Turkish NeIIl'Osurgery 12: 59 - 62, 2002 Ziyn/: Arncll/loirl cyst with subdural hell/ntoll/II

withCase Report

Arachnoid Cyst AssociatedSubdural Hematoma: A

SylvianSpontaneous

(Spontan Subdural Hematom ileBir Olgu

Birlikte SylvianSunumu)

Araknoid Kist:

IBRAHiM M. ZiYAL, F AiK OZVEREN, MURAT Db$OGLU, MERiH i$, FERRUH GEZEN

The Abant Izzet Baysal University, Duzce Medical School, Department of Neurosurgery (iMZ,MD,Mi,FG), Duzce, TurkeyUniversity of FIrat, School of Medicine, Department of Neurosurgery (FO), Elazlg, Turkey

Received: 22.12.1999 ¢:> Accepted: 14.09.2000

Abstract: A 26-year-old male with a type II sylvianarachnoid cyst of the middle cranial fossa developedspontaneous subdural hemorrhage. The only presentingsign was headache. The hematoma was evacuated andduring surgery it was noted that the cyst wascommunicating with the subarachnoid and subduralspaces. Late postoperative radiological follow-up showedthat the arachnoid cyst has not resolved. This reportdescribes the details of the case.

Ozet: Tip II sylvian araknoid kisti olan 26 ya~ll1dakibir erkek hastada spontan subdural hematom tesbitedildi. Tek bulgu ba~ agnsl idi. Hematom bo~altlldl veameliyat esnasmda kistin subaraknoid ve subdur,libo~luk ile ili~kili oldugu gozlendi. Ge<; postoperatifradyolojik takip araknoid kistin rezoltisyonaugramadlgml ortaya koydu.

Key words: Arachnoid cyst, middle fossa, spontaneousrupture, subdural hematoma

Anahtar kelimeler: Araknoid kist, orta fossa, spontanruptlir, subdural hematom

INTRODUCTION

Intracranial arachnoid cysts are developmentalanomalies. The potential outcomes in these casesinclude resolution, no change in cyst size, gradualenlargement of the cyst, or spontaneous ruptur intothe subdural space (4,5,15). Spontaneous resolutionhas been documented in cases of ruptured cysts andin situations where the cyst has remained intact(3,14,15,21,22). Most ofthe arachnoid cysts associatedwith subdural hematoma have been diagnosedincidentally after head trauma (2,9,18,19,20);however, a few reports have noted these cysts

presenting with spontaneous subdural hematomas(2,3,17,18,20). We describe a rare case of type IIsylvian arachnoid cyst in which the patient's onlydiagnostic sign, headache, was caused by aspontaneous subdural hematoma.

CASE REPORT

A 26-year-old male was admitted to our clinicwith sudden onset of severe headache. The patienthad no history of trauma or systemic disease, norhad he performed Valsalva's maneuver. Hisneurological examination revealed no deficits. A

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Tllrkisll Nel/rosl/rgery 12: 59 - 62, 2002

computed tomography (CT) scan demonstrated anarachnoid cyst in the right sylvian region, and alsorevealed that the cyst was communicating with anacute subdural hematom (Figure 1). We evacuatedthe hematoma through a small temporoparietalcraniotomy, and were able to see the connectionbetween the cyst and the subarachnoid and subduralspaces. The patient did well after the operation. Acontrast-enhanced CT scan done one month

postsurgery revealed that the arachnoid cyst was stillpresent (Figure 2). Since the patient wasasymptomatic, we decided to follow him clinicallyand radiologically.

DISCUSSION

Arachnoid cysts are generally considered to bedevelopmental anomalies of the arachnoidmembrane that arise in the early intrauterine period.The lesion later causes secondary hypoplasia of theadjacent neural structures (5,7). The mechanismbehind cyst growth is not fully understood, but mayinvolve deficient communication between the spacesthrough which cerebrospinal fluid flows. It is alsonot clear how or why some of these cystsspontaneously resolve.

The hemorrhagic complications of arachnoidcysts include subdural, intracystic and extraduralhematomas that mayor may not be associated with

Figure 1: Thepatient's CTscanshows a hemorrhagic typeII sylvian arachnoid cyst on the right side. Thecyst is communicating with an acute subduralhematoma.

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Ziynl: Arnchl/oid cyst with ,Itbdl/rat llelllatnilia

head trauma (2,9,13,16,17,19,20). Fragileleptomeningeal vessels and bridging veins within thecyst or the cyst wall are the main sources of subduralbleeding 0, 8,12).Vascular conditions, membranousadhesions and reduced compliance may bepredisposing factors(3). Most subdural hematomasthat accompany arachnoid cysts are chronic in nature(2,9-13,16,17), and it has been reported that youngmen diagnosed with these cysts are at greater risk ofdeveloping subdural hematoma (11,13).Interestingly, our patient developed an acutesubdural hematoma without having suffered anyhead trauma.

Cysternographic studies are valuable fordemonstrating communication between the cyst andthe subarachnoid space (6,10). Galassi developed aclassification system based on cyst size and shape,an discovered an inverse relationship between cystsize and the degree of communication with thesubarachnoid space (6). Demonstration of thephysical connection is important for planning thesurgical treatment. In our case, the patient's CT scanshowed that the cyst was communicating with bothof the subdural hematoma and the subarachnoid

space. We were able to visualize blood collected inthe subdural, intracystic and subarachnoid spaces.

It is not uncommon for an arachnoid cyst toresolve spontaneously (3,14,21,22). Yamauchi and

Figure 2: Contrast-enhanced CT scan one monthpostsurgery shows that the arachnoid cyst hasnot resolved.

Tllrkish Nellrosllrgery 12: 59 - 62, 2002

colleagues reported the spontaneous disappearanceof such a lesion in a pediatric patient 5.5 years afterthe cyst had been diagnosed. They suggested thatsurgical treatment is not always indicated for a childwho developes an asymptomatic arachnoid cyst inthe middle cranial fossa. It was speculated that theirpatient's cyst ruptured due to crying and extremebreath holding. The authors' theory was that this hadincreased the intracystic tension and acceleratedspontaneous rupture (21). Once the cyst wall tearsspontaneously or something else leads tocommunication between the cyst and thesubarachnoid and/ or subdural spaces, the cyst is lesslikely to resolve if its internal pressure is equal to orlower than the pressure within the spaces. However,cyst resolution also depends on the elasticity of theunderlying brain tissue. Even when the pressureinside the cyst cavity is higher than that in thesubarachnoid and/ or subdural spaces, fenestrationwill not result in resolution if the elasticity of the brainis poor. Regarding medical treatment, one group ofauthors reported a single patient with an infectedarachnoid cyst that disappeared after antibiotictreatment alone (22).

Most cases of arachnoid cyst that present withclinical signs are treated surgically. This involvesfenestrating the cyst such that it communicates withthe subarachnoid space and in turn, the subduralspaces (2,7,13,16,17,19). In line with the conceptsexplained above, surgical fenestration yields betterresults when the intracystic pressure exceeds that inthe connected spaces. One surgical alternative fornoncommunicating cysts that are causing a masseffect on adjacent structures is to place a shuntbetween the cyst cavity and the peritoneum. In ourcase, we did preoperative rediological studies thatdemonstrated blood within a cystic lesion, andhemorrhage in the subdural and subarachnoidspaces. During surgery, we also confirmed thecommunication between the cyst and thesubarachnoid and the subdural spaces. This patient'scyst had undergone spontaneous fenestration. Sinceit was communicating with the subarachnoid space,we opted against placing a shunt. Instead, we drainedthe hematoma through a small craniotomy, brokedown adhesions that had formed between the cystwall and the arachnoid membrane, and then

surgically fenestrated the cyst to connect it with thesubarachnoid and subdural spaces. It is valid toquestion the need for surgical exploration in this case.We decided to treat the patient surgically on the basisthat eliminating the adhesions and draining both theclot and the cyst fluid would produce the most rapid

Ziya/: Arachlloid cyst with sllbdllrn/ heilla/oll/o

healing. The cyst remained visible on radiologicalfollow-up at 3 month, 6 month, and 1 yearpostsurgery. We attribute this to the pressure insidethe cyst being equal or lower than that in thesubarachnoid space. Parsch et. al advocatedconservative treatment for arachnoid cysts v.rithchronic subdural hematomas and hygromas,although they treated 14 of 16 cases in their seriessurgically (13). Conservative treatment may bepreferred in cases of chronic subdural hematoma;however, when there are clinical signs and acutebleeding, the method of choice is to remove the clotand drain the cyst contents into the subarachnoidspace. In conclusion, spontaneous subduralhematomas are rare complications of arachnoid cysts.Acute cases should be treated surgically.

Correspondence: Ibrahim M. ZiyalSusam Sokak Yuvam Apt. 20 / -l

Cihangir, Istanbul, TurkeyPhone: (90) 532 232 9702Fax: (90) 3745414105

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Ziyn/: Arachl/vid cyst with sl/iJdllml ht"1I111/0/1I11

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Otol Neurotol 2002 Jani23(1):84-92

Radiological differentiation of intracranial epidermoids from arachnoid

cysts.

Dutt SN, Mirza. S, Chavda SV, Irving RM.

Both arachnoids cysts and epidermoids are characteristically welldemarcated and have a homogeneous low density, similar tocerebrosinal fluid on computerized tomographic scan, showing nocontrast enhancement. On MRI, epidermoids and arachnoid cystsusually appear hypointense on Tl-weighted images and hyperintenseon T2-weighted images. On fluid-attenuated inversion recovery, anarachnoid cyst tends to follow cerebrospinal fluid intensity,whereas an epidermoid becomes hyperintense. On echo planardiffusion scanning, an epidermoid remains bright.

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