Bilateral middle cranial fossa arachnoid cysts. A case report.

The temporal lobe agenesis syndrome is a rare congenital abnormality. This syndrome frequently has been described in association with arachnoid cysts or abnormal collections of cerebrospinal fluid. Arachnoid cysts develop most frequently in the middle cranial fossa and almost all these cysts are unilateral. Bilateral middle cranial fossa arachnoid cysts are extremely rare and only 9 cases have been reported in the literature. We present an adult case with bilateral arachnoid cysts and temporal lobe agenesis whose mental examination and neurologic assessment is normal. The cysts are demonstrated by CT and metrizamid CT cysternography.     

Correction

Primary intracranial arachnoid cysts are not too infrequent, but cases involving a familial occurrence of arachnoid cysts or bilateral symmetrical cysts in one patient have rarely been reported. We report bilateral arachnoid cysts of the middle cranial fossa in siblings.     

Peculiarities of intracranial arachnoid cysts: location, sidedness, and sex distribution in 126 consecutive patients.

OBJECTIVE: To study the distribution of intracranial arachnoid cysts in a large and nonbiased patient population. METHODS: One hundred twenty-six patients with 132 arachnoid cysts were studied. Patients were consecutively referred to our department during a 10-year period from a well-defined geographical area with a stable population. RESULTS: The cysts had a strong predilection for the middle cranial fossa; 86 patients (65.2%) had cysts in this location. Of 106 cysts with clearly unilateral distribution, 64 were located on the left side and 42 on the right side. This significant difference resulted solely from the marked preponderance of middle fossa cysts for the left (left-to-right ratio, 2.1:1). There were significantly more males than females (92 males/34 females). This difference was exclusively due to male preponderance of unilateral middle fossa cysts (66 males/14 females; ratio, 4.7:1). For all other cyst locations, there was no difference between the two sexes (26 males/20 females) or the two sides (10 left, 16 right). The marked left-sidedness for middle fossa cysts was found only in males. Females had an even distribution between the two sides. CONCLUSION: Arachnoid cysts have a strong predilection for the middle cranial fossa that may be explained by a meningeal maldevelopment theory: the arachnoid coverings of the temporal and frontal lobes fail to merge when the sylvian fissure is formed in early fetal life, thereby creating a noncommunicating fluid compartment entirely surrounded by arachnoid membranes. Why males develop more middle fossa cysts on the left side remains a mystery.     

Spontaneous fluctuation in the size of a midline posterior fossa arachnoid cyst

Arachnoid cysts of the posterior fossa are rather uncommon compared with their supratentorial counterparts. Spontaneous disappearance of middle cranial fossa arachnoid cysts has been reported but there are none in the English literature on the spontaneous fluctuation in size of a posterior fossa arachnoid cyst. We present a 41-year-old male, with a midline posterior fossa arachnoid cyst, which appeared to lessen in size spontaneously with complete disappearance of symptoms and then enlarged with a worsening in neurological status.     

中颅窝蛛网膜囊肿的神经内镜手术治疗

目的 探讨中颅窝蛛网膜囊肿神经内镜手术的治疗经验并评估其治疗效果.方法 回顾2004年1月至2009年6月使用神经内镜行囊肿-脑池造瘘治疗中颅窝蛛网膜囊肿32例,其中男性21例,女性11例,年龄6个月～39岁,平均年龄8.4岁,包括5例幼儿患者,年龄2～5岁.分析病例的临床资料,包括临床症状、影像学表现、手术适应证、手术技巧、手术并发症以及临床及影像学随访结果 .结果 患者术后随访时间8～72个月,术前有症状的27例患者中,症状消失8例、改善17例、无变化2例,临床症状好转率为92.6%.5例术前无症状的幼儿患者,术后随访无新症状出现.囊肿消失4例,缩小20例,无明显变化8例.术后颅内感染及切口脑脊液漏各1例.无症状硬脑膜下积液4例.并发症发生率为18.8%.结论 神经内镜手术损伤小、效果好,可以作为中颅窝蛛网膜囊肿的首选治疗方法 .     

Heading injury precipitating subdural hematoma associated with arachnoid cysts--two case reports.

A 14-year-old boy and a 11-year-old boy presented with subdural hematomas as complications of preexisting arachnoid cysts in the middle cranial fossa, manifesting as symptoms of raised intracranial pressure. Both had a history of heading the ball in a soccer game about 7 weeks and 2 days before the symptom occurred. There was no other head trauma, so these cases could be described as "heading injury." Arachnoid cysts in the middle cranial fossa are often associated with subdural hematomas. We emphasize that mild trauma such as heading of the ball in a soccer game may cause subdural hematomas in patients with arachnoid cysts.     

Arachnoid cyst with traumatic intracystic hemorrhage unassociated with subdural hematoma

Arachnoid cysts of the middle cranial fossa may manifest themselves in several different ways. Most often they remain asymptomatic and are only diagnosed incidentally on computed tomography or at autopsy. When they are symptomatic, headache, nausea, vomiting and seizures are most common in the patients with increased intracranial pressure. Increased intracranial pressure is caused by the ball-valve mechanism of the cyst's membrane which is in communication with the general subarachnoid space or arachnoid cells which contain specialized membranes and enzymes which have secretory activity. A significant number of middle cranial fossa arachnoid cysts are associated with subdural hematoma which may, in turn, be associated with intracystic hemorrhage. We report an unusual case with posttraumatic, isolated intracystic hemorrhage of the arachnoid cyst in the sylvian area without subdural hematoma.     

Spontaneous disappearance of two asymptomatic arachnoid cysts in two different locations.

We report two children with asymptomatic arachnoid cysts which resolved spontaneously without any surgical intervention and history of major head and body trauma. The first child was a 10-year-old boy with an arachnoid cyst in the right sylvian fissure. The second child was a 1-year-old girl with a right cerebral convexity arachnoid cyst. Both of them were asymptomatic. Arachnoid cysts spontaneously disappeared within 2 years following initial diagnosing. There was no major head and body trauma except usual home, school and sports activity. We speculated that the cysts ruptured into cerebrospinal fluid circulation by the mechanical effects of some forced activities to the brain tissue and cyst, such as excessive breathing, coughing and sport activities. These factors may change the balance between intracystic and pericystic pressure and facilitate the rupturing of the cyst into subdural, subarachnoid and intraventricular spaces. These cases demonstrate that neurosurgical intervention of asymptomatic arachnoid cysts is not absolutely indicated in the paediatric age group. Close follow up with computerized tomography (CT) and magnetic resonance imaging (MRI) is a treatment option in the patient with arachnoid cysts located in the middle cranial fossa and cerebral convexity.     

Arachnoid Cyst in the Middle Cranial Fossa Presenting with Pulsatile Exophthalmos: Case Report and Literature Review

A 20-year-old woman suffered gradual progression of right pulsatile exophthalmos and slight headache. Computed tomography (CT) demonstrated outward and downward displacement of the right globe and an arachnoid cyst in the right middle cranial fossa associated with thinned and anterior protrusion of a bony orbit. Microscopic cystocisternotomy was performed and the cerebrospinal fluid (CSF) inside of the cyst communicated into the carotid cistern and cistern in the posterior cranial fossa. Pulsatile exophthalmos improved immediately after surgery. Arachnoid cyst in the middle cranial fossa presenting with exophthalmos is rare. Microscopic cystocisternotomy might successfully improve CSF flow and relieve exophthalmos.     

Bilateral symmetrical middle cranial fossa arachnoid cysts in a neonate

A newborn girl was admitted suffering from convulsive seizures in both legs. A computed tomography (CT) scan revealed bilateral symmetrical middle cranial fossa arachnoid cysts and intraventricular hemorrhage. In the course of a year, only the cyst on the right side became gradually larger; the cyst on the left side was reduced in size. At the age of 1 year and 2 months, her intellectual development was normal, but she could not stand by herself. On metrizamide-enhanced CT cisternography, the cyst on the right side was of a noncommunicating type. Membranectomy of the right-sided cyst was performed and the cyst proved to be of the intraarachnoid type. The postoperative course was uneventful and a CT scan, taken 10 months after the operation, revealed no abnormality on either side. The intellectual and motor development was normal, and no abnormality was observed by electroencephalography. This may be the first report of arachnoid cysts found in a neonate. It gives us clues for understanding the etiology of this disease, which has not been fully clarified.     

Intracranial arachnoid cysts in children. A comparison of the effects of fenestration and shunting

The best operative intervention for children with arachnoid cysts remains the subject of controversy. Recent reports stress that craniotomy for cyst fenestration is associated with a low incidence of morbidity and mortality and may leave the child shunt-independent. The cases of 40 pediatric patients with arachnoid cysts treated between 1978 and 1989 are reported. Five children with mild symptoms and small cysts that remained stable on follow-up studies have not required surgical intervention. Of 15 patients with cysts initially treated by fenestration, 10 (67%) showed no clinical or radiographic improvement postoperatively and have undergone cyst-peritoneal (eight patients) or ventriculoperitoneal (VP) shunting (one patient), or revision of a VP shunt placed for hydrocephalus before cyst fenestration (one patient). Two other patients with existing VP shunts required no further procedures. Thus, only three (20%) of 15 patients initially treated by fenestration remain shunt-independent after a median follow-up period of 8 years. The 20 other patients were initially treated by cysts shunting and all improved postoperatively; shunt revision has been necessary in six (30%) of these 20 patients because of cysts recurrence. Cyst location influenced the success of shunt treatment; none of the seven middle cranial fossa cysts treated by shunting have required revision, but results with cysts in other locations were less favorable. In all locations, though, shunting was more successful than fenestration. It is concluded that cyst-peritoneal or cyst-VP shunting is the procedure of choice for arachnoid cysts in most locations, including those in the middle cranial fossa.     

A case of arachnoid cyst in the middle cranial fossa presenting with trigeminal neuralgia

A 50-year-old man had been suffering from left trigeminal neuralgia for 30 years. CT scan revealed an arachnoid cyst occupying the anterior two-thirds of the left middle cranial fossa. Cerebral angiography showed elevation of the left middle cerebral artery and medial shift of the left posterior cerebral artery. Metrizamide CT showed that the cyst was not communicating with the subarachnoid space. Air CT revealed the root of the left trigeminal nerve in contact with the arachnoid cyst. The patient became completely free from the trigeminal neuralgia 6 months after cystoperitoneal shunt. This case seems to be a very rare case of trigeminal neuralgia caused by an arachnoid cyst.     

Giant prebulbomedullary arachnoid cyst. Case report and review of the literature

Usual locations of arachnoid cyst are the middle cranial fossa in 50-60%, cerebellopontine angle (10%) and suprasellar area (10%). Most of these malformations are asymptomatic. Premedullar arachnoid cysts are extremely rare. All previous cases reported were operated. We report a case of an asymptomatic giant craniocervical junction arachnoid cyst with a follow up of five years. In 2002, an adolescent consulted for persistent cervical pain. Encephalic MR showed a giant ventral craniocervical junction arachnoid cyst. Neurologic examination was normal. Conservative treatment was decided with a clinical follow up and repeated MR in case of persistent cervicalgia. Craniocervical junction arachnoid cysts are anecdotic. Medical care cannot be standardized. Pathogenesis and management are discussed.     

Paramedian hourglass epidermoid cysts extending in the middle and posterior cranial fossa

Four cases of large paramedian hourglass epidermoid tumors extending both in the middle and posterior cranial fossa are reported and other 16 cases from the literature are reviewed. The length of the clinical history and the triviality of neurological symptoms in spite of the size of the tumor are emphasized. CT scanning well documents the extension of these epidermoids and usually consents to differentiate them from the arachnoid cysts. The subtemporal transtentorial approach is more advisable, although a two-stage operation by subtemporal and suboccipital route can be necessary in some cases. Nevertheless the difficulties and the risk of the surgical treatment make very hard the complete removal of the tumor in most cases.     

Spontaneous disappearance of a large middle fossa arachnoid cyst

A case of a large middle fossa arachnoid cyst that spontaneously disappeared is reported. The possible mechanisms involved in the "natural cure" of this lesion and the indications for surgical versus conservative treatment of middle fossa arachnoid cysts are discussed.     

Intradiploic arachnoid cysts. Report of two cases

Two patients are presented in whom cranial arachnoid cysts developed as diverticuli of the arachnoid membrane through small defects in the dura mater, eroded through the inner table, expanded within the diploe, and eroded the outer table of the skull. Based on observations at the time of surgery and the histological examination of these lesions, it is proposed that they are congenital in origin. Previously reported cases of "traumatic arachnoid cyst without fracture," "intradiploic cerebrospinal fluid fistula," and "middle fossa pitholes" appear to represent the same pathological process as the lesions reported in this paper. It is proposed that "intradiploic arachnoid cyst" is the most appropriate term by which these lesions should be described.     

Intracranial arachnoid cyst and porencephaly of the middle fossa--its clinical and neuroradiological study

We reported four cases with well demarkated low density area in the middle cranial fossa, which was not enhanced with contrast medium and had the same absorption coefficient as the CSF. The operations and histological examinations revealed that two cases were arachnoid cysts and the others were porencephalic cysts. The clinicoradiological differential clues are listed below. 1) The porencephaly has intimate relation with focal neurological signs. 2) The thinning and bulging of the temporal bone are not a specific finding of an arachnoid cyst. Hemicranial atrophy, elevation of minor sphenoid wing and dilatation of paranasal sinuses in addition to focal bulging and thinning are indicative of porencephalic cyst. 3) Hemiatrophy of the brain and dilatation of the lateral ventricle on CT as well as the absorption coefficient of the brain surface facing the cyst are important finding of the porencephaly in differentiation. 4) The investigation of CSF dynamic is by no means helpful in differentiation between arachnoid cyst and porencephaly except intraarachnoid cyst. 5) The horizontal portion of the middle cerebral artery is not elevated in both two porencephalic cases. One of them showed a slight shift of anterior cerebral artery toward the affected side. An obstruction of the vessel is an important finding in porencephaly. 6) The electroencephalography can clearly demonstrate a porencephalic cyst as a localized slow focus, whereas it is not so remarkable in an arachnoid cyst.     

Middle fossa arachnoid cyst presenting an interesting clinical course: a case report

The mechanism of the disappearance of arachnoid cysts is not fully understood. We report a case of arachnoid cyst which disappeared after head injury. A 28-year-old male was found to have an arachnoid cyst in the left middle fossa following head injury. We followed him up, because he had no symptoms. Two weeks later, he suffered from severe headache. CT image showed a dilatation of the subdural space, and his symptom deteriorated. We performed subdural-perifocal shunt, but one month after, he developed a subdural hematoma. The subdural hematoma was irrigated through a burr hole. His symptom disappeared post operatively. Two months later, CT image showed the disappearance of subdural hematoma and the arachnoid cyst. This case suggested one of the mechanisms involved in the disappearance of arachnoid cyst after head injury.     

Arachnoid cysts of the middle cranial fossa accompanied by subdural effusions—experience with 60 consecutive cases

Background  

Subdural effusions (SDEs) can complicate arachnoid cysts of the middle cranial fossa (ACMFs). While there is a consensus that at least in adults asymptomatic ACMFs should not be operated, those with concomitant subdural and/or intracystic effusions are clinically apparent in the majority of cases and should be surgically treated. But it remains unclear, which surgical procedure is best.