Clinical and magnetic resonance features of primary intracranial arachnoid cysts

Orbitofrontal approach for the fenestration of a symptomatic sellar arachnoid cyst

Background

Sellar arachnoid cysts (SACs) are rare lesions and incidentally found on brain imaging. The pathophysiology is poorly understood. Some authors suggested that SACs develop as a herniation of arachnoid membrane through the diaphragma sellae followed by cyst formation. Furthermore, Meyer et al. postulated that SACs are formed by splitting of the arachnoid layers. Symptomatic SACs present with headache, visual field deficit, or pituitary dysfunction. The data are limited on the indications and timing for intervention. We present a case of symptomatic SAC that was fenestrated using orbitofrontal approach.

Case Description

A 64-year-old female presented with chronic headaches and blurriness of vision. She was previously diagnosed with diabetes insipidus (DI) that was treated with desmopressin, magnetic resonance imaging (MRI) of her brain at that time was normal. Later on, she developed severe headaches that were managed medically. A year later, she had an episode of generalized seizure that led to the discovery of SAC on brain MRI. On examination, she had a left-sided monocular temporal hemianopia. The patient underwent an orbitofrontal craniotomy for fenestration of the SAC. At 6-month follow-up, her headaches had significantly improved with the resolution of the visual deficit. In addition, the DI had resolved, and the desmopressin was discontinued.

Conclusion

SACs are rare with no consensus on the indications for surgery. Our experience suggests that fenestration of SAC through transcranial approach is a valid option for patients with visual deficit and/or pituitary dysfunction.

Intraparenchymal supratentorial arachnoid cyst: a case report

Background

Intracranial arachnoid cysts are collections of cerebrospinal fluid within the arachnoid membrane and subarachnoid space of the cisterns and major cerebral fissures that account for about 1% of all intracranial lesions. Expansion of the cyst and compression on surrounding structures may became symptomatic, which reflects its size and anatomic distribution.

Case presentation

Here, we present a very rare case of patient with supratentorial intraparenchymal arachnoid cyst placed in the left frontal lobe without any communication with the subarachnoid space and ventricle and presented with clinical symptoms. The patient underwent fenestration of the lesion and was clinically improved.

Conclusions

Although the etiology and the enlargement mechanism of arachnoid cysts remain unclear, both conservative and surgical treatments are optional. According to size, anatomical location, neuroimaging, and clinical symptoms, an arachnoid cyst should be included in the differential diagnosis of primary intracerebral cysts.

Management of Neonatal Facial Paralysis due to Cerebellopontine Angle Arachnoid Cyst: A Case Report

Arachnoid cysts are benign, cerebrospinal fluid-filled collections that can be located in the brain or spinal cord. Arachnoid cysts form approximately 1% of all intracranial lesions. They are accepted as arachnoid developmental anomaly and arise from membrane splitting or duplication. Generally, lesion growth causes symptoms because of mass effect or obstruction. Arachnoid cyst growing mechanisms are a largely controversial issue. We report the case of a neonatal female patient who presented with congenital facial paralysis. Magnetic resonance imaging showed a right cerebellopontine angle arachnoid cyst causing severe mass effect on the brain stem. Cyst fenestration and cystocisternal shunt was performed through retrosigmoid suboccipital craniotomy.

Symptomatic Fourth Ventricle Arachnoid Cyst Extending to the Upper Border of the Dens of the Axis: A Case Report and Review of the Literature

Arachnoid cysts are congenital and non-tumorous intra-arachnoid fluid accumulations that make up about 1% of all intracranial space. occupying lesions. We report a patient with a fourth ventricle arachnoid cyst extending to the upper border of the dens of the axis. This patient progressively developed walking difficulty and stiffness in his legs together with difficulty in grasping objects with his hands within one year. The cyst was totally excised and the patient's symptoms improved in the early postoperative period, but he developed intraventricular and intracisternal air which was followed-up conservatively and resolved spontaneously.

Supratentorial Arachnoid Cyst Located in the Brain Parenchyma: Case Report

BACKGROUND AND IMPORTANCE:

Arachnoid cysts have not been reported to be located within the brain parenchyma. We present a case of an arachnoid cyst that was contained entirely within the right frontal lobe devoid of communication with the subarachnoid space and ventricle.

CLINICAL PRESENTATION:

A 65-year-old woman presented with a 1-year history of progressive headache and nausea. Computed tomographic and magnetic resonance imagining scans showed a well-defined, nonenhancing mass measuring 5 × 5 × 3.5 cm in the right frontal lobe. The mass appeared to be contained entirely within the brain parenchyma. The patient underwent a right frontal craniotomy, at which time the cystic mass was identified in the brain parenchyma without any communication with the arachnoid space. The cyst contained a clear fluid, and its wall was excised. The fluid contents demonstrated a composition similar to that of normal cerebrospinal fluid. Histological and immunohistochemical examinations of the cyst wall were compatible with the diagnosis of an arachnoid cyst. Postoperatively, the symptoms of the patient resolved, and no recurrence was observed up to 6 months after removal.

CONCLUSION:

The present case showed an intraparenchymal arachnoid cyst arising in the frontal lobe. Although the etiology is not known, an arachnoid cyst should be included in the differential diagnosis of primary intracerebral cysts.

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.

INTRASELLAR ARACHNOID CYSTS

OBJECTIVE

To evaluate the clinical, endocrinological, and radiological presentation of nine cases of surgically verified intrasellar arachnoid cysts and to discuss the physiopathological mechanisms of formation of these cysts.

METHODS

Among 1540 patients presenting with pituitary lesions, nine presented with an intrasellar arachnoid cyst. Their charts were retrospectively reviewed.

RESULTS

Presenting symptoms included headache (n = 2), visual symptoms (n = 3), menstrual irregularities (n = 2), rapid weight gain (n = 1), vertigo (n = 1), and/or confusion (n = 1). Two cysts were discovered incidentally. T1-weighted magnetic resonance imaging scans showed an intrasellar cystic lesion in all cases, with a huge suprasellar extension in six cases. The cyst was of the same intensity as the cerebrospinal fluid (CSF) in only two patients. A transsphenoidal approach allowed the transdural aspiration of fluid and injection of a water-soluble contrast agent under mild pressure. In three patients, the contrast infiltrated along the pituitary stalk toward the subarachnoid spaces; in the other patients, it remained in the intrasellar compartment. Cyst membranes were removed as completely as possible with fenestration toward the subarachnoid spaces in communicating cysts. In spite of tight packing of the sella and sphenoid sinus, CSF fistulae requiring reoperation developed in two patients.

CONCLUSION

The clinical picture of an intrasellar arachnoid cyst resembles that of a nonfunctional pituitary adenoma. Magnetic resonance imaging scans typically show a cystic intrasellar lesion with suprasellar extension, containing isointense or, more often, hyperintense fluid on T1-weighted sequences. In spite of the risk of CSF fistulae, the preferred surgical approach is transsphenoidal. A physiopathological mechanism is proposed according to anatomic variations of the sellar diaphragma allowing penetration of subarachnoid spaces into the sellar compartment and their enlargement by a ball-valve mechanism.

Differentiation between pediatric spinal arachnoid and epidermoid-dermoid cysts: is diffusion-weighted MRI useful?

BACKGROUND

Appropriate differentiation between epidermoid-dermoid and arachnoid cysts is important for patient management. MRI has had limitations in differentiating these two types of cysts, especially in the region of the spinal cord.

OBJECTIVE

To evaluate the role of diffusion-weighted (DW) MRI for differentiation between spinal arachnoid and epidermoid-dermoid cysts.

MATERIALS AND METHODS

Four children underwent conventional and DW MRI. Turbo spin-echo imaging was used to obtain DW images.

RESULTS

On conventional MRI, low T1-W and high T2-W signal was present in all lesions. DW imaging showed restricted diffusion in two patients with epidermoid-dermoid cysts and no water restriction in two patients with arachnoid cysts. Three of four children had extramedullary lesions and one patient had an intramedullary lesion. Three children had surgery, two with epidermoid-dermoid cysts and one with arachnoid cyst. Diagnosis was confirmed by histopathology. One child with a thoracic arachnoid cyst had stable clinical imaging findings during a follow-up of 21 months.

CONCLUSION

On conventional MRI, epidermoid-dermoid and arachnoid cysts have similar signal characteristics. Initial experience with spine DW imaging shows promise in differentiating epidermoid-dermoid cysts from arachnoid cysts. Preoperative differentiation is important because it changes management and surgical approach.

"Benign" imaging abnormalities in children and adolescents with headache

OBJECTIVE

To study the frequency of "benign" abnormalities on brain imaging in children with headache, compare it with the frequency of imaging findings that dictate a change in patient management, and determine the association of benign findings with headache.

METHODS

A database of 681 headache patients from the pediatric outpatient neurology department over 2 years was reviewed. Patients with benign imaging abnormalities were compared to those with nonbenign findings. Benign abnormalities were defined as those that did not result in a change in patient management. Using literature review, we discuss the benign findings and their possible association with headache.

RESULTS

Two-hundred and forty-one patients (35.4%) had imaging at our facility. Two-hundred and eighteen had brain magnetic resonance imaging and 23 had brain computed tomography (CT) only. Twenty-two patients had CT of the sinuses in addition to brain imaging. Forty-six (19.1%) were found to have 50 benign abnormalities including 13 sinus disease, 11 Chiari I malformations, 7 nonspecific white matter abnormalities, 5 venous angiomas, 5 arachnoid cysts, 4 enlarged Virchow-Robin spaces, 2 pineal cysts, 1 mega cisterna magna, 1 fenestration of the proximal basilar artery, and 1 periventricular leukomalacia. Twenty-three patients (9.5%) had findings requiring a change in management. These included 5 sinus disease, 4 tumors, 4 old infarcts, 3 Chiari I, 2 moyamoya, 1 intracranial vascular stenosis, 1 internal jugular vein occlusion, 1 arteriovenous malformation, 1 demyelinating disease, and 1 intracerebral hemorrhage. When excluding sinusitis, which was evident clinically prior to imaging, 3 patients had absence of abnormal neurologic symptoms and signs and imaging findings that resulted in a change in management.

CONCLUSIONS

Approximately 20% of pediatric headache patients with brain imaging have benign abnormalities that do not result in a change in headache management. Imaging findings that require a change in management are rare in patients with an absence of abnormal neurologic symptoms and signs, occurring in 1.2% of patients imaged in this study.

Cystic meningiomas in 2 dogs

Two dogs with signs of forebrain disease had hypodense lesions on computed tomography evaluation. Magnetic resonance imaging of the first dog showed a hypointense lesion on the T1-weighted scan and a hyperintense lesion on T2-weighted scanning. At surgery, both dogs had a primary cystic intracranial lesion, and the abnormal tissue adjacent to the cyst had histological features of meningioma. Each dog underwent whole brain irradiation after surgery, and 1 dog lived for 3 years after treatment. While uncommon, meningioma should be considered as a differential diagnosis in dogs with cystic intracranial lesions.

Arachnoid cysts in adults: experience with internal shunts to the subdural compartment

Twelve patients (10 males, 2 females) with symptomatic arachnoid cysts of the middle cranial fossa (9 patients) or overlying the frontal cortex (3 patients) were included. Under local anesthesia, an internal shunt was implanted from the cyst to the subdural compartment. Postoperative computed tomography scans showed volume reduction in eight patients. Permanent clinical improvement was also seen in eight patients. In the remaining four, the improvement was only temporary or partial, necessitating additional surgery in three patients. Complications (two subdural hematomas, one subdural infusion), were observed in three patients, all with large cysts. The complications were treated without sequelae. Internal shunts may be tried in adults as the first treatment for this condition.

Arachnoid cysts of the left temporal fossa: impaired preoperative cognition and postoperative improvement

Thirteen adult patients were operated on for symptomatic arachnoid cysts in the left temporal fossa; seven with an internal shunt procedure during local anaesthesia, and five with a craniotomy with fenestration of the cyst to the basal cisterns. In one patient, an initial internal shunt was transformed to a cystoperitoneal shunt. After surgery, all patients experienced relief of symptoms. Reduction of cyst volume occurred in 11 patients. The patients were tested for brain asymmetries related to language and verbal memory before and after operation, with a dichotic listening technique with simultaneous presentation of different auditory stimuli to the two ears. In the preoperative memory test, the patients showed impaired total recall compared with healthy control subjects, and recall from the right ear was significantly impaired. The patients also performed poorly in a forced attention task consisting of dichotic presentations of consonant-vowel syllables. In addition to clinical improvement, the surgical procedures led to improvements in both dichotic perception and memory. Overall memory performance was enhanced, mainly because of improved recall from the right ear. This normalisation of memory function was found as early as four hours after the operation. The results indicate that arachnoid cysts in the left temporal fossa may impair cognitive function, that neuropsychological tests are necessary to disclose these impairments, and that cognitive improvement occurs after surgery.

Supratentorial arachnoid cysts: clinical and therapeutic remarks on 46 cases

The authors report 46 cases of primary supratentorial arachnoid cysts. Thirty-two patients presented with symptomatic arachnoid cysts, which act as space-occupying lesions and were surgically treated by fenestration. 14 patients presented with a scarcity of symptoms; for this reason they were kept under control by periodical neuroradiological examination. After a long follow-up period (median 11 years), 97% of the operated patients presented neurological improvement and a decrease in the size of the cyst; none of the patients who were not operated on showed any variation in either neurological status or size of the cyst. The authors discuss their findings in the light of the published papers.

Arachnoid cysts: does surgery improve epileptic seizures and headaches?

During the period from 1985 to 1992 we treated 43 patients with intracranial arachnoid cysts (ACs). In this retrospective study we assessed the outcome of these patients with regard to non-specific symptoms such as headaches and epileptic seizures. Twelve patients had headaches of obscure origin and a mostly temporal located AC. Six of these 12 underwent surgery. After the operation 4 patients (4/6) had no further headaches, two remained unchanged. The other 6 conservatively treated patients (6/12) had further headaches. Ten of the 43 patients had epileptic seizures. One patient dropped out of the survey. Six of the 9 remaining patients had a temporal AC. Four of these 6 underwent surgery; postoperatively the seizure disease of 3 patients (3/6) declined. One patient was unchanged. Two patients with epileptic seizures and a temporal AC did not undergo surgery and both improved. Three patients with seizures had a convex located AC. Two of these 3 underwent surgery. The first patient improved postoperatively, the second patient remained unchanged. There was a reduction in the seizures of the medically treated patient. It remains ambiguous, whether there is a relationship between epileptic seizures and intracranial ACs without obvious intracranial pressure signs. A review of the literature, however, showed mostly positive results concerning the surgical treatment of ACs under conditions of simultaneous epileptic seizures. However, the results largely depend upon the definition of the decline of the seizures with regard to the postoperative follow-up, therefore we must remain skeptical. Therapy guidelines in the future not only depend on the clarification of the pathophysiology of the ACs, but also on a resonable outcome examination.

Neuroimaging of meningeal disease

In the past two decades, the advent of CT and MRI has made a considerable impact on the evaluation of meningeal diseases, conditions once regulated to cytological, histopathological, or postmortem analyses alone. This article reviews the imaging findings in various meningeal processes with particular attention to the anatomic definition of the meningeal layers and their relationship to the development of meningeal pathology and consequent imaging characteristics.

The "pseudo-CSF" signal of orbital optic glioma on magnetic resonance imaging: a signature of neurofibromatosis

A five-and-a-half-year-old boy with neurofibromatosis had bilateral orbital optic gliomas visible on magnetic resonance imaging. Both tumors displayed a double-intensity signal characterized by a circumferential area of CSF-intensity tissue surrounding and sharply delimited from a central linear core of opposite signal intensity. The peripheral CSF-intensity signal in orbital optic glioma correlates with the histopathological finding of perineural arachnoidal gliomatosis and serves as a neuroradiologic marker for neurofibromatosis.

Gender distribution and sidedness of middle fossa arachnoid cysts: a review of cases diagnosed with computed imaging

According to earlier reports, arachnoid cysts seem to occur more frequently in males, and on the left side. The latter phenomenon could, however, be explained by a greater significance attributed to symptoms from the dominant hemisphere as a justification for invasive procedures in the pre-computed tomography era. The literature from the last third of the era of computed tomography is reviewed with respect to gender distribution and sidedness for middle fossa arachnoid cysts. Also included are a few cases of our own from the same period. It is evident from this survey of the literature, based on computed tomography studies, that there is a significant tendency for these cysts to occur in males, with a male/female ratio of nearly 3:1. This preponderance toward males could not be explained by the somewhat higher frequency of associated subdural hematomas that was found in male patients. The survey also showed that middle fossa arachnoid cysts occur or are detected significantly more frequently on the left side than on the right, with a ratio of 1.8:1.

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.

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.