Computed tomography of arachnoid cysts

Endoscopic transnasal transsphenoidal management of sellar/suprasellar arachnoid cyst: A case report and literature review

Background

Arachnoid cysts (ACs) are collections of cerebrospinal fluids (CSFs) that develop within the arachnoid layer of the meninges. Sellar ACs are comparatively rare. In general, ACs account for approximately 1% of all intracranial mass lesions, and sellar ACs are 3% of all intracranial ACs. An endoscopic transnasal transsphenoidal approach for the treatment of ACs by fenestrating the cyst's wall and connecting with the subarachnoid space is the most optimal option.

Case Description

A 74-year-old woman whose sellar AC was diagnosed on magnetic resonance imaging a year ago was admitted to our hospital with complaints of bitemporal hemianopia and diminished visual acuity in the past 2 months. Sellar AC was diagnosed based on the clinical history and presentation, as well as neurologic, endocrinologic, and ophthalmologic examinations, including visual acuity and visual field examination, and additional imaging findings. The patient with a sellar/suprasellar AC was treated by an endoscopic transnasal transsphenoidal approach with cyst drainage and perforation of the lamina terminalis. Postoperatively, the visual disturbances improved markedly. No surgery-related complications occurred.

Conclusion

The endoscopic transnasal transsphenoidal approach remains a minimally invasive and preferred approach for the treatment of sellar/suprasellar ACs. Hermetically reconstructing the sellar floor is an effective method to prevent CSF leakage.

Pituitary abscess following endoscopic endonasal drainage of a suprasellar arachnoid cyst: Case report and review of the literature

BACKGROUND

Arachnoid cysts are uncommon lesions of the sellar region, and only rarely require decompressive surgery to treat symptoms. Pituitary abscesses are another rare lesion, and are an uncommon complication of pituitary surgery. A previously healthy 45 year old woman presented with a new finding of bitemporal hemianopsia. Magnetic resonance imaging (MRI) showed a cystic sellar lesion with suprasellar extension and compression of the optic chiasm. Endoscopic transphenoidal surgery was performed and the lesion was found to be an arachnoid cyst. She was well immediately after the operation, but 1 week later presented with headaches, fever and worsening visual acuity. MRI showed a homogenous collection in the sellar region that was compressing the chiasm. The patient was treated with antibiotics, and a second transphenoidal operation was performed, with frank pus found in the pituitary fossa. Cultures of the fluid found during the operation grew Escherichia coli and Staphylococcus lugdunensis. Her symptoms resolved after the second operation, and formal visual fields and a pituitary hormone panel were normal at this time. We report on a rare case of a pituitary abscess complicating surgery for a sellar arachnoid cyst, and discuss management of these conditions.

Progressive sixth nerve palsy secondary to intracavernous arachnoid cyst and complicated by contralateral optic nerve sheath meningioma

INTRODUCTION

Optic nerve sheath meningiomas and intracavernous arachnoid cysts are both fairly rare conditions, and to the best of our knowledge, have not been previously reported to co-occur in the same patient. Both can cause diplopia, but only ONSMs have been documented to demonstrate progressive worsening of ocular motility.

CASE REPORT

A 67-year-old woman with blur and diplopia demonstrated a right optic neuropathy and limited ductions bilaterally. Neuroimaging revealed a right optic nerve sheath meningioma and left intracavernous arachnoid cyst. She was conservatively managed with neurosurgical surveillance for 1.5 years, until her diplopia worsened. Ocular motility re-evaluation demonstrated a worsening left abduction deficit, suggesting interval change of the intracavernous cyst, rather than the meningioma.

CONCLUSION

There are only a few reported cases of cranial nerve VI palsy secondary to a cavernous sinus arachnoid cyst. However, this is the first reported case in a patient with a concurrent optic nerve sheath meningioma, and the first case demonstrating progressive worsening of a sixth cranial nerve palsy from an intracavernous arachnoid cyst. Determining which comorbidity caused worsening of symptoms played a critical role in the management of this patient.

Pupil-sparing third cranial nerve palsy with aberrant regeneration secondary to cavernous sinus arachnoid cyst

A 66 year-old woman presented with a pupil-sparing partial third cranial nerve palsy with aberrant regeneration. Imaging revealed a cystic lesion in the right cavernous sinus, demonstrating signal characteristics consistent with arachnoid cyst. Oculomotor synkinesis and a pupil-sparing third cranial nerve palsy from an arachnoid cyst of the cavernous sinus have not been previously reported. Intracavernous arachnoid cysts are in the differential diagnosis of cranial nerve III palsies, with and without synkinesis or pupil involvement.

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Case of pupil-sparing partial third cranial nerve palsy with aberrant regeneration.

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Oculomotor synkinesis attributed to arachnoid cyst of the cavernous sinus.

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Intracavernous arachnoid cysts can cause cranial nerve III palsies.

Cerebral Aneurysm Associated with an Arachnoid Cyst: 3 Case Reports and a Systematic Review of the Literature

BACKGROUND

Arachnoid cysts and intracranial aneurysms are not rare, but it is unusual for an aneurysm to be associated with an arachnoid cyst. The objective of this study was to reveal the association between arachnoid cysts and intracranial aneurysms.

METHODS

Methods included to report 3 cases with these 2 pathologies and to perform a systematic review of the English and Japanese literature using PubMed, Scopus, and Ichushi Web.

RESULTS

The first case was of a 46-year-old man with a subarachnoid hemorrhage on the basal cistern and bilateral arachnoid cysts in the middle fossa, the second was that of a 29-year-old woman with a subarachnoid hemorrhage at the basal cistern and an arachnoid cyst in the left middle fossa, and the third was that of a 60-year-old man with a right putaminal hemorrhage and contralateral unruptured aneurysm and arachnoid cyst. A literature search for similar cases found 27 patients.

CONCLUSIONS

It was difficult to diagnose a ruptured aneurysm in some cases with an arachnoid cyst because computed tomography scan showed atypical findings, such as no hemorrhage, intracystic localized hemorrhage, or subdural hematoma. This review revealed that aneurysms and arachnoid cysts were significantly located ipsilaterally and that they occurred together in relatively young patients.

Altered cerebrospinal fluid dynamics in neurofibromatosis type l: severe arachnoid thickening in patients with neurofibromatosis type 1 may cause abnormal CSF dynamic

INTRODUCTION

The object of this study is to understand abnormal dynamic of cerebrospinal fluid (CSF) in patients with neurofibromatosis type 1 (NF1), which may cause temporal lobe herniation and bulging of temporal fossa.

METHODS

Four patients, three females and one male, with NF1 were studied retrospectively. They presented with a similar craniofacial deformity, which consisted of pulsatile exophthalmos, an enlarged bony orbit, dysplasia of the sphenoid wing with the presence of a herniation of the temporal lobe into the orbit, and a bulging temporal fossa.

RESULTS AND DISCUSSION

Surgical exploration demonstrated abnormally thickened arachnoid membrane in one case. Protruding temporal lobe, which was one of the main symptoms in NF1 patients, could be stopped by control of intracranial pressure (ICP) via programmable ventriculoperitoneal shunt (VPS) or extra ventricle drainage implantation. The dense fibrosis of the arachnoid membrane and consequent altered hemispheric CSF dynamics may cause symptoms including pulsatile exophthalmos and consequent worsening of vision, prolapse of the temporal lobe, and enlargement of the temporal fossa. This finding may not present with general features of hydrocephalus, so that delays in diagnosis often result.

CONCLUSION

For the NF1 patients with cranio-orbito-temporal deformities, prior to any surgical reconstruction, control of increased ICP (IICP) should be primarily considered.

Intrasellar arachnoid cyst: A case report and review of the literature

INTRODUCTION

Arachnoid cysts (ACs) are frequently found on intracranial imaging studies but intrasellar arachnoid cysts are rarely encountered.

PRESENTATION OF CASE

We present a 49-year old patient who had headaches for 6 months and cystic sellar mass was found in his cranial imaging. We operated him by transnasal transsphenoidal route. Our intraoperative diagnosis was an arachnoid cyst and pathologic studies verified our observation. He did well postoperatively and after a 1year follow-up he was left free from future follow-ups.

DISCUSSION

As common cystic lesions occupying the sellar region can simulate ACs both clinically and radiologically, neurosurgeon can fail to include ACs in making the initial diagnosis preoperatively.

CONCLUSION

Although a rare entity, arachnoid cysts should be considered in the differential diagnosis of sellar region.

The supposed intracavernous sinus arachnoid cyst with abducens neuropathy: a case report

Intracavernous sinus arachnoid cysts are rare intracranial congenital lesions. When present, their anatomic location frequently results in cranial nerve palsy. A 15-year-old boy was admitted to our hospital with diplopia, which had gradually worsened over the previous several months. An arachnoid cyst was identified within the right cavernous sinus and fenestration surgery was performed. The patient recovered well and three months after the surgery, diplopia was disappeared. Surgical decompression of the intracavernous sinus arachnoid cyst is beneficial for symptomatic patients with this condition.

Communicating hydrocephalus accompanied by arachnoid cyst in aneurismal subarachnoid hemorrhage

The authors describe a case of communicating hydrocephalus accompanied by an arachnoid cyst in an aneurismal subarachnoid hemorrhage. A 69-year-old female was referred to our clinic due to the sudden onset of a headache. A head computed tomography scan demonstrated an arachnoid cyst in the right middle fossa with a mass effect and diffuse subarachnoid hemorrhage. Digital subtraction angiography then revealed a left internal carotid-posterior communicating artery aneurysm. The neck of the aneurysm was clipped successfully and the post-operative period was uneventful. However, two months after discharge, the patient reported that her mental status had declined over previous weeks. A cranial computed tomography scan revealed an interval increase in the size of the ventricle and arachnoid cyst causing a midline shift. Simultaneous navigation guided ventriculoperitoneal shunt and cystoperitoneal shunt placement resulted in remarkable radiological and clinical improvements.

Endonasal management of sellar arachnoid cysts: simple cyst obliteration technique

Object

Symptomatic sellar arachnoid cysts (ACs) have typically been treated via the transsphenoidal route. After sellar cyst wall fenestration, some authors have advocated cyst wall resection and increasing communication between the AC and suprasellar subarachnoid space (SAS). This study is a report of the authors' experience using a simplified approach to reinforce a defective diaphragma sellae or unseen arachnoid diverticulum by deliberately not enlarging the AC-SAS communication and obliterating the cyst cavity with adipose tissue followed by skull base reconstruction.

Methods

A retrospective analysis was conducted of patients who underwent an endonasal transsphenoidal obliteration of symptomatic ACs with a fat graft and skull base repair.

Results

Between July 1998 and September 2010, 8 patients with a sellar AC were identified (6 women and 2 men, mean age 57 years). Clinical presentation included headache, pituitary dysfunction, and visual dysfunction (4 patients each group). Maximal cyst diameter averaged 22 mm (range 15–32 mm). In all cases the sellar communication to the SAS was deliberately not enlarged. The endoscope was used for visualization in 8 of 9 procedures. Postoperatively, headache improved in all 4 patients, vision in all 4 patients, and partial resolution of endocrine dysfunction (hyperprolactinemia and/or recurrent hyponatremia) occurred in 3 (75%) of 4 patients. No new endocrinopathy, CSF leak, meningitis, or neurological deficits occurred. Two patients experienced cyst reaccumulation: 1 symptomatic recurrence was treated with reoperation at 43 months postsurgery, and 1 asymptomatic partial recurrence continued to be monitored at 29 months postsurgery.

Conclusions

Sellar ACs can be effectively treated using endonasal fenestration and obliteration with fat with resultant reversal of presenting symptoms in the majority of patients. This simplified technique of AC cavity obliteration without enlarging communication to the SAS has a low risk of CSF leakage, and in most cases appears to effectively disrupt cyst progression, although longer follow-up is required to monitor for cyst recurrence.

Acute intracranial hypertension and shunt dependency following treatment of intracranial arachnoid cyst in a child: a case report and review of the literature

Arachnoid cysts are developmental anomalies that represent 1% of all intracranial space occupying lesions. Treatment of symptomatic cases may include shunting of the cyst or an open fenestration of it, among other less acceptable surgical procedures. Each procedure has its own pros and cons. We present a case of the development of an acute intracranial hypertension during cysto-peritoneal shunt malfunction in a child. We describe the possible mechanism of these phenomena and, based on this report and by reviewing other case series in the literature, we raise the possibility that acute increase in intracranial pressure and the development of shunt dependency, although rare, are important complications of shunting an arachnoid cyst.

Intracranial aneurysm and arachnoid cyst: a rare association between two cerebral malformations

Intracranial aneurysms and arachnoid cysts are cerebral disorders of a high prevalence. However, association between both malformations is a rare finding. The aim was to analyse this association with regard to the different clinical presentations according to the haemorrhage types, as well as the pathogenesis of this association. We searched the English language literature in MEDLINE database in order to include all manuscripts in which this association was found. A new case of a 55-year-old man with a large posterior communicating artery aneurysm and a middle cranial fossa arachnoid cyst presenting with headache and seizure was added to review of the literature and presented as an illustrative case. Nine cases were found. Six were male and three were female. The mean age was 42 years (range 29-66 years). All but one arachnoid cysts were located at middle cranial fossa, aneurysms arose from middle cerebral artery in three cases, internal carotid artery bifurcation in two cases, posterior communicating segment of carotid artery in two cases, anterior communicating artery in one case and azygos pericallosal artery in one case. Clinical presentation was related to aneurysmal rupture in six cases (subarachnoid haemorrhage in four, subdural haematoma in one and intracystic haematoma in two) and related to arachnoid cysts in three cases, where the most common symptoms were seizures and headache. Association between intracranial aneurysms and arachnoid cysts is a rare finding that can present with signs and symptoms related to aneurysm rupture, or with mass effect and seizures related to the cyst. The aneurysmal haemorrhage may be atypical, since it can be into the subarachnoid space, into the arachnoid cyst, or into the subdural space.

Intracranial arachnoid cysts: Current concepts and treatment alternatives

Arachnoid cysts are non-tumorous intra-arachnoid fluid collections that account for about 1% of all intracranial space-occupying lesions. In this article, we review the current concepts about these lesions and discuss the treatment alternatives. The aetiology of arachnoid cysts has been a controversial subject. They are regarded as developmental abnormality of the arachnoid, originating from a splitting or duplication of this membrane. The establishment of a single CSF space, by surgically communicating the cyst with the ventricular system or basal cisterns, appears to offer the best chance of a success in the treatment of arachnoid cysts. Long-term prognosis for patients with arachnoid cysts and well-preserved neurological conditions is good, even in the case of subtotal excision. Clinical follow-up and MRI allow earlier diagnosis of recurrence.

A FORM OF DYSPLASIA OR A FORTUITOUS ASSOCIATION? A CEREBRAL ANEURYSM INSIDE AN ARACHNOID CYST

OBJECTIVE

Although arachnoid cysts and intracranial aneurysms are very common lesions, their association in the same patient is rare. We present a case of a middle cerebral artery aneurysm ruptured into an arachnoid cyst. We found only six cases with intracystic hemorrhage reported in the literature. The presence of an arachnoid cyst can mislead clinical presentation. The patient presented a paradoxically small temporal fossa and thickening of the temporal and sphenoid bone. The authors suggest that this uncommon association (arachnoid cyst, atypical cranial vault, and “mirror-like” cerebral aneurysm) could represent a form of dysplasia.

CLINICAL PRESENTATION

A 46-year-old patient presented with a 3-week history of slight headaches, which had worsened in the last 3 days before presentation. Computed tomographic scans showed a cystic lesion located in the middle cranial fossa and sylvian fissure with suspected aneurysm dilation inside. Magnetic resonance imaging scans showed an intracystic hemorrhage but not subarachnoid hemorrhage. Paradoxically, changes in the cranial vault around the cyst were noted. Digital subtraction angiography showed bilateral “mirror” middle cerebral artery aneurysms.

INTERVENTION

A large right pterional craniotomy was performed with full microsurgical removal of the arachnoid cyst walls and aneurysm clipping. The aneurysm was in the medial wall of the arachnoid cyst with its dome inside the cyst. The contralateral aneurysm was clipped 2 weeks later. The follow-up period was uneventful, and the patient returned to normal life.

CONCLUSION

Rupture of a cerebral aneurysm into an arachnoid cyst is rare. Clinical presentation may be unusual because the cyst can prevent subarachnoid hemorrhage. A middle fossa cranial arachnoid cyst in the presence of temporal bone depression, small middle fossa, and thickness of squamous temporal bone and the lesser wing of sphenoid is rare and suggests that congenital factors may play an important role in their development. The exceptional association between “mirror” aneurysms and arachnoid cyst with bone changes suggests a possible congenital form of dysplasia.

Association between an arachnoid cyst and intracranial aneurysms misdiagnosed as a cystic tumor with a mural nodule

✓The authors report on a 63-year-old man initially admitted to an outside hospital for altered mental status and respiratory distress. A head computed tomography scan disclosed a right frontal cystic mass, suspected to be a neoplasm. An open biopsy was performed at an outside institution, and on visualization of the cyst, an aneurysm was found incidentally. Postoperatively, an angiogram and magnetic resonance image confirmed the presence of a distal right M1 segment aneurysm. The patient was transferred to our institution where, in addition to the middle cerebral artery lesion, a right anterior choroidal artery aneurysm was found intraoperatively; the necks of both aneurysms were clipped successfully. A review of the literature revealed 14 additional cases of intracranial aneurysms associated with arachnoid cysts. Data in the present report highlight the importance of considering an intracystic aneurysm in the differential diagnosis when reviewing cases that involve a cystic mass with a mural nodule. The authors provide a comprehensive summary of documented cases of aneurysms associated with arachnoid cysts. In addition, they include a discussion of prevailing thoughts on the origin and evolution of arachnoid cysts.

Idiopathic hypogonadotrophic hypogonadism associated with arachnoid cyst of the middle fossa and forebrain anomalies: presentation of an unusual case

We report a 22-yr-old male patient with hypogonadotrophic hypogonadism (HH) associated with a giant middle fossa arachnoid cyst (AC) diagnosed by magnetic resonance imaging (MRI). He presented with pubertal and growth delay. He also had learning disabilities and anosmia. Laboratory investigation revealed pre-pubertal levels of testosterone and normal results of the combined test of anterior pituitary function, except for in GnRH acute and prolonged test. Cranial MRI showed an AC in left middle fossa with expansion to suprasellar cisterna and several abnormalities like left temporal lobe hypoplasia, left optic tract and bilateral olfactory bulb hypoplasia and left hypothalamic hypoplasia.

Recurrent intrasellar arachnoid cyst

A 48-year-old man presented with complaints of decreased visual acuity persisting for 6 weeks in December 1997. Neurological examination demonstrated defects in the superior bitemporal visual field and bilateral optic atrophy. Computed tomography and magnetic resonance (MR) imaging showed an intrasellar cystic lesion. The cyst wall was excised via a transsphenoidal approach. The diagnosis was intrasellar arachnoid cyst. The sellar floor was reconstructed after packing fat in the sellar turcica. The visual complaint improved, but he was lost to follow up. Four years later, he was re-admitted complaining of decreased visual acuity. Superior bilateral field defects were found. MR imaging revealed recurrence of the intrasellar arachnoid cyst. The cyst wall was excised through a craniotomy. The visual acuity and the visual field defects gradually improved. Intrasellar arachnoid cyst may recur after transsphenoidal surgery, so long-term follow up is necessary after excision of the intrasellar cyst wall.

Symptomatic supratentorial arachnoid cysts in children

This study was undertaken to evaluate the clinical and radiologic long-term outcome of symptomatic primary arachnoid cysts in pediatric patients. Thirty-three children, ranging from 2 months to 17 years of age (mean age, 6 years) were treated. Craniotomy and fenestration of the cyst were used for temporal fossa and midline cysts in 24 patients (73%); later, two patients required shunt placement. Shunting device implantation was performed for cerebral convexity cysts in nine patients (27%), and two patients required a subsequent craniotomy and fenestration of the cyst. Four patients (12%) required additional surgery because of clinical progression rather than for cyst enlargement. Eleven patients (33%) experienced a cyst reduction of more than 50% compared with the original size on imaging studies. There was a significant correlation with the alleviation of symptoms (P < 0.005), regardless of the treatment used. Complete alleviation of symptoms was achieved in all patients after treatment, regardless of cyst reduction. Long-term follow-up of 70 +/- 9.3 months demonstrated no recurrence of symptoms or progressive enlargement of the arachnoid cyst in all children.

[Cerebral aneurysm and arachnoid cyst: about a case with intracystic hemorrhage]

We report a case of a carotid artery bifurcation aneurysm which ruptured into a silvian fissure arachnoid cyst. In the review of the literature, only three cases were before reported. We discuss about uncommon clinical findings, the surgical aspects and the associations among the lesions.

Arachnoid cysts of the posterior fossa

BACKGROUND

The surgical indications and management of posterior fossa arachnoid cysts (AC) are still controversial. Different surgical techniques and management have already been suggested for arachnoid cysts of the posterior fossa. AC involving the posterior fossa and especially the cerebellopontine angle may carry a high surgical morbidity because of the involvement of important neurovascular structures (e.g., brain stem and cranial nerves). Only long-term follow-up will determine the best surgical technique for such lesions.

METHODS

Between 1990 and 1996 a total of 12 patients underwent surgery for arachnoid cysts involving the posterior fossa. In seven cases AC were located within the cerebellopontine angle (CPA), in three cases in the CPA with major extension dorsal to the brainstem, and in two cases at the CPA extending into the internal auditory canal.

RESULTS

A suboccipital retrosigmoid approach was performed in all patients. Radical resection of the cyst could be accomplished in all but one case. There was no mortality. Major postoperative morbidity was present in one case because of an intraoperative air embolism in the semisitting position and strong adherence of the cyst wall to the surrounding neurovascular structures. Long-term follow-up (mean, 3.3 years) revealed improvement of most preoperative symptoms.

CONCLUSION

Open surgery and radical removal of the AC located at the posterior fossa, based on our retrospective analysis, provide very good long-term postoperative results. The suboccipital approach provides a good and safe exposure of vascular structures and cranial nerves in the CPA and allows radical resection of the cyst, reducing the chance of recurrence.

Magnetic resonance imaging and computed tomography characteristics of intracranial intra-arachnoid cysts in 6 dogs

Magnetic resonance imaging (MRI) and computed tomographic imaging (CT) characteristics of intracranial intra-arachnoid cysts in six dogs are described. Of the six dogs, three were less than one year of age and 4 were males. Five of the six dogs weighed less than 11 kg. Five cysts were located in the quadrigeminal cistern. On CT images, the intracranial intra-arachnoid cysts had sharply defined margins, contained fluid isodense to CSF and did not enhance following i.v. administration of contrast. On MRI images, the intracranial intra-arachnoid cysts were extra-axial, contained fluid isointense with CSF and did not enhance following i.v. contrast. While spinal arachnoid cysts of dogs have been reported in the literature, other than the six dogs contained in this report, intracranial intra-arachnoid cysts have not to our knowledge been described in animals. These six dogs have a similar age, sex, history, clinical signs, CT and MRI findings to those reported in people with intracranial intra-arachnoid cysts.

Intracranial arachnoid cysts: Treatment alternatives and outcome in a series of 25 patients

A series of 25 patients with intracranial arachnoid cysts is analyzed retrospectively. There were 14 males and 11 females ranging in age between a few days and 58 (mean 10) years. Seventy-six percent of patients were children below the age of 15 years. Most of the patients presented with symptoms and signs of long-standing raised intracranial pressure, while localizing signs were rather uncommon. The clinical manifestations were often mild relative to the large size of the cyst. Associated hydrocephalus was present in three patients: one with suprasellar cyst and two with posterior fossa cysts. Seven patients with mild symptoms and small cysts were treated conservatively, while the remaining 18 patients underwent surgical treatment. The initial surgical procedure consisted of craniotomy and fenestration of the cyst in three patients, and cystoperitoneal shunting in the other 15. Of the three patients who underwent craniotomy, one improved postoperatively, while the remaining two developed complications consisting of wound infection and postoperative epilepsy in one and permanent severe neurological deficit in the other. In contrast, six of the 15 cysts treated by shunting resolved completely, eight were smaller, and one remained unchanged. Radiological regression of the cyst after shunting was associated with various degrees of clinical improvement in 13 patients (87%). Two (13%) of 15 shunted patients developed complications in the early postoperative period, consisting of wound infection in one and early shunt failure in the other. Three patients (20%) with shunts had late complications during the follow-up period, consisting of recurrent shunt failure in the first, subdural hematoma in the second, and perforation of the peritoneal catheter into the hepatic bile ducts in the third. These findings, as well as recent data from the literature, suggest that in the management of intracranial arachnoid cysts, cystoperitoneal shunting was more effective and had fewer serious complications than craniotomy and cyst fenestration, and therefore, it is recommended as the treatment of first choice.

Arachnoid cysts of the cerebellopontine angle: diagnosis and surgery

OBJECTIVE

The optimal surgical management of arachnoid cysts remains controversial. The cerebellopontine angle (CPA) is a rare location for arachnoid cysts, and only 28 cases of arachnoid cysts occurring in the CPA have been reported in the literature. We discuss the diagnosis, radiographic imaging, and surgical management of CPA arachnoid cysts.

METHODS

Five patients (three male and two female patients) with a mean age of 5.6 years have been operated on at our institution since 1980. Magnetic resonance imaging allows for the accurate diagnosis of these arachnoid cysts, which can present with only discrete symptoms, such as headache or ataxia. All five arachnoid cysts compressed the cerebellum or brain stem. One patient had associated hydrocephalus. Three patients presented with refractory headaches associated with nausea and vomiting. The remaining two patients presented with cerebellar signs. No patient had an initial cranial neuropathy.

RESULTS

All patients underwent a retrosigmoid suboccipital craniotomy and microsurgical resection and fenestration of the cyst walls. One patient underwent two procedures. A cystoperitoneal shunt was inserted at the first operation. After the shunting procedure, the patient's condition deteriorated; however, after the microsurgical resection and fenestration, his symptoms improved. With a mean 5.2-year follow-up, there has been no evidence of clinical or radiographic recurrence.

CONCLUSION

Although CPA arachnoid cysts represent a small number of total arachnoid cysts, the CPA is the second most common location for arachnoid cysts to occur. CPA cysts are congenital lesions found in children who present with subtle signs or symptoms. The definitive treatment for these arachnoid cysts is a retrosigmoid suboccipital craniotomy and microsurgical resection and fenestration of the cyst walls.

Surgical options in the treatment of interhemispheric arachnoid cysts

BACKGROUND

Arachnoid cysts located within the interhemispheric fissure are a matter of discussion as to the surgical indication and the choice of the most appropriate surgical procedure. In fact, in spite of the large dimensions that they can reach, the clinical manifestations may remain subtle and apparently stable over the years. On the other hand, the larger utilization of prenatal ultrasound investigations has increased the number of lesions detected before they can provoke clinical manifestations. As far as surgery is concerned, two main options are available-an extrathecal shunting procedure or a direct approach to the lesion, with excision of its wall.

METHODS

In this report, we analyze the results obtained in 25 children harboring an interhemispheric arachnoid cyst, surgically treated in the period 1978 to 1994. Mean age at diagnosis was 18.8 months (10 days to 15 years). RESULTS The main clinical manifestations included macrocrania, mild to moderate signs of increased intracranial pressure, cranial bulging, developmental delay, and neurologic signs. In 14 cases, the diagnosis had been obtained prenatally. The cyst was located in one hemicranium in 16 cases, whereas it was on the midline, with bilateral extension, in the remaining 9 cases; in the latter cases, variable degrees of callosal agenesis were also observed. All 25 children were operated on. In 16 of them, the treatment consisted of a craniotomy with wide excision of the cyst lining and marsupialization into the subarachnoid spaces of the midline (and/or into the ventricular system). In 6 children, the surgical procedure was a cystoperitoneal (CP) shunt. The last 3 children of our series underwent craniotomy and cyst excision after having been treated by means of a ventriculoperitoneal shunt. At follow-up examination, 17 children are normal, and the remaining 8 disclose mild to moderate psychomotor retardation.

CONCLUSIONS

Although both craniotomy and CP shunt are associated with good results, the first surgical procedure offers the advantage of avoiding the insertion of a permanent cerebrospinal fluid shunt device and the known complications of this type of procedure.

Contrast-enhanced MRI of intrasellar arachnoid cysts: relationship between the pituitary gland and cyst

We recently encountered two large intrasellar arachnoid cysts extending to the suprasellar region. The intensity of the cyst contents was identical to that of the cerebrospinal fluid on both T1- and T2- weighted MRI. On contrast-enhanced MRI, the pituitary gland was compressed posteroinferiorly and flattened in the sella turcica. In this report of rare intrasellar arachnoid cysts the discussion is focused on dislocation of the pituitary gland.

Absence of the greater sphenoid wing in neurofibromatosis type I: congenital or acquired: case report

unilateral absence of the greater wing of the sphenoid bone is a distinctive but uncommon manifestation of Type I neurofibromatosis, which has until now been regarded as a developmental anomaly of mesodermal origin. A computed tomographic scan was obtained in a 4-week-old infant with an abnormal left eye. The scan demonstrated an intact ipsilateral sphenoid bone, except for minor expansion of the medial end of the left superior orbital fissure. Another computed tomographic scan was obtained 6 years later, when the child had café-au-lait patches, axillary freckling, Lisch nodules, and left phthisis bulbi. This later scan showed typical sphenoid dysplasia. Much of the greater wing was absent, and the anterior temporal pole was displaced anteriorly. In this article, we discuss the implications of this case in terms of the cause of this condition and the diagnosis of Type I neurofibromatosis.

Ruptured aneurysm associated with arachnoid cyst: intracystic hematoma without subarachnoid hemorrhage

BACKGROUND

It is well-known that arachnoid cysts of the middle fossa are associated often with chronic subdural hematomas and/or intracystic hemorrhages. However, reports of an arachnoid cyst associated with an aneurysm are rare.

CASE DESCRIPTION

A 45-year-old man was admitted with headache due to intracystic hemorrhage in the sylvian fissure, associated with a saccular aneurysm at the bifurcation of the internal carotid artery. The aneurysm ruptured into the arachnoid cyst, without causing a subarachnoid hemorrhage. Subsequently, the neck of the aneurysm was clipped successfully. The patient's postoperative course was uneventful, and there was no vasospasm.

CONCLUSIONS

This is the first reported case of an intracystic hematoma due to a ruptured aneurysm. We discuss the possible etiology of the association between the aneurysm and the arachnoid cyst, and the formation mechanism for the intracystic hematoma that did not result in a subarachnoid hemorrhage.

Mesencephalic and third ventricle cysts: diagnosis and management in four cases

Four infants with obstructive hydrocephalus caused by space occupying third ventricle and mesencephalic cysts are reported. Despite immediate shunt insertion in all patients, there was either lack of clinical improvement or late onset of clinical deterioration. Neuroimaging (CT, MRI, and ventriculography) diagnosed the presence of non-communicating midline outpouchings of the CSF pathways causing obstruction of aqueductal CSF flow and brainstem signs. The cysts were of different origin. In one patient it was caused by a previous thalamic haemorrhage, in another patient by neonatal Escherichia coli meningoventriculitis. In two cases with obstructive hydrocephalus at birth, the aetiology is unclear. Direct puncture and drainage of the cysts led to clinical improvement. The cysts were poorly visualised on CT and could be misinterpreted as an enlarged third ventricle, simulating congenital aqueduct stenosis. Careful neuroradiological investigation is necessary to establish an accurate diagnosis and neurosurgical management. In such cases with hydrocephalus and persisting ventricular enlargement despite shunting, CT ventriculography is a useful tool.

Endoscopic diagnosis and treatment of para- and intra-ventricular cystic lesions

Different cystic lesions can be located in or around the ventricular system, eventually causing hydrocephalus. Twenty-one patients are described where endoscopic intervention, mainly large fenestration towards the ventricular cavity, has been performed. This treatment can sometimes replace open surgery or extracranial shunting. Most rewarding are the arachnoid and ependymal intra- and paraventricular cysts. With careful and adequate endoscopic technique this procedure is safe and much less invasive than other methods described.

Endoscopic treatment of suprasellar arachnoid cysts

Four cases of large suprasellar arachnoid cysts in children are described. The authors propose a large fenestration into the lateral ventricles and into the basal cisterns as the treatment of choice. A specific multipurpose cerebral endoscope has been designed by the first author. The endoscopic technique with different instruments and with the use of a laser is illustrated. Results and complications are discussed.

Symptomatic intrasellar arachnoid cyst: case report

A case of a large symptomatic intrasellar arachnoid cyst with suprasellar extension is reported. A 53-year-old man was admitted because of decreased visual acuity. Magnetic resonance imaging showed a large intrasellar cyst extending into the suprasellar cistern, with compression of optic nerves. The intensity of the cyst was identical to that of the surrounding subarachnoid space on both T1-, T2-, and proton density-weighted images. Transsphenoidal surgery was performed, but subsequent refilling of the cyst required additional transcranial surgery. Analysis of the cerebrospinal fluid-like cystic fluid revealed high levels of protein and pituitary hormones. Histological study revealed that the cyst wall was composed of connective tissue and arachnoid cells, which were ultrastructurally characterized by a number of desmosomes. Diagnostic, surgical, and pathological features of intrasellar arachnoid cysts are discussed.

Primary intracranial arachnoid cyst in the elderly: a survey on 39 cases

Thirty-nine cases of primary intracranial arachnoid cyst in the elderly, including one case of our own, were analyzed. Clinical characteristics in these patients were as follows. (1) The number of patients decreased with age, but there were no differences according to sex. (2) Clinical manifestations were similar to those of chronic subdural haematoma or normal pressure hydrocephalus including dementia, urinary incontinence, and hemiparesis. General symptoms such as headache and seizures were also present. (3) Surgery was performed in most patients with generally good outcome regardless of operative procedures (capsular resection vs. shunt). (4) In some cases of advanced age, disease manifestation may have been due to slight head injuries.

Presentation and management of suprasellar arachnoid cysts. Review of 20 cases

The clinical presentation and treatment of suprasellar arachnoid cysts remain controversial. The authors review 20 cases treated at their institution and 86 cases from the literature reported in sufficient detail for analysis. The high frequency of endocrinological disorders, which not only persist following treatment but may also develop years later despite the satisfactory decrease in volume of the cyst, are emphasized and documented. The difficulties of management are discussed, including; subfrontal approaches to these cysts; removal and/or marsupialization of the cysts, procedures that are frequently dangerous and ineffective; and ventricular shunting which often leads to a paradoxical increase in the size of the cysts. The authors emphasize the advantages of percutaneous ventriculocystostomy, which is a simple, benign, and efficacious procedure.

Arachnoid cysts of the middle cranial fossa: a clinical, radiological and follow-up study

Twenty-seven patients with CT-scan-diagnosed arachnoid cysts in the middle cranial fossa were studied. Five (18%) presented with progressive symptoms related to raised intracranial pressure which had developed after minor trauma and secondary bleeding, 12 (44%) presented with non-progressive symptoms, and 10 (37%) exhibited neurological syndromes not referable to the cyst. Among those with non-progressive symptoms, epilepsy was the most common presentation (67%). More than 60% of the cysts were small and limited to the anterior temporal region or to the Sylvian fissure, the remaining cysts involved both the anterior temporal region and the Sylvian fissure, and expanded to the adjacent fronto-temporal or fronto-parietal regions. The volume measurements of the brain tissue performed on CT scan revealed that between the volume of the two hemispheres there was no significant difference suggesting any evidence of agenesis or hypoplasia of the affected temporal lobe.

Magnetic resonance imaging of arachnoid cysts

A retrospective review of magnetic resonance imaging (MRI)-computed tomography (CT) correlation was performed in 29 patients with arachnoid cysts. Short TR, short TE spin echo (SE) pulse sequences provided the best anatomic definition whereas multiple echo long TR, TE sequences allowed comparison of the signal intensity of the cyst with that of cerebrospinal fluid (CSF). Simple arachnoid cysts were isointense while neoplastic, hemorrhagic or inflammatory cysts were hyperintense relative to CSF. The CT differential diagnosis of an arachnoid cyst (depending upon its location) may include other cystic collections such as craniopharyngioma, epidermoid, astrocytoma, and chronic subdural hematoma. However, on MRI the combination of extra-axial location, morphological features, and signal intensity matching that of CSF allows one to make the diagnosis of an uncomplicated arachnoid cyst with confidence.

Intracranial arachnoid cysts in adults

Twenty-two cases of intracranial arachnoid cysts in adult patients have been studied and treated surgically. The authors analysed the correlation between the size and the location of the cysts and their clinical manifestations. It seems clear that the symptomatology and the problems of intracranial arachnoid cysts in the adult are quite different from those occurring with infants. The majority of our cases have been diagnosed by CT and NMR, and have been treated by open excision of the cystic membranes with the establishment of a wide communication with the basal cisterns or the subarachnoid space. With this technique the results have been very gratifying, while in cases managed with shunts the morbidity has been high.

A reappraisal of the relationship between arachnoid cysts of the middle fossa and chronic subdural haematoma

It has been increasingly recognised that patients with arachnoid cysts of the middle fossa appear more susceptible to the development of subdural haematomas. Seven patients with arachnoid cysts of the middle fossa and associated subdural haematomas are presented. Intra-cystic haemorrhage, masking the presence of an arachnoid cyst on computed tomography (CT) is highlighted. Repeat of CT scanning in young patients with subdural haematomas in the absence of severe trauma is recommended. Two theories are proposed to account for the observed susceptibility to the development of subdural haematomas in these patients.

Pediatric neurosonography

Neurosonography is an excellent modality for imaging a wide array of intracranial pathology in the infant and newborn. Neurosonography is also finding increasing use in other accessible regions of the central nervous system, including the adult brain during craniotomy and the spine during laminectomy. Sonography represents the primary modality for the evaluation of the preterm brain. Because of the high incidence of pathology in gestationally immature neonates, screening sonography is required in every infant. The sonographic features of intracranial hemorrhage include areas of increased echogenicity in the region of the germinal matrix, within the ventricles, or in the surrounding cerebral parenchyma. Careful follow-up of these children for sometimes severe posthemorrhagic hydrocephalus is essential. Premature neonates are also at risk for ischemic disease, particularly periventricular leukomalacia, which is accurately diagnosed sonographically and implies a poor prognosis in almost every infant so affected. Cranial sonography is also an excellent method to evaluate abnormalities that are not associated with gestational immaturity. Cranial sonography offers excellent anatomic imaging of the brain when evaluating for congenital anomalies; because sections may be obtained in a multitude of orientations, sonography is actually more versatile than computed tomographic (CT) scans. Cranial sonography is also of use when evaluating children with inflammatory processes such as ventriculitis; sonography is superior to CT scans in identifying intraventricular septae typical of the process. Intrauterine inflammatory processes, however, are frequently associated with intracranial calcifications, CT scans may be more accurate in these cases. CT scans may also be more efficacious in the diagnosis of subdural, epidural, and subarachnoid hemorrhage. Intracranial neoplasms are rare in the younger population and although they are visible with ultrasound, CT scans with contrast are essential in an effort to obtain added information and because of a greater experience using CT scans. Sonography represents an excellent modality with which to evaluate the infant and neonatal brain. In a number of diseases it may be diagnostic alone. The informed clinician, however, should keep in mind those instances where a complimentary modality such as CT scanning can add additional or even essential information.

Intracranial arachnoid cysts in children

The clinical and radiographic findings, surgical treatment, and outcome in 16 pediatric patients with intracranial arachnoid cysts are reviewed. The clinical presentation reflected the anatomical location of the lesions. Computerized tomography or magnetic resonance imaging scans were diagnostic in all cases. Of the nine cysts treated primarily or secondarily by craniotomy for fenestration and drainage into the basilar cisterns, five recurred. Cyst-peritoneal shunting led to diminished cyst size and clinical improvement in all seven cases in which it was used as the initial treatment and in all four cases in which fenestration had been unsuccessful. The results in this series show that cyst-peritoneal shunting is the treatment of choice for most intracranial arachnoid cysts in children.

Leptomeningeal cysts after spot freezing: transmission and scanning electron microscopic observations

The sequential development of the early phases of leptomeningeal cyst formation was studied in an experimental model. Light, transmission and scanning electron microscopic data were compared with those from human arachnoid cysts. Common features observed were: the participation of leptomeningeal cells in the structure of the cysts with exclusion of dural components; the absence of internal traversing trabeculae; the hyperplasia of leptomeningeal cells, particularly in the dome of the cysts. Other features of the experimental cysts were: the splitting of the pio-arachnoid membrane; the scarcity of collagen at the early stages; the presence of areas of mineralization at more advanced stages; the presence of remodeling parenchymal changes at the underlying nervous tissue.

Bobble-head doll syndrome: review of the pathophysiology and CSF dynamics

The bobble-head doll syndrome is a rare movement disorder; fewer than 40 cases have been reported. It is usually associated with cystic abnormalities in the region of the anterior third ventricle. Various physiologic mechanisms have been proposed but none of them has been substantiated. We report a patient with this syndrome produced by a suprasellar arachnoid cyst. The CSF dynamics were investigated with CT cisternography. The phenomenon was apparently the result of intermittent obstruction at the foramina of Monro, a feature which has not previously been reported in this condition. The head movement served to partially relieve intraventricular obstruction, by both a posterior displacement of the cyst away from the foramina of Monro and a reduction in cyst size. This finding supports the concept that the bobble-head syndrome may be a "learned" behavior which lessens the symptomatology of hydrocephalus related to foramina of Monro obstruction.

Treatment of supratentorial primary arachnoid cysts

Twenty-four cases of supratentorial primary arachnoid cysts operated with different techniques are reviewed: both cyst shunting or extirpation may lead to a good early clinical result, but the former is less dangerous and more indicated in a particular group of patients; late results are better in the shunted patients. CT scan is almost always diagnostic and is mandatory postoperatively to assess the late results.

Infratentorial arachnoid cysts

The infratentorial compartment represents the second most common location of arachnoid malformations. Ten arachnoid cysts of the posterior fossa, operated on between 1970 and 1983, are reviewed. These lesions, although congenital and developmental in nature, may present at any age, and males are more frequently affected. A high rate of birth-related trauma (50% in this series) is conceivably due to fetal macrocranium, and the enlarged head and psychomotor retardation prevail in infancy and childhood. In arachnoid cysts occurring during adulthood, symptoms and signs more clearly indicate a dysfunction of the posterior fossa. Besides computerized tomography, pneumoencephalography and metrizamide techniques are recommended to rule out a Dandy-Walker syndrome in doubtful cases, and to obtain information about the cerebrospinal fluid (CSF) circulation. It is particularly important to establish the presence and type of communication of cysts with the CSF pathways. Although infratentorial cysts often communicate, they can be space-occupying masses because of increasing CSF retention, which may be due to a ball-valve mechanism or to inadequate communication. The frequently associated hydrocephalus (seven of the 10 cases in this series had hydrocephalus) seemed to be dependent mainly upon mechanical factors. The authors discuss the indications for intracranial surgery versus shunting procedures and report the results achieved by direct cyst excision.