Management of subdural hygromas associated with arachnoid cysts

Clinical article

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Object

Arachnoid cysts may occasionally be associated with subdural hygromas. The management of these concurrent findings is controversial.

Methods

The authors reviewed their experience with arachnoid cysts and identified 8 patients with intracranial arachnoid cysts and an associated subdural hygroma. The medical records and images for these patients were also examined.

Results

In total, 8 patients presented with concurrent subdural hygroma and arachnoid cyst. Of these 8 patients, 6 presented with headaches and 4 had nausea and vomiting. Six patients had a history of trauma. One patient was treated surgically at the time of initial presentation, and 7 patients were managed without surgery. All patients experienced complete resolution of their presenting signs and symptoms.

Conclusions

Subdural hygroma may lead to symptomatic presentation for otherwise asymptomatic arachnoid cysts. The natural course of cyst-associated subdural hygromas, even when symptomatic, is generally benign, and symptom resolution can be expected in most cases. The authors suggest that symptomatic hygroma is not an absolute indication for surgical treatment and that expectant management can result in good outcomes in many cases.

Abbreviations used in this paper:CN = cranial nerve; ICP = intracranial pressure.

Abstract

Object

Arachnoid cysts may occasionally be associated with subdural hygromas. The management of these concurrent findings is controversial.

Methods

The authors reviewed their experience with arachnoid cysts and identified 8 patients with intracranial arachnoid cysts and an associated subdural hygroma. The medical records and images for these patients were also examined.

Results

In total, 8 patients presented with concurrent subdural hygroma and arachnoid cyst. Of these 8 patients, 6 presented with headaches and 4 had nausea and vomiting. Six patients had a history of trauma. One patient was treated surgically at the time of initial presentation, and 7 patients were managed without surgery. All patients experienced complete resolution of their presenting signs and symptoms.

Conclusions

Subdural hygroma may lead to symptomatic presentation for otherwise asymptomatic arachnoid cysts. The natural course of cyst-associated subdural hygromas, even when symptomatic, is generally benign, and symptom resolution can be expected in most cases. The authors suggest that symptomatic hygroma is not an absolute indication for surgical treatment and that expectant management can result in good outcomes in many cases.

Increasing use of diagnostic intracranial imaging has led to more frequent diagnosis of arachnoid cysts.1,2,4,24,38,39,77,79,84 Although arachnoid cysts are occasionally symptomatic, most agree that a majority of arachnoid cysts are found incidentally.1,2,48,60,73 There are reports of cysts arising de novo,57,63,71 as well as cysts becoming larger or smaller over time,50,65,67 and even spontaneously resolving.19,35,67,74,80,82 We recently reported on the natural history of these lesions in children2 and adults1 and found a generally benign natural history.

Many surgeons have suggested that clearly symptomatic arachnoid cysts should be treated.7,18,21,25,27,28,37,44,46,48,50,55,85 In some cases, previously asymptomatic arachnoid cysts may rupture, causing a symptomatic hygroma in the subdural space.3,6,9,11,12,15,18,23,26,28,42,58,62,68,82 Most prior reports have advocated surgical treatment for arachnoid cyst–associated subdural hygromas.3,7,8,20,28,29,59,72 We have observed that patients with a symptomatic subdural hygroma associated with an arachnoid cyst will frequently experience complete and lasting spontaneous resolution of their neurological symptoms if managed without surgery. We report our recent experience with managing arachnoid cyst–associated subdural hygromas without surgery and suggest that the often benign natural history of this condition should be considered when making treatment decisions.

Methods

After obtaining approval from the University of Michigan Institutional Review Board, we reviewed the medical records and imaging results of children who presented to the pediatric neurosurgical service at the University of Michigan between January 2009 (the date that we began to prospectively collect clinical information on patients with arachnoid cysts) and February 2012 to identify all patients who presented for an evaluation of an arachnoid cyst with associated hygroma. All patients underwent brain MRI performed using either a 1.5-T or 3-T imaging unit. All patients who had a cyst-associated hygroma during this interval were included. During this time period, 1 patient with an associated subdural hematoma was excluded. We found patients who presented with arachnoid cysts and hygromas that were managed without surgery at the University of Michigan (Cases 1–6). To these we added a single case that was managed without surgery at Nationwide Children's Hospital (Case 7). Finally, we found 1 patient with an arachnoid cyst–associated hygroma who was surgically treated at our institution during this time period (Case 8). For each of these patients, we collected information including age, sex, presenting symptoms, trauma history, surgical history, and clinical course. The images were examined in every case to confirm the diagnosis of arachnoid cyst and subdural hygroma as well as to assess for any changes over time. Patients with subdural hematomas were not included in this analysis.

Summary of Cases

Case 1

A 10-year-old boy presented 3 weeks after a minor head injury. He experienced mild headaches from the time of injury, but at 3 weeks after injury, he began to experience worsening headaches. Computed tomography scanning showed a large left middle fossa arachnoid cyst (Fig. 1). Findings during the neurological examination were normal. After a discussion with the child and his parents, we decided to manage the hygroma without surgery. In the days after this decision, the patient's symptoms initially worsened. He began to have nausea and vomiting and developed diplopia. He was seen by an ophthalmologist who documented bilateral papilledema and a left cranial nerve (CN) VI palsy. A new MR image showed that the subdural collection had expanded. Initial plans were made for surgical treatment within several days, but the diplopia markedly improved within 2 days, and plans for surgery were cancelled. Two weeks later, all symptoms including the diplopia had completely resolved and the papilledema had improved. Magnetic resonance imaging confirmed resolution of the subdural hygroma and persistence of the arachnoid cyst.

Fig. 1.
Fig. 1.

Case 1. Head CT scans obtained 3 weeks after minor head injury showing a left middle fossa arachnoid cyst with a subtle associated hygroma (A and B). The hygroma is larger on MR images obtained 2 months later (C and D), but has resolved on the most recent MR images (E and F).

Case 2

A 12-year-old girl presented to the emergency department 2.5 weeks after a minor head injury that occurred during a soccer game. She had immediate onset of a headache after the injury. Her headache progressively worsened over the next several days, and she began to experience nausea and vomiting, but she had no visual complaints. A right middle fossa arachnoid cyst with associated hygroma was found on MRI. Four weeks later, her headaches were much better and the hygroma was smaller. Three months after the injury, the headaches had resolved and the hygroma had disappeared. The arachnoid cyst appeared unchanged.

Case 3

A 16-year-old boy began to experience headaches 1 day after sustaining a minor head injury during a football game. The headaches lasted for approximately 2 weeks and then resolved. At the time of his presentation to the neurosurgy clinic, he was asymptomatic and had normal findings on examination. Magnetic resonance imaging demonstrated a right middle fossa arachnoid cyst and bilateral subdural hygromas (Fig. 2). No treatment was recommended. Follow-up imaging performed 3 months after the injury showed a decrease in the size of the hygroma and the arachnoid cyst. Further decrease in size was noted at the 1-year follow-up.

Fig. 2.
Fig. 2.

Case 3. T2-weighted MR images obtained 2 weeks after minor head injury showing a right middle fossa arachnoid cyst with an associated subdural hygroma (A and B). Three months later, both the cyst and hygroma are smaller (C and D). The most recent scan shows continued resolution of the arachnoid cyst 1 year after injury (E and F).

Case 4

An 8-year-old boy presented to his primary care physician with a gradually worsening headache 2 weeks after a minor head injury. He had vomited once several days earlier but had no other complaints. His neurological examination was normal. Three weeks later, he presented to the emergency department with a headache and transient subjective diplopia that resolved within 20 minutes. Findings during neurological examination remained normal. Brain MRI demonstrated a right middle cranial fossa arachnoid cyst and a thin subdural hygroma over the cerebral convexities bilaterally. During the following week, the patient had 4 episodes of vomiting and complained of a headache on several occasions. Repeat MRI was performed 3 weeks later because of persistent headaches and showed a subtle interval increase in the hygroma with interval increase in the mass effect on the right cerebral hemisphere. Two months later the patient was asymptomatic, and MRI showed slight reduction in size of the hygroma. The hygroma had completely resolved on MRI performed 7 months later. The arachnoid cyst was unchanged.

Case 5

A 12-month-old girl was found to have a rapid increase in head circumference on routine screening. Head CT showed a left middle fossa arachnoid cyst and an associated subdural hygroma with mass effect on the ipsilateral hemisphere. Of note, the patient had an unwitnessed fall from her crib 1 month earlier. The patient was neurologically normal after the fall, and the parents did not seek medical care. Since the patient was asymptomatic, surgical treatment was deferred. Magnetic resonance images obtained 1 month, 4 months, and 18 months later confirmed gradual resolution of the hygroma, although the cyst remained unchanged. The rate of head growth slowed, and the child remained neurologically and developmentally normal.

Case 6

A 13-month-old boy presented with a 6-week history of vomiting and a rapid increase in head circumference. Cranial ultrasonography demonstrated a left middle fossa arachnoid cyst and bilateral convexity subdural fluid collections; MRI confirmed these findings. The subdural collections were asymmetric, and minimal sulcal effacement was noted on the side ipsilateral to the larger collection. One month later, the patient was asymptomatic. A follow-up imaging study performed 3 months later showed that the bilateral subdural spaces were much smaller. Ten months after the initial presentation, follow-up imaging showed a further decrease in size of the subdural fluid spaces and a small decrease in the size of the arachnoid cyst. The patient is now neurologically and developmentally normal 12 months after the initial evaluation.

Case 7

A 10-year-old boy sustained a minor head injury without loss of consciousness. He developed headache with photophobia, nausea, and vomiting 1 day after the injury, and these symptoms gradually worsened. Computed tomography scanning performed 2 days after the injury demonstrated a right middle fossa arachnoid cyst. One week later, MRI demonstrated bilateral subdural hygromas in addition to the arachnoid cyst. At the time of his first neurosurgical evaluation 4 weeks after injury, the patient's symptoms had completely resolved. Repeat brain MRI performed at that time demonstrated a decrease in the subdural hygroma on the left, but a significant increase on the right (Fig. 3). As he was clinically well, the patient was managed without surgery. He remained neurologically intact over a 12-month follow-up period. Seven months after his first visit, MRI demonstrated a decrease in size of both the hygroma and the arachnoid cyst. Three months later, a further decrease in size of both the hygroma and cyst was again noted.

Fig. 3.
Fig. 3.

Case 7. T2-weighted MR images obtained 2 weeks after minor head injury (A and B). The right-sided hygroma is larger on scans obtained 2 weeks later (C) and 3 months later (D). Both the cyst and hygroma are significantly smaller on the MR images 1 year after injury (E and F).

Case 8

A 7-year-old boy presented with a 4-week history of headaches but without other symptoms. There was no known history of trauma. Magnetic resonance imaging showed a right middle fossa arachnoid cyst with an associated subdural hygroma. An ophthalmologist found bilateral papilledema. The patient was treated with a craniotomy for cyst fenestration. Postoperatively, the headaches completely resolved. However, routine follow-up MRI performed 6 months postoperatively demonstrated asymptomatic but significant enlargement of the cyst, and a cystoperitoneal shunt was placed. After this, the hygroma resolved and the cyst became progressively smaller on subsequent follow-up scans at 6-month, 1-year, and 2-year intervals following shunt placement. The patient remains asymptomatic 5 years postoperatively.

Discussion

Posttraumatic subdural hygromas are thought to arise from a tear in the arachnoid membrane resulting in a one-way valve mechanism that leads to the accumulation of CSF under abnormally elevated pressure. This theory, first articulated in 1924 by Naffziger,54 has remained the best explanation for the phenomenon of the symptomatic hygroma. In some cases, subdural hygromas are found in patients with arachnoid cysts. Cyst-associated hygromas may form when the outer cyst membrane tears, either spontaneously or as a result of trauma or surgical manipulation.15,52,53,81 Some have speculated that a change in local intracranial pressure (ICP) as a result of a Valsalva maneuver may also lead to cyst rupture with hygroma, although unrecognized or unrecorded trauma may also explain some of these cases.9,15,19,42 A tear in the cyst lining allowing communication between an arachnoid cyst and an associated subdural hygroma has been documented intraoperatively on at least 4 occasions.9,15,28,83

Hygromas undoubtedly result in elevated ICP in many cases. Evidence for this is found in the common symptoms that are seen with hygromas, as well as the physical findings that are sometimes seen, such as papilledema and even transient CN VI palsy.41,61 The pattern of presentation is remarkably consistent for these patients (Tables 1 and 2). Symptoms usually include headache, nausea, vomiting, and rarely diplopia from CN VI palsy. Physical findings are usually limited to papilledema. Most reported cases have a history of minor trauma without loss of consciousness. Symptoms usually become increasingly severe for days or weeks after onset, but they eventually resolve.

TABLE 1:

Reported cases of arachnoid cyst associated with subdural hygroma treated without surgery*

Authors & YearAge (yrs), SexCyst LocationTrauma HistoryTime Interval, Injury to PresentationInterval GrowthHANausea &/or VomitingPapilledemaDiplopiaTreatmentClinical OutcomeCyst Imaging Outcome
Choong & Lee, 1998 present series9, Flt MFno2 mosnoyesyesyesnoacetazolamidegoodunchanged
 Case 110, Mlt MFyes (minor)3 wksyesyesyesyesyesnogoodunchanged
 Case 212, Frt MFyes (minor)2.5 wksnoyesyesnononogoodunchanged
 Case 316, Mrt MFyes (minor)2 wksnoyesnonononogoodimproved
 Case 48, Mrt MFyes (minor)2 wksyesyesyesyesyesyesgoodunchanged
 Case 51, Flt MFyes (minor)1 monounknonononogoodunchanged
 Case 61, Mlt MFno6 wksnounkyesnononogoodimproved
 Case 710, Mrt MFyes (minor)2 wksyesyesyesnononogoodimproved
Mori et al., 199513, Mlt MFyesunkunkunkunkunkunknogoodimproved
Parsch et al., 199718, unklt MFyesunknononounknonogoodunk
Rakier & Feinsod, 19958, Frt MFno1 daynotransientnonononogoodresolved
Yamanouchi et al., 19869, Mlt MFyes (w/ LOC)5 daysyesyesyesnononogoodresolved

* HA = headache; LOC = loss of consciousness; MF = middle fossa; unk = unkown.

TABLE 2:

Reported cases of arachnoid cysts associated with subdural hygroma treated with surgery*

Authors & YearAge (yrs), SexCyst LocationTrauma HistoryTime Interval, Injury to PresentationInterval GrowthHANausea &/or VomitingPapilledemaDiplopiaTreatmentClinical OutcomeCyst Imaging Outcome
Albuquerque & Giannotta, 19976, Mlt MF, QCyes (minor)1 daynoyesyesunknoCCF, SD draingood (w/ SD shunt)unk
25, Mbilat MFyes (minor)1 daynounkunkunkunkSD draingoodunk
9, unkMFyesunknoyesyesunkunkSD draingoodunk
25, unkMFyesunknoyesyesunkunkSD shuntgoodunk
10, unklt MFnounknoyesyesunkunkSD shuntgoodunk
Bristol et al., 200717, Mrt MFyes (brief LOC)3 daysnoyesnounkunkCCFgoodunk
Cakir et al., 20049, Mrt MFnounknoyesyesnonobur hole & draingoodimproved
Cayli, 200012, Flt MFno3 wksnoyesyesyesnoCCFgoodimproved
Cullis & Gilroy, 198311, Mlt MFno (swimming)1 monoyesyesyesnoCCFunkunk
Dharmarajan et al., 19889, Munkyes (minor)1 monoyesyesunkunkCP shuntunkunk
Donaldson et al., 200014, Mlt MFyes (minor)4 wksnoyesyesyesnoCCFgoodunk
5, Mrt MFyes (minor)10 daysnoyesyesyesnoCCF2nd craniotomy 2 mos later; goodunk
Ergün et al., 199714, Mrt MFno20 daysnoyesyesyesnoCCFgoodimproved
Gelabert-González et al., 200213, Mlt MFyes (minor)4 wksnoyesnononoCCFgoodimproved
12, Mlt MFyes (minor)unkyesyesnononoCCFgoodimproved
6, Mlt MFyes (minor)1 monoyesyesunknoSD drainreq'd SD shunt, then OKunchanged
Goswami et al., 20088, Mrt MFyes (minor)1 wknoyesnounknoCCFgoodunk
Gupta et al., 200422, Mlt MFyes (minor)3 daysunkyesyesunknoacetazolamiderepeat drainage; unkunk
Herman & Siegel, 20100, unkretrocerebellarunkunknounknononoSD shuntgoodunk
Klein et al., 200614, Mrt MFyes (minor)2 wksyesyesyesunkyesSD drainsnew CN palsy & SD shunt req'dunk
Kulali & von Wild, 198915, Mrt MFno (dancing)3 wksnoyesyesyesnoCCFgoodunk
6, Mrt MFyes (minor)4 wksnoyesyesunknoCCFreq'd SD shunt, then OKimproved
Longatti et al., 20057, Mrt MFyes1 moyesyesyesyesyessteroid & acetazolamidegoodunchanged
present series (Case 8)7, Mrt MFno4 wksnoyesnoyesnoCCFCP shuntenlarged then improved
Offiah et al., 20068, Mbilat MFyes (minor)? wksnoyesyesnonobur holesrecurrent symptoms, pseudomeningocele, SD shuntenlarged
Parsch et al., 19975, unklt MFyesunknoyesyesunkunkSD drainrevisions then shunt; infectionunk
12, unkrt MFyesunknoyesyesunkunkCCF & drainsgoodunk
18, unkrt MFyesunknounkunkunkunkbur holespseudomeningocele; no shuntunk
Poirrier et al., 200415, Mrt MFno5 daysnoyesyesunkunkCCF & drainshunt, then goodunchanged
Rajesh et al., 201215, Mlt MFyes (minor)20 daysnoyesyesyesyesCCFpseudomeningocele & temporary drainunk
Sener, 199712, Mlt MFnoacute onsetnoyesunkunkunkCCFunkunk
Vigil et al., 199816, Mlt MFyes (minor)3 wksyesyesyesyesyesbur holes, then SD drains, then endoscopic fenestrationgoodunk

* CCF = craniotomy for cyst fenestration; CP = cystoperitoneal; QC = quadrigeminal cistern; req'd = required; SD = subdural.

Some authors have suggested that surgical treatment of subdural hygromas associated with arachnoid cysts is always or almost always necessary,3,7,8,28,29,59,72 with some going so far as to call nonsurgical management inappropriate.20 Others have even suggested that hygromas, since they have symptoms of elevated ICP, should be considered potentially life threatening.3 Although this is no doubt theoretically or even actually possible, we have never encountered a report of a fatality or permanent neurological deficit resulting from nonsurgical management of an arachnoid cyst–associated hygroma. The case series described above identifies the possibility of a benign natural history for arachnoid cyst–associated subdural hygroma. Every patient in this series who was managed nonoperatively experienced a complete symptomatic resolution. Therefore, we suggest that the decision to surgically treat symptomatic hygromas associated with arachnoid cysts should be made carefully and only after the generally benign natural history of this condition is considered. Half of the patients in this series with cyst-associated hygroma had objective findings strongly correlated with elevated ICP including CN VI palsy, papilledema, and progressive macrocephaly, yet all these patients had spontaneous resolution of these physical findings; therefore, symptoms of elevated ICP are not an absolute indication for surgical treatment in our opinion. If headaches and vomiting are added to the list of ICP-related symptoms, then in 7 of our cases, symptoms of elevated ICP resolved without treatment. Furthermore, the one patient who was treated surgically had a very large arachnoid cyst; this was not typical of our recent experience. Because of what appears to be a high potential for spontaneous resolution, in patients presenting with new-onset symptoms of elevated ICP and an arachnoid cyst, the possible presence of an associated hygroma should be carefully investigated before pursuing any surgical cyst treatment. If a hygroma is found in a patient with new-onset symptoms, we believe that this should suggest that an initial decision to manage without surgery is likely to result in a good outcome with symptom resolution in many cases. Close clinical follow-up is required for symptomatic patients who are managed without surgery. We would still prefer surgical treatment as an initial therapy for patients with severe symptoms or an especially concerning neurological examination. Furthermore, surgical treatment is indicated for those patients whose condition is refractory to initial conservative management. In our practice, we would generally attempt to treat with surgical fenestration and would reserve shunt placement for those with treatment failures after fenestration.

The suggestion that arachnoid cysts should be treated if they demonstrate evidence of local mass effect on imaging26,30,33,36,37 is potentially problematic in the context of subdural hygroma. Any moderately sized hygroma will have the appearance of mass effect on imaging. The appearance of local mass effect, therefore, is too inclusive to be used as a reliable criterion for selecting patients who require treatment. Furthermore, most asymptomatic arachnoid cysts even in the absence of hygroma will produce the appearance of local mass effect on adjacent tissues.

Including all reported cases of arachnoid cyst with associated subdural hygroma in which the treatment and outcome has been specified, there are 28 reported cases that have been surgically treated by means other than initial shunt placement (Table 2). Of these, 9 patients ultimately underwent shunt placement as a secondary procedure. Unfortunately, shunt placement carries the additional risk of shunt dependency and overdrainage.40,49,69 We believe that subdural shunt placement, a treatment that has been sometimes advocated for these lesions,3,28 will usually result in the unintended effect of maintaining a fistula though this torn lining, thus leading to a persistent tear and shunt dependency.33,85

Acetazolamide has occasionally been used to treat symptomatic hygromas associated with arachnoid cysts. Of the reported cases in which this treatment was tried, 2 patients had symptom resolution without surgery11,45 and 1 patient went on to have surgical decompression of the hygroma.31 In addition, Tamburrini et al.72 reported on 2 patients who had a short trial of acetazolamide for symptomatic postoperative hygromas after arachnoid cyst fenestration, but this treatment did not improve symptoms in either case. Given the tendency for symptoms to resolve over time in many cases, it is impossible to make any claims about the efficacy of acetazolamide treatment for this condition based on the existing literature.

Hygroma resolution with the return of prior arachnoid cyst dimensions may result from healing of the tear in the outer arachnoid cyst lining.11 Persistent tears in the lining might lead to cyst resolution in rare cases.5,19 Supporting this theory, the development of a subdural hygroma has occasionally been associated with concurrent “spontaneous” cyst size reduction or resolution. Including our own 3 cases (Cases 3, 6, and 7), this phenomenon has now been reported 6 times.5,35,82 Furthermore, in a recent review of all reported cases of documented “spontaneous” arachnoid cyst resolution, Thomas et al. found that 6 of 19 cases had a recent history of head injury, suggesting that an unrecognized tear in the cyst lining may explain at least some of these cases.67,74 Spontaneous cyst resolution has also been documented in patients with no history of trauma or subdural hygroma,35,51,62,80,82 although it is difficult to exclude minor trauma in this group of children. We may also speculate that rupture not only of the outer cyst lining in the subdural space, but also of the inner lining adjacent to the basal cisterns, may be especially likely to lead to cyst resolution.19 There are 2 previously reported cases of traumatic cyst rupture with resulting dilation of the basal cisterns.3

In numerous reports, surgeons have encountered fluid under pressure while treating these lesions surgically.3,9,28 These pressure elevations sometimes persist for long durations postoperatively, occasionally resulting in permanent shunt placement, even if that was not the original surgical plan.3,84,85 The new onset of subdural hygroma is a recognized side effect of arachnoid cyst fenestration. In reported series, surgical fenestration of arachnoid cysts has resulted in iatrogenic postoperative subdural hygroma in approximately 4% to 29% of cases.11,13,18,21,22,25,30,36,44,48,60,66,69,70,72,84 The incidence of asymptomatic subdural collections following surgical fenestration may be even higher.66 As with idiopathic or posttraumatic hygromas, these postoperative hygromas may cause symptoms of elevated ICP,72 leading Maixner et al.47 to term this phenomenon “pseudotumor syndrome following surgery for arachnoid cysts.” The higher than expected rate of postoperative pseudomeningoceles84 and CSF leaks84 after fenestration probably results from a transient ICP elevation after cyst fenestration. The tendency for postoperative subdural hygromas to become symptomatic days or weeks after the initial cyst fenestration procedure may be analogous to the posttraumatic variety presenting days or weeks after the traumatic event.72 In many previously reported cases, the development of a new symptomatic hygroma after cyst fenestration was treated with further surgery including permanent shunting of the subdural space.13,18,25,30,60,66,70,72,84

If the presenting symptoms and imaging appearance are similar between idiopathic, posttraumatic, and postsurgical cyst-associated hygromas, it is possible that postoperative cyst-associated hygromas are likely to share a common natural history as well. In our own practice, we have treated 2 patients for arachnoid cysts in the last 6 years who have developed new symptomatic subdural hygromas after cyst fenestration. In both cases, the patients initially did well after surgery and were dismissed from the hospital in good condition. They then returned with symptoms of elevated ICP including persistent nausea and vomiting in the weeks after surgery. In both cases, no further treatment other than an admission for intravenous fluid resuscitation was needed, and the symptoms and scans improved over the course of the following month. Based on our own experience with postoperative hygromas, as well as the often benign natural course of idiopathic and posttraumatic cyst-associated hygromas, it has become our own practice to initially recommend no further surgical treatment for postoperative subdural hygromas after cyst fenestration, even when they are symptomatic. As with spontaneous or posttraumatic hygromas, we only recommend surgical treatment in cases that are refractory to conservative measures.

The prevalence of hygroma in patients with arachnoid cysts is not known and, due to detection bias, this case series of patients who presented with neurological symptoms is not able to shed light on that issue. Patients with a subdural hygroma are more likely to be symptomatic and, therefore, more likely to come to medical attention. In prior reports, we analyzed all patients undergoing MRI rather than those who presented for neurosurgical attention.1,2 We would expect that analysis of a general imaging database would have less detection bias for subdural hygroma compared with a clinical case series. In our prior analysis of 309 arachnoid cysts in children who were identified using an imaging database that included consecutive patients who underwent MRI of the brain for any reason at our institution between January 1997 and June 2008, we found only 2 children who presented with a hygroma.2 In a subsequent analysis of 661 adult patients with arachnoid cysts using our imaging database, we found 1 symptomatic patient and 1 asymptomatic patient who presented with both hygroma and an arachnoid cyst on initial imaging.1 Furthermore, in prior reports, we observed 111 children with arachnoid cysts for a mean duration of 3.5 years and 213 adults for a mean duration of 3.8 years and found no patient in those groups who developed hygroma during the follow-up intervals.1,2 We conclude that hygroma appears to be a rare complication of an untreated arachnoid cyst, but the exact prevalence cannot be determined based on existing data.

There are several limitations to our report. We did not include patients with arachnoid cysts and associated subdural hematomas, and we do not believe that this case series should be applied to that very different patient population. In our review of the literature, it is possible that some patients in prior reports who were diagnosed as having a cyst with associated hematoma, in fact, had a hygroma. We made an effort to exclude patients with subdural hemorrhage rather than hygroma.43,68,76 This distinction is sometimes difficult when interpreting early reports, since there may still be some confusion regarding the classification of subdural collections.75 There are intriguing reports from the era preceding modern CT and MRI that describe patients with delayed onset of headaches and nausea days after a minor head injury who were later discovered to harbor arachnoid cysts. Unfortunately, the anatomical description is not sufficient to determine if hygromas were present as a determining factor in these cases.43,64 Similarly, very early reports of arachnoid cysts occasionally considered the cyst itself as a “hygroma in the subdural space.”10,14,16,32,64 Finally, our own case series represents the recent experience at a single center and may have been influenced by referral bias or even by chance. These limitations should be considered in any interpretation of our results.

Conclusions

Subdural hygroma may lead to symptomatic presentation for otherwise asymptomatic arachnoid cysts. The natural course of cyst-associated subdural hygromas, even when symptomatic, is generally benign, and symptom resolution can be expected in most cases. We suggest that symptomatic hygroma is not an absolute indication for surgical treatment and that expectant management can result in good outcomes in many cases.

Acknowledgement

The authors would like to thank Holly Wagner for providing editorial assistance.

Disclosure

The authors report no conflict of interest concerning the materials or methods used in this study or the findings specified in this paper.

Author contributions to the study and manuscript preparation include the following. Conception and design: Maher, Jackson. Acquisition of data: Maher, Jackson, Al-Holou, Garton, Trobe. Analysis and interpretation: Maher, Jackson, Garton. Drafting the article: Maher, Jackson, Garton, Al-Holou, Trobe, Muraszko. Critically revising: all authors. Reviewed submitted: all authors. Approved final version: Maher. Study supervision: Maher.

References

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Article Information

Address correspondence to: Cormac O. Maher, M.D., Department of Neurosurgery, University of Michigan, 1500 E. Medical Center Dr., Room 3552 Taubman Center, Ann Arbor, MI 48109. email: cmaher@med.umich.edu.

Please include this information when citing this paper: published online September 6, 2013; DOI: 10.3171/2013.8.PEDS13206.

© AANS, except where prohibited by US copyright law.

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Figures

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    Case 1. Head CT scans obtained 3 weeks after minor head injury showing a left middle fossa arachnoid cyst with a subtle associated hygroma (A and B). The hygroma is larger on MR images obtained 2 months later (C and D), but has resolved on the most recent MR images (E and F).

  • View in gallery

    Case 3. T2-weighted MR images obtained 2 weeks after minor head injury showing a right middle fossa arachnoid cyst with an associated subdural hygroma (A and B). Three months later, both the cyst and hygroma are smaller (C and D). The most recent scan shows continued resolution of the arachnoid cyst 1 year after injury (E and F).

  • View in gallery

    Case 7. T2-weighted MR images obtained 2 weeks after minor head injury (A and B). The right-sided hygroma is larger on scans obtained 2 weeks later (C) and 3 months later (D). Both the cyst and hygroma are significantly smaller on the MR images 1 year after injury (E and F).

References

1

Al-Holou WNTerman SKilburg CGarton HJMuraszko KMMaher CO: Prevalence and natural history of arachnoid cysts in adults. Clinical article. J Neurosurg 118:2222312013

2

Al-Holou WNYew AYBoomsaad ZEGarton HJMuraszko KMMaher CO: Prevalence and natural history of arachnoid cysts in children. Clinical article. J Neurosurg Pediatr 5:5785852010

3

Albuquerque FCGiannotta SL: Arachnoid cyst rupture producing subdural hygroma and intracranial hypertension: case reports. Neurosurgery 41:9519561997

4

Banna M: Arachnoid cysts on computed tomography. AJR Am J Roentgenol 127:9799821976

5

Beltramello AMazza C: Spontaneous disappearance of a large middle fossa arachnoid cyst. Surg Neurol 24:1811831985

6

Bilginer BOnal MBOguz KKAkalan N: Arachnoid cyst associated with subdural hematoma: report of three cases and review of the literature. Childs Nerv Syst 25:1191242009

7

Bristol REAlbuquerque FCMcDougall CSpetzler RF: Arachnoid cysts: spontaneous resolution distinct from traumatic rupture. Case report. Neurosurg Focus 22:2E22007

8

Cakir EKayhankuzeyli Sayin OCPeksoylu BKaraarslan G: Arachnoid cyst rupture with subdural hygroma: case report and literature review. Neurocirugia (Astur) 15:72752004

9

Cayli SR: Arachnoid cyst with spontaneous rupture into the subdural space. Br J Neurosurg 14:5685702000

10

Childe AE: Localized thinning and enlargement of the cranium, with special reference to the middle fossa. Am J Roentgenol Radium Ther Nucl Med 70:1221953

11

Choong CTLee SH: Subdural hygroma in association with middle fossa arachnoid cyst: acetazolamide therapy. Brain Dev 20:3193221998

12

Choux MRaybaud CPinsard NHassoun JGambarelli D: Intracranial supratentorial cysts in children excluding tumor and parasitic cysts. Childs Brain 4:15321978

13

Cinalli GPeretta PSpennato PSavarese LVarone AVedova P: Neuroendoscopic management of interhemispheric cysts in children. J Neurosurg 105:3 Suppl1942022006

14

Cohen I: Chronic subdural accumulations of cerebrospinal fluid after cranial trauma. Arch Neurol Psychiatry 18:7097231927

15

Cullis PAGilroy J: Arachnoid cyst with rupture into the subdural space. J Neurol Neurosurg Psychiatry 46:4544561983

16

Dandy WE: Treatment of an unusual subdural hydroma (external hydrocephalus). Arch Surg 52:4214281946

17

Dharmarajan SKalyanaraman SSivakumar S: Rupture of a sylvian arachnoid cyst producing subdural hygroma. Neurol India 36:2452471988

18

Di Rocco C: Sylvian fissure arachnoid cysts: we do operate on them but should it be done?. Childs Nerv Syst 26:1731752010

19

Dodd RLBarnes PDHuhn SL: Spontaneous resolution of a prepontine arachnoid cyst. Case report and review of the literature. Pediatr Neurosurg 37:1521572002

20

Donaldson JWEdwards-Brown MLuerssen TG: Arachnoid cyst rupture with concurrent subdural hygroma. Pediatr Neurosurg 32:1371392000

21

El-Ghandour NMF: Endoscopic treatment of middle cranial fossa arachnoid cysts in children. Clinical article. J Neurosurg Pediatr 9:2312382012

22

Elhammady MSBhatia SRagheb J: Endoscopic fenestration of middle fossa arachnoid cysts: a technical description and case series. Pediatr Neurosurg 43:2092152007

23

Ergün ROkten AIBeşkonakli EAnasiz HErgüngör FTaşkin Y: Unusual complication of arachnoid cyst: spontaneous rupture into the subdural space. Acta Neurochir (Wien) 139:6926941997

24

Eskandary HSabba MKhajehpour FEskandari M: Incidental findings in brain computed tomography scans of 3000 head trauma patients. Surg Neurol 63:5505532005

25

Fewel MELevy MLMcComb JG: Surgical treatment of 95 children with 102 intracranial arachnoid cysts. Pediatr Neurosurg 25:1651731996

26

Galassi EPiazza GGaist GFrank F: Arachnoid cysts of the middle cranial fossa: a clinical and radiological study of 25 cases treated surgically. Surg Neurol 14:2112191980

27

Gangemi MSeneca VColella GCioffi VImperato AMaiuri F: Endoscopy versus microsurgical cyst excision and shunting for treating intracranial arachnoid cysts. Clinical article. J Neurosurg Pediatr 8:1581642011

28

Gelabert-González MFernández-Villa JCutrín-Prieto JGarcìa Allut AMartínez-Rumbo R: Arachnoid cyst rupture with subdural hygroma: report of three cases and literature review. Childs Nerv Syst 18:6096132002

29

Goswami PMedhi NSarma PKSarmah BJ: Case report: Middle cranial fossa arachnoid cyst in association with subdural hygroma. Indian J Radiol Imaging 18:2222232008

30

Gui SBWang XSZong XYLi CZLi BZhang YZ: Assessment of endoscopic treatment for middle cranial fossa arachnoid cysts. Childs Nerv Syst 27:112111282011

31

Gupta RVaishya SMehta VS: Arachnoid cyst presenting as subdural hygroma. J Clin Neurosci 11:3173182004

32

Hardman J: Asymmetry of the skull in relation to subdural collections of fluid. Br J Radiol 12:4554611939

33

Harsh GR IVEdwards MSWilson CB: Intracranial arachnoid cysts in children. J Neurosurg 64:8358421986

34

Herman TESiegel MJ: Autosomal dominant polycystic disease with associated arachnoid cysts and subdural cystic hygroma requiring shunting. J Perinatol 30:5665682010

35

Inoue TMatsushima TTashima SFukui MHasuo K: Spontaneous disappearance of a middle fossa arachnoid cyst associated with subdural hematoma. Surg Neurol 28:4474501987

36

Johnson RDChapman SBojanic S: Endoscopic fenestration of middle cranial fossa arachnoid cysts: does size matter?. J Clin Neurosci 18:6076122011

37

Kang JKLee KSLee IWJeun SSSon BCJung CK: Shunt-independent surgical treatment of middle cranial fossa arachnoid cysts in children. Childs Nerv Syst 16:1111162000

38

Katzman GLDagher APPatronas NJ: Incidental findings on brain magnetic resonance imaging from 1000 asymptomatic volunteers. JAMA 282:36391999

39

Kim BSIlles JKaplan RTReiss AAtlas SW: Incidental findings on pediatric MR images of the brain. AJNR Am J Neuroradiol 23:167416772002

40

Kim SKCho BKChung YNKim HSWang KC: Shunt dependency in shunted arachnoid cyst: a reason to avoid shunting. Pediatr Neurosurg 37:1781852002

41

Klein ABalmer BBrehmer UHuisman TABoltshauser E: Facial nerve palsy—an unusual complication after evacuation of a subdural haematoma or hygroma in children. Childs Nerv Syst 22:5625662006

42

Kulali Avon Wild K: Post-traumatic subdural hygroma as a complication of arachnoid cysts of the middle fossa. Neurosurg Rev 12:Suppl 15085131989

43

Lesoin FDhellemmes PRousseaux MJomin M: Arachnoid cysts and head injury. Acta Neurochir (Wien) 69:43511983

44

Levy MLWang MAryan HEYoo KMeltzer H: Microsurgical keyhole approach for middle fossa arachnoid cyst fenestration. Neurosurgery 53:113811452003

45

Longatti PMarton EBilleci D: Acetazolamide and corticosteroid therapy in complicated arachnoid cyst. Childs Nerv Syst 21:106110642005

46

Maher COGoumnerova L: The effectiveness of ventriculocystocisternostomy for suprasellar arachnoid cysts. Clinical article. J Neurosurg Pediatr 7:64722011

47

Maixner VJBesser MJohnston IH: Pseudotumor syndrome in treated arachnoid cysts. Childs Nerv Syst 8:2072101992

48

Marin-Sanabria EAYamamoto HNagashima TKohmura E: Evaluation of the management of arachnoid cyst of the posterior fossa in pediatric population: experience over 27 years. Childs Nerv Syst 23:5355422007

49

Martínez-Lage JFRuíz-Espejo AMAlmagro MJAlfaro RFelipe-Murcia MLópez-Guerrero AL: CSF overdrainage in shunted intracranial arachnoid cysts: a series and review. Childs Nerv Syst 25:106110692009

50

McDonald PJRutka JT: Middle cranial fossa arachnoid cysts that come and go. Report of two cases and review of the literature. Pediatr Neurosurg 26:48521997

51

Mokri BHouser OWDinapoli RP: Spontaneous resolution of arachnoid cysts. J Neuroimaging 4:1651681994

52

Mori KYamamoto THorinaka NMaeda M: Arachnoid cyst is a risk factor for chronic subdural hematoma in juveniles: twelve cases of chronic subdural hematoma associated with arachnoid cyst. J Neurotrauma 19:101710272002

53

Mori TFujimoto MSakae KSakakibara TShin HYamaki T: Disappearance of arachnoid cysts after head injury. Neurosurgery 36:9389421995

54

Naffziger HC: Subdural fluid accumulations following head injury. JAMA 82:175117521924

55

Oberbauer RWHaase JPucher R: Arachnoid cysts in children: a European co-operative study. Childs Nerv Syst 8:2812861992

56

Offiah CSt Clair Forbes WThorne J: Non-haemorrhagic subdural collection complicating rupture of a middle cranial fossa arachnoid cyst. Br J Radiol 79:79822006

57

Okumura YSakaki THirabayashi H: Middle cranial fossa arachnoid cyst developing in infancy. Case report. J Neurosurg 82:107510771995

58

Parsch CSKrauss JHofmann EMeixensberger JRoosen K: Arachnoid cysts associated with subdural hematomas and hygromas: analysis of 16 cases, long-term follow-up, and review of the literature. Neurosurgery 40:4834901997

59

Poirrier ALNgosso-Tetanye IMouchamps MMisson JP: Spontaneous arachnoid cyst rupture in a previously asymptomatic child: a case report. Eur J Paediatr Neurol 8:2472512004

60

Pradilla GJallo G: Arachnoid cysts: case series and review of the literature. Neurosurg Focus 22:2E72007

61

Rajesh ABramhaprasad VPurohit AK: Traumatic rupture of arachnoid cyst with subdural hygroma. J Pediatr Neurosci 7:33352012

62

Rakier AFeinsod M: Gradual resolution of an arachnoid cyst after spontaneous rupture into the subdural space. Case report. J Neurosurg 83:108510861995

63

Rao GAnderson RCFeldstein NABrockmeyer DL: Expansion of arachnoid cysts in children: report of two cases and review of the literature. J Neurosurg 102:3 Suppl3143172005

64

Robinson RG: Intracranial collections of fluid with local bulging of the skull. J Neurosurg 12:3453531955

65

Russo NDomenicucci MBeccaglia MRSantoro A: Spontaneous reduction of intracranial arachnoid cysts: a complete review. Br J Neurosurg 22:6266292008

66

Sato HSato NKatayama STamaki NMatsumoto S: Effective shunt-independent treatment for primary middle fossa arachnoid cyst. Childs Nerv Syst 7:3753811991

67

Seizeur RForlodou PCoustans MDam-Hieu P: Spontaneous resolution of arachnoid cysts: review and features of an unusual case. Acta Neurochir (Wien) 149:75782007

68

Sener RN: Arachnoid cysts associated with post-traumatic and spontaneous rupture into the subdural space. Comput Med Imaging Graph 21:3413441997

69

Shim KWLee YHPark EKPark YSChoi JUKim DS: Treatment option for arachnoid cysts. Childs Nerv Syst 25:145914662009

70

Spacca BKandasamy JMallucci CLGenitori L: Endoscopic treatment of middle fossa arachnoid cysts: a series of 40 patients treated endoscopically in two centres. Childs Nerv Syst 26:1631722010

71

Struck AFMurphy MJIskandar BJ: Spontaneous development of a de novo suprasellar arachnoid cyst. Case report. J Neurosurg 104:6 Suppl4264282006

72

Tamburrini GCaldarelli MMassimi LSantini PDi Rocco C: Subdural hygroma: an unwanted result of Sylvian arachnoid cyst marsupialization. Childs Nerv Syst 19:1591652003

73

Tamburrini GDal Fabbro MDi Rocco C: Sylvian fissure arachnoid cysts: a survey on their diagnostic workout and practical management. Childs Nerv Syst 24:5936042008. (Erratum in Childs Nerv Syst 24: 635 2008)

74

Thomas BPPearson MMWushensky CA: Active spontaneous decompression of a suprasellar-prepontine arachnoid cyst detected with routine magnetic resonance imaging. Case report. J Neurosurg Pediatr 3:70722009

75

van der Meché FGBraakman R: Arachnoid cysts in the middle cranial fossa: cause and treatment of progressive and non-progressive symptoms. J Neurol Neurosurg Psychiatry 46:110211071983

76

Varma TRSedzimir CBMiles JB: Post-traumatic complications of arachnoid cysts and temporal lobe agenesis. J Neurol Neurosurg Psychiatry 44:29341981

77

Vernooij MWIkram MATanghe HLVincent AJHofman AKrestin GP: Incidental findings on brain MRI in the general population. N Engl J Med 357:182118282007

78

Vigil DVDiFiori JPPuffer JCPeacock WJ: Arachnoid cyst and subdural hygroma in a high school football player. Clin J Sport Med 8:2342371998

79

Weber FKnopf H: Incidental findings in magnetic resonance imaging of the brains of healthy young men. J Neurol Sci 240:81842006

80

Weber RVoit TLumenta CLenard HG: Spontaneous regression of a temporal arachnoid cyst. Childs Nerv Syst 7:4144151991

81

Weinberg PEFlom RA: Intracranial subarachnoid cysts. Radiology 106:3293331973

82

Yamanouchi YSomeda KOka N: Spontaneous disappearance of middle fossa arachnoid cyst after head injury. Childs Nerv Syst 2:40431986

83

Yokoyama KTonami NKimura MKinoshita AAburano THisada K: Scintigraphic demonstration of intracranial communication between arachnoid cyst and associated subdural hematoma. Clin Nucl Med 14:3503531989

84

Zada GKrieger MDMcNatt SABowen IMcComb JG: Pathogenesis and treatment of intracranial arachnoid cysts in pediatric patients younger than 2 years of age. Neurosurg Focus 22:2E12007

85

Zhang BZhang YMa Z: Long-term results of cystoperitoneal shunt placement for the treatment of arachnoid cysts in children. Clinical article. J Neurosurg Pediatr 10:3023052012

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