

Outline

Abbreviation 3

Recommendations—Level of Evidence 4

Level I 4

Level II 4

Prevalence of Headache in AC Patients 5

Characteristics of AC-Associated Headache 6

Effects of Surgical Decompression on Headache 6

Adults 6

Children 7

References 7

Abbreviation

AC arachnoid cyst

Recommendations—Level of Evidence

Level I

There is no Level I evidence available concerning the topic dealt with in this chapter.

Level II

Headache is the most common preoperative complaint in operated arachnoid cyst (AC) patients; nearly three-quarters of these patients complain of headache.

Headache (and/or dizziness) contributes to the low quality of life (qol) that is found in AC patients.

Headache intensity is not correlated to the size of the cyst, but to the intracystic pressure.

Surgical cyst decompression leads to significant improvement, not only of the headache, but also qol; this improved qol is correlated to the reduction in headache, but not to the preoperative cyst volume or postoperative reduction of the cyst volume.

Arachnoid cyst is one of the most common intracranial conditions [1–5]; most of them are probably asymptomatic. In a literature search for large series of surgically treated patients, defined as comprising more than 25 patients, that have been published after the millennium shift, a total of 10 articles were retrieved that gave information on the prevalence of headache in the operated patients. In these studies, headache emerges as the most common complaint, in most cases more frequent than the second most common—vestibular symptoms (dizziness and nausea).

As headache in itself is a common complaint in the population [6], a causal relationship between the AC and this symptom cannot be taken for granted. However, if the headache disappears or is markedly reduced after surgical cyst decompression, a causal relationship is more likely. As will be apparent below, such postoperative effects on headache in AC patients have now been demonstrated in large series of patients; a causal relationship can therefore no longer be questioned.

When I first was confronted with AC patients with incapacitating headache in the early 1980s and had to make a decision on whether to perform surgical compression or not, there was little help to find in the literature to support a decision. However, as most ACs seemed to exert a mass effect on the surrounding structures and as other intracranial processes with mass effect cause headache, I assumed a causal relationship and decided to try decompression in these few patients, much against the advice of my seniors (don’t ever operate arachnoid cysts, the cyst is an incidental finding and has nothing to do with the headache, etc.). I started out—rather reluctantly to begin with—on the presumption that ACs could be the underlying cause of the complaint. After a few patients, we experienced that the headache disappeared or was markedly reduced after the operation in nearly all patients, thus encouraging a gradually more liberal attitude towards decompressive surgery. In later studies, including a relatively large prospective study from our department [7], we found - in our view - justification for this change of strategy, as the preoperative headache disappeared or was markedly reduced in about three-quarters of the patients.

The indications and enthusiasm for—alternatively the reluctance to—decompressing ACs surgically varies tremendously from one institution to another. As most published patient studies have been based on patients with complaints believed to be caused by an AC, it is conceivable that the prevalence of headache in these patient materials may differ, depending on the personal view of the authors. In addition, some studies only report the most debilitating symptom, whereas other authors list all complaints, thus allowing each patient more than one symptom.

Prevalence of Headache in AC Patients

In our department, we have published two large, nonoverlapping studies, comprising 156 [8] and 76 operated adult patients [7] with headache prevalence of 80.8% and 84.2%, respectively. In children we however found a much lower prevalence: 31% [9]. A similar prevalence, including the disproportion between adults and children, appears to be valid also for other large series.

When pooling the data from the 10 studies retrieved from the literature search [7–16], 424 of a total of 636 AC patients complained of preoperative headache, giving a mean headache prevalence of 66.7% in this pooled patient population. Some of these articles report only data from children [9,13–15]; others report only the prevalence in adults [7,8,16]. From these data headache appears to be more prevalent in adults than in children, ranging 74.4%–84.2% (mean 77%) and 31%–60.5% (mean 48.9%), respectively.

I don’t think that this difference between children and adults is real. The most probable explanation for this apparent dissimilarity may be that headache is a subjective symptom that is dependent on adequate, in most cases verbal, communication of the complaint to the surroundings. As the lower age in the child studies varied between 1 and 9 months, it is realistic to assume that a significant proportion of the children were unable to convey distinct information about headache.

Characteristics of AC-Associated Headache

Very little has been published on the characteristics of AC-associated headache; after having talked with and operated more than 400 AC patients, I believe I know the reason: it is simply impossible to recognize any headache features that are typical for AC. Even a unilateral headache may be on the wrong side, i.e., the opposite side to the cyst.

Only one study [7] has attempted to investigate these aspects, however without being able to really illuminate the case. Some of the patients describe the headache as constantly present; in others it comes in bouts or is present for periods of days or even weeks. The headache may be pulsating, stinging/burning, or perceived as a constant pressure, the latter being most common, described by 62%. A similar percentage describes diurnal variation, apparently increasing from morning to evening.

An interesting clinical observation, although not substantiated by any published results, is that the headache in some patients appears to be precipitated by physical events, such as a fall on a slippery surface or a long car ride on a bumpy road, etc. Maybe these events changed the gradient and a delicate equilibrium between the intracystic and the intracranial pressures.

It is a common misconception that small cysts are asymptomatic and that symptom reduction is dependent on postoperative reduction of the cyst volume. The latter may however be true for children, see below. The intracystic pressure seems to be the only parameter that is correlated to preoperative symptom intensity in AC, see Chapter 5, Clinical Presentation, Symptoms and Complaints - What Matters: Size, Location, or Intracystic Pressure?; whereas cyst size does not seem to be of importance [17].

Effects of Surgical Decompression on Headache

Relatively few of the large series quoted above report postoperative changes specifically for headache, and if they do, not always in a uniform and commensurable way. The message is however clear: headache improves or even disappears after decompressive surgery in the large majority of AC patients.

Adults

Mørkve et al. [7] reported the effect of cyst decompression on headache in the following way: at follow-up, 73.4% of the patients (adults) had a significant reduction in mean preoperative headache VAS score for the entire group, including those that did not improve, from a VAS score of 45.6 to 25.8 postoperatively. There was no correlation between postoperative reduction in fluid volume and clinical improvement. However, headache improvement seemed to be a prerequisite for the patients’ postoperative improved quality of life, as was the improvement of dizziness, see Chapter 16, Pre- and Postoperative Quality of Life in Arachnoid Cyst Patients.

Helland and Wester [8] did not study specifically the effects of surgery on headache, however in a very large population (156 patients) where the vast majority (74.4%) complained of strong headache, they reported disappearance or considerable improvement of the preoperative complaints in 80.6% of the patients. They too failed to demonstrate a correlation between radiological and clinical improvement in this population; a lack of such a correlation has also been described by Khan et al. [12].

Children

Kimiwada et al. reported an even better improvement rate in children: of the 13 children that complained of headache before surgery, the headache had disappeared in 12 and improved in one [13]. In another child study, Helland and Wester found that the headache had disappeared completely in 47% and was considerably reduced in another 40%. Only one child did not experience any improvement of the headache [9]. As opposed to the results obtained in adults, there appeared to be a correlation between postoperative reduction in cyst fluid volume and clinical outcome in children; children with the most pronounced volume reduction also experienced a better clinical outcome. To our knowledge, this correlation has, however, not been observed in other pediatric patient cohorts.

In a mixed population of children and adults, Couvreur [10] reported that 50% patients were pain-free at follow-up and that 80% of the patients exhibited a reduction of the preoperative headache VAS greater than 50%.

References

1. Al-Holou WN, et al. Prevalence and natural history of arachnoid cysts in adults. J Neurosurg. 2013;118(2):222–231.

2. Al-Holou WN, et al. Prevalence and natural history of arachnoid cysts in children Clinical article. J Neurosurgery-Pediatrics. 2010;5(6):578–585.

3. Eskandary H, et al. Incidental findings in brain computed tomography scans of 3000 head trauma patients. Surg Neurol. 2005;63(6):550–553.

4. Vernooij MW, et al. Incidental findings on brain MRI in the general population. N Engl J Med. 2007;357(18):1821–1828.

5. Weber F, Knopf H. Incidental findings in magnetic resonance imaging of the brains of healthy young men. J Neurol Sci. 2006;240(1-2):81–84.

6. Andree C, et al. Headache yesterday in Europe. J Headache Pain. 2014;15:33.

7. Morkve SH, et al. Surgical decompression of arachnoid cysts leads to improved quality of life: a prospective study. Neurosurgery. 2016;78(5):613–625.

8. Helland CA, Wester K. A population based study of intracranial arachnoid cysts: clinical and neuroimaging outcomes following surgical cyst decompression in adults. J Neurol Neurosurg Psychiatry. 2007;78(10):1129–1135.

9. Helland CA, Wester K. A population-based study of intracranial arachnoid cysts: clinical and neuroimaging outcomes following surgical cyst decompression in children. J Neurosurg. 2006;105(5 Suppl):385–390.

10. Couvreur T, et al. Endoscopic treatment of temporal arachnoid cysts in 34 patients. World Neurosurg. 2015;84.

11. Duz B, et al. Surgical management strategies of intracranial arachnoid cysts: a single institution experience of 75 cases. Turk Neurosurg. 2012;22(5):591–598.

12. Khan IS, et al. Surgical management of intracranial arachnoid cysts: clinical and radiological outcome. Turk Neurosurg. 2013;23(2):138–143.

13. Kimiwada T, et al. Shunt placement after cyst fenestration for middle cranial fossa arachnoid cysts in children. J Neurosurg Pediatr 2015;1–7.

14. Rabiei K, et al. Surgery for intracranial arachnoid cysts in children-a prospective long-term study. Childs Nervous System. 2016;32(7):1257–1263.

15. Wang C, et al. Individual surgical treatment of intracranial arachnoid cyst in pediatric patients. Neurol India. 2013;61(4):400–405.

16. Wang C, et al. Surgical treatment of intracranial arachnoid cyst in adult patients. Neurol India. 2013;61(1):60–64.

17. Helland CA, Wester K. Intracystic pressure in patients with temporal arachnoid cysts: a prospective study of preoperative complaints and postoperative outcome. J Neurol Neurosurg Psychiatry. 2007;78(6):620–623.

Chapter 2

Clinical Presentation, Symptoms, and Complaints

Dizziness/Vertigo

Camilla Tunes¹, Frederik K. Goplen¹,² and Knut Wester¹,²,    ¹Haukeland University Hospital, Bergen, Norway,    ²University of Bergen, Bergen, Norway

Abstract

Vestibular symptoms, such as dizziness, vertigo, and imbalance, have a major negative impact on the quality of life. Such complaints are common among patients with arachnoid cysts (ACs), but also in the general population; therefore, the occurrence of vestibular symptoms in AC patients may be incidental. In the relatively few studies on patients with symptomatic ACs that have been published, the prevalence of vestibular symptoms varies between 26% and 69.7%, in most studies in the range of 40%–50%. The dizziness in patients with posterior fossa cysts may be associated with objectively registered postural instability, unlike patients with temporal cysts, who as a group does not exhibit such unsteadiness. However, individual patients with a temporal AC may nevertheless show postural instability. A large proportion of patients with AC in the posterior and temporal fossae are relieved of such complaints or considerably improved after surgical cyst decompression.

Keywords

Arachnoid cyst; balance; dizziness; imbalance; vertigo; vestibular

Outline

Abbreviations 10

Recommendations—Level of Evidence 10

Level I 10

Level II 10

Introduction 10

Vestibular Symptoms and Findings in Patients With Arachnoid Cysts 12

Clinical Signs 12

Posterior Fossa Cysts 13

Middle Fossa Cysts 17

Discussion 18

Conclusion 19

References 19

Abbreviations

AC arachnoid cyst

CDP computerized dynamic posturography

CPA cerebellopontine angle

CT computerized tomography

DHI dizziness handicap inventory

EMG electromyography

SOT sensory organization test

VAS visual analogue scale

VEMP vestibular evoked myogenic potentials

VSS-SF vertigo symptoms scale - short form

Recommendations—Level of Evidence

Level I

There is no Level I evidence available for topics covered in this chapter.

Level II

There is Level II evidence that arachnoid cysts in the posterior and the temporal fossa cause subjective dizziness that is relieved by cyst decompression.

Introduction

Vestibular symptoms, such as dizziness, vertigo, and imbalance are common complaints among patients with arachnoid cysts (ACs). Prospective studies [1,2] have reported dizziness in 37%–70% of AC patients, while retrospective studies [3–5] report a frequency of 26%–46%. These symptoms have been shown to have a major negative impact on the quality of life in patients with arachnoid cysts [2] as well as in patients with vestibular disorders [6,7], see Chapter 16, Pre- and Postoperative Quality of Life in Arachnoid Cyst Patients.

However, it is important to realize that vestibular symptoms are nonspecific and common in the general population [8]. Since arachnoid cysts also are common [9–12], the occurrence of vestibular symptoms in these patients may be incidental. In a population-based study, people aged 70 years or above were examined for hitherto undiagnosed intracranial pathological conditions with computed tomography (CT) and interviews. The study concluded that the presence of an incidentally found AC did not influence the frequency of common symptoms, including dizziness [13]. A degree of caution may therefore be warranted before attributing vestibular symptoms to an AC.

In some patients, a solid case can be made for claiming that vestibular symptoms are caused by an arachnoid cyst. A cyst located in the cerebellopontine angle (CPA) may cause vestibular symptoms due to pressure on the vestibulocochlear nerve. In some of these cases an ipsilateral vestibular nerve deficit can be confirmed objectively. Several case reports document cranial nerve deficits in posterior fossa AC patients as well as their improvement after surgical decompression [14–17].

In other cases, the evidence for a causal relationship may be less obvious. When evaluating a patient with dizziness or unsteadiness, it is important to be aware of the fact that these are not always of vestibular origin. However, as a rule of thumb, the simultaneous occurrence of vertigo, unsteadiness, nausea, and nystagmus is a strong indicator of vestibular involvement. A simultaneous ipsilateral sensorineural hearing loss strongly suggests damage to the 8th cranial nerve or the inner ear. However, in spite of the close proximity of the vestibular and cochlear nerves within the internal auditory canal, these nerves are not always equally affected by lesions in the CPA. For example, there is only a weak correlation between vestibular and cochlear nerve function in patients with untreated vestibular schwannomas [18].

Less specific signs and symptoms may result from a mass effect of an AC on central vestibular structures. The most important central vestibular connections are the vestibular nuclei—located in the brainstem close to the floor of the fourth ventricle—and their projections to the cerebellum, particularly the vermis and the flocculonodular lobe. Certain areas of the temporal cortex are also activated by vestibular stimuli [19], and could be responsible for vestibular symptoms in temporal ACs. In these patients, indirect evidence for a causal relationship between the cyst and vestibular symptoms may be symptom severity, failure to find other causes after thorough neuro-otological assessment, and improvement after