Primary Arachnoid Cysts Research Articles

Primary arachnoid cyst - an early postoperative complication after microsurgical resection

Arachnoid cysts (AC) are benign, non-neoplastic fluid-filled malformations of the arachnoid tissue. Approximately 50-65% occur in the middle cranial fossa and predominantly on the left side, followed by retrocerebellar and convexity locations. Tremendous development and usage of cross-sectional imaging modalities suggest a higher prevalence of AC than previously thought. Since large arachnoid cysts express mass effect on surrounding neurovascular structures, a surgical approach is preferred to passive observation. Nevertheless, the symptomatology is frequently subjective and difficult to validate, and the causal link between symptoms and an arachnoid cyst is often dubious. Therefore, the operative indication and the best surgical modality for patients with AC remain controversial. Surgical options include opencraniotomy or endoscopic cyst fenestration, cystoperitoneal, cystosubdural, ventriculoperitoneal shunt insertion, or marsupialization via a craniotomy. The complications of these procedures include subdural hematomas, hygromas, hydrocephalus, cerebral edema, postoperative secondary arachnoid cyst, and, more rarely, remote intraparenchymal or subarachnoidal hemorrhage.

A New Classification for Pathologies of Spinal Meninges-Part 2: Primary and Secondary Intradural Arachnoid Cysts.

Spinal intradural arachnoid cysts are rare causes of radiculopathy or myelopathy. Treatment options include resection, fenestration, or cyst drainage. To classify intradural spinal arachnoid cysts and present results of their treatment. Among 1519 patients with spinal space occupying lesions, 130 patients demonstrated intradural arachnoid cysts. Neuroradiological and surgical features were reviewed and clinical data analyzed. Twenty-one patients presented arachnoid cysts as a result of an inflammatory leptomeningeal reaction related to meningitis, subarachnoid hemorrhage, intrathecal injections, intradural surgery, or trauma, ie, secondary cysts. For the remaining 109 patients, no such history could be elucidated, ie, primary cysts. Forty-six percent of primary and 86% of secondary cysts were associated with syringomyelia. Patients presented after an average history of 53 ± 88 months. There were 122 thoracic and 7 lumbar cysts plus 1 cervical cyst. Fifty-nine patients with primary and 15 patients with secondary cysts underwent laminotomies with complete or partial cyst resection and duraplasty. Mean follow-up was 57 ± 52 months. In the first postoperative year, profound improvements for primary cysts were noted, in contrast to marginal changes for secondary cysts. Progression-free survival for 10 years following surgery was determined as 83% for primary compared to 15% for secondary cysts. Despite differences in clinical presentation, progression-free survival was almost identical for patients with or without syringomyelia. Complete or partial resection leads to favorable short- and long-term results for primary arachnoid cysts. For secondary cysts, surgery can only provide clinical stabilization for a limited time due to the often extensive arachnoiditis.

Primary arachnoid cyst mimicking depressive symptoms in an elderly woman

We describe an 81-year old female patient who was seen at our outpatient clinic with a history of falls. The clinical diagnosis was concurrent with depressive symptoms, but an arachnoid cyst turned out to be the cause of her problems. The patient recovered completely after surgery.

Quality of life in adult patients with primary intracranial arachnoid cysts

Primary arachnoid cysts are benign developmental lesions of arachnoid mater. Arachnoid cysts may be detected due to various neurological symptoms, or they may be encountered as incidental findings of neuroimaging. Consequently, a significant share of the patients seems asymptomatic. There are diverging opinions about the clinical importance of cyst sizes, cyst location and degree of volume reduction after surgery, hence contributing to controversies regarding indications for surgical treatment. We present the first study assessing internationally established parameters of quality of life and mental health in a clinical-outcome analysis of adult patients with arachnoid cysts. Ninety-two adult patients with arachnoid cysts who had been referred to our department over the last 16 years were included. Forty-seven patients had undergone surgery and 45 patients had not been operated on. Data for analysis was based on both medical records and questionnaires sent out by mail. Quality of life was assessed by the Short Form 36 Health Survey (SF-36), and mental health was further evaluated by the Hospital Anxiety and Depression Scale (HADS). Seventy-one percent of patients responded to our questionnaires. There was a great variation in the presenting symptoms, seemingly without any relation to cyst localisation. Patients with arachnoid cysts seem to have a reduced quality of life and a very high prevalence of anxiety compared to a healthy normal population. Men presented lower outcome scores than women. Subjects with symptoms, that we retrospectively labeled biologically comprehensible, tended to have higher quality of life, less anxiety and better subjective symptom relief after surgery. Our arachnoid cyst population had a low employment status, decreased quality of life scores and prevalent symptoms of anxiety. We argue that the arachnoid cysts are, in most cases, not directly related to these studied parameters. We speculate that our findings may reflect the demographic characteristics of adults likely of being diagnosed with incidental cysts. A better clinical outcome for patients with biologically plausible symptoms supports a neurobiological approach in the selection of patients suited for surgery.

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.

Epilepsy accompanied by intracranial arachnoid cysts: studies on volume and regional cerebral blood perfusion using MRI and SPECT

To evaluate whether arachnoid cysts (ACs) can directly cause epilepsy by cortical compression, we studied the relationships among seizures, the volume of ACs, and regional cerebral blood perfusion around ACs. Subjects were 11 patients (10.5 ± 7.2 years) with primary intracranial ACs. The AC volume was calculated from axial T 1-weighted magnetic resonance imaging (MRI). N-isopropyl p-iodoamphetamine ( 123I-IMP) single photon emission computed tomography (SPECT) was used to evaluate cerebral blood perfusion. The lesional side to normal side ratio (L/N ratio) was calculated from rectangular and irregular region of interests (ROIs) in frontal and temporal area around the ACs. The volume of ACs in nonepileptic patients was significantly larger than in epileptic patients. In nonepileptic patients, SPECT demonstrated hyperperfusion around ACs, whereas in epileptic patients it showed hypoperfusion. The L/N ratio of rectangular ROIs in the posterior temporal area and irregular ROIs in the temporal area were significantly lower in epileptic patients than in nonepileptic ones. Our results suggest that epilepsy with ACs is related to the cerebral blood perfusion in the surrounding brain structures rather than to the volume of the ACs. Not only compression but also complicated brain parenchymal lesions may participate in the development of epilepsy.

Middle cranial fossa arachnoid cyst developing in infancy

The pathophysiology of primary arachnoid cysts of the middle cranial fossa is still unclear, and no widely accepted therapeutic criteria for this condition have been established. The authors present the case of a 7-year-old boy with this cyst accompanied by temporal lobe hypoplasia. On the basis of computerized tomography taken on the 2nd day after birth and magnetic resonance imaging upon admission, the arachnoid cyst in this case was attributed to brain hypoplasia secondary to abnormal arachnoid development and was confirmed to have developed primarily during infancy. Experience with this case yielded new findings useful in clarifying the pathophysiology of this condition and establishing therapeutic criteria for such a case.

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.

Clinicopathological study of the arachnoid cyst (author's transl)

Twenty-one cases of arachnoid cysts were experienced in the last 5 years. Craniotomy and extirpation of the arachnoid cysts were performed on 20 cases. Clinical features and histological findings of these cases were investigated. Ages of these patients ranged from 7 months to 70 years. Twelve cases (57%) were under the age of 20 years and the other nine cases (43%) were over 20 years old. The cysts were located in the middle fossa in 12 cases, in the frontal lobe in five cases, in the posterior fossa in three cases and in the left-sided hemisphere in one case. Symptoms were generally rather mild. Among the 12 cases of middle fossa arachnoid cysts, only six cases showed bony changes such as elevation of the sphenoid wing in plain skull films and of the 11 cases which underwent angiographic studies, only five cases showed poor visualization of the superficial middle cerebral veins on the affected side. Arachnoid cysts were readily diagnosed by CT examination as watery low density areas with a clear-cut margin which showed no enhancement by intravenous injection of contrast media. Metrizamide-CT and RI-cisternography were utilized in nine cases. Eight cases showed non-communicative cysts surrounded by metrizamide acummulation in the adjacent arachnoid space. Histological examinations of the cystic membrane were performed in eight cases by taking specimens from the covering part as well as from the bottom where the membrane adhered to the cortical surface. Seven out of eight cases showed duplicated normal arachnoid membrane. This finding indicated that the cysts could be regarded as “intraarachnoid cysts”, as pointed out by Starkman. Normal arachnoid membrane was examined histologically by taking specimens from lobectomized cortex as well as autopsied brain for comparison with the cystic membrane. These examinations revealed an interesting arachnoidal structure which might be termed “micro-intraarachnoid cysts” in certain instances. The etiology of the primary arachnoid cyst has been considered as congenital or developmental in nature. Starkman advocated that the structure of the intraarachnoid cyst itself indicated congenital malformation of the arachnoid membrane. However, this series included so many unexpected adult cases and also a case of posttraumatic arachnoid cyst in one identical twin. Therefore, one course of pathogenesis of the arachnoid cysts, can be postulated as a “microintraarachnoid cyst” existing in normal people starting to grow and becoming a large arachnoid cyst, triggered by some enlarging forces in head traumas or other unknown factors.

Diagnosis and treatment of intradural arachnoid cysts of the thoracic spine.

The majority of spinal arachnoid cysts are found in the posterior subarachnoid space and arise from or within the septum posticum. The septum posticum is a thin membranous partition which divides the posterior spinal subarachnoid space longitudinally, from the cervical to the lower dorsal region. It was first described in 1843 by Magendie (3), who found it to be composed of thin, transparent lamellae irregularly separated by small spaces of various shapes and sizes. This membranous partition was exhaustively studied by Key and Retzius (Fig. 1) (1). In later anatomical textbooks it is also called septum arachnoidale or subarachnoidale, septum cervicale intermedium, septum leptomeningicum dorsale, and septum posticum of Schwalbe. Primary arachnoid cysts arising within the layers of the septum posticum are rarely encountered in clinical practice. We believe, however, that such cysts, unassociated with arachnoiditis, form a definite clinical entity and deserve inclusion in a differential diagnosis of compressive lesions of the spinal cord. This report is based on the study of 2 cases. Case I: A 17-year-old girl gave a six-month history of mid and lower thoracic back pain that was non-radiating in character. Physical examination was negative. Roentgenograms of the thoracic spine suggested some widening of the interpedicular spaces of the 6th, 7th, 8th, and 9th dorsal vertebrae. On lumbar puncture, the spinal fluid was found to be under normal pressure and there was no evidence of subarachnoid block. The cerebrospinal fluid studies were normal. The symptoms persisted during the following eight months without producing obvious neurologic disturbances. Thoracic myelography was carried out with 9 c.c. of Pantopaque. With the patient in the prone position, there was no evidence of a lesion or subarachnoid obstruction, but when she was turned on her back, an ovoid structure filled with contrast material at the level of the 7th and 8th vertebral bodies and this persisted in the upright position (Fig. 3). On the lateral films it appeared to lie in the posterior half of the spinal canal and was suggestive of an arachnoid cyst (Fig. 4). Laminectomy of the 6th, 7th, and 8th thoracic vertebrae was carried out. The arachnoid appeared thin and transparent and there was no evidence of adhesions. The septum posticum was well developed and prominent and contained a cyst-like cavity measuring approximately 3 × 1.5 cm., filled with clear colorless fluid and Pantopaque. The cyst wall was thin and transparent and had the same appearance as the surrounding arachnoid. After evacuation of the contents, air was injected into the cyst, distending it. The arachnoid over the posterior aspect of the exposed cord containing the cyst was resected. The underlying cord looked grossly normal without evidence of flattening or compression. Convalescence was uneventful and recovery was complete.

Primary arachnoid cysts; report of two cases.

Primary arachnoid cysts; report of two cases.