Tumefactive cyst with a vascular blush as a late complication after combined embolization and stereotactic radiosurgery treatments for a cerebral arteriovenous malformation

Summary Cyst formation is a recognized late complication after stereotactic radiosurgery for cerebral arteriovenous malformations (AVMs). We report on a patient with delayed cyst formation after combined embolization and stereotactic radiosurgery treatments for a cerebral AVM. The true nature of the cyst was complicated by tumefactive magnetic resonance MR imaging characteristics. The tumefactive cyst was associated with an additional imaging finding suggestive of a neoplastic lesion – a ‘blush’ on conventional angiography.     

Case Report: Optic Disc Edema without Hydrocephalus in Acoustic Neuroma

Traditionally, visual disturbance and optic disc edema are regarded as late manifestations of acoustic neuromas indicating increased intracranial pressure as a result of obstructive hydrocephalus or a sizeable mass lesion. We report the case of a 56-year-old man who presented with visual disturbance and bilateral optic disc edema. Classic features of hydrocephalus were absent. Magnetic resonance imaging showed a large acoustic neuroma. However, there was no ventriculomegaly and at surgery intracranial pressure was normal. We suggest that cerebrospinal fluid protein may have a role in the formation of optic disc edema through a normal pressure communicating type of hydrocephalus. Furthermore, patients with acoustic neuromas and a visual disturbance related to optic disc edema may be inappropriate for treatment with stereotactic radiosurgery and should be offered early surgery to prevent visual deterioration.     

Interactive magnetic resonance imaging-guided management of intracranial cystic lesions by using an open magnetic resonance imaging system.

OBJECT: The authors present their experience with neurosurgical procedures requiring real-time imaging feedback such as aspiration of a cystic structure or abscess cavity, decompression of hydrocephalic ventricles, management of arachnoid cysts, and installation of permanent or temporary drainage conduits, in which interactive magnetic resonance (MR) imaging guidance was used to monitor structural alterations associated with the procedure. METHODS: Drainage of eight intraparenchymal brain abscesses in seven patients, decompression of space-occupying cystic or necrotic brain tumors in four patients, and endoscopic management of hydrocephalus associated with arachnoid cysts in three patients were performed using MR imaging-guided frameless stereotaxy in an open-configuration 0.5-tesla superconducting MR imaging system. Intraoperative MR imaging guidance provided accurate information on the course of the surgical procedure and associated intraoperative changes in tissue position, such as the degree of cyst aspiration, the presence or absence of hemorrhage or induced swelling, and changes associated with decompression of adjacent brain parenchyma and the ventricular system. No clinically significant complications were encountered in any patient. There were no targeting errors, and procedural objectives were accomplished in all cases. CONCLUSIONS: Drainage of brain abscesses, punctures of cystic or necrotic intracranial lesions with subsequent aspiration, and management of hydrocephalus can be performed safely and accurately by monitoring the procedure using real-time MR imaging to obtain immediate feedback on associated dynamic tissue changes.     

Glioblastoma multiforme occurring in a patient treated with gamma knife surgery. Case report and review of the literature

Stereotactic radiosurgery is being increasingly advocated as the primary modality for treatment of vestibular schwannomas (VS). This modality has been shown to arrest tumor growth, with few associated short-term morbidities, and with possibly better hearing and facial nerve preservation rates than microsurgery. Radiation-induced oncogenesis has long been recognized, although stereotactic radiosurgery de novo induction of a secondary tumor has never been clearly described. The authors report on a patient with a VS who did not have neurofibromatosis Type 2 and who underwent gamma knife surgery (GKS). This patient required microsurgical removal of the VS within 8 months because of development of a tumor cyst with associated brainstem compression and progressive hydrocephalus. The operation resulted in clinical stabilization and freedom from tumor recurrence. Seven and a half years after undergoing GKS, the patient presented with symptoms of raised intracranial pressure. Magnetic resonance imaging demonstrated a new ring-enhancing lesion in the inferior temporal lobe adjacent to the area of radiosurgery, which on craniotomy was confirmed to be a glioblastoma multiforme (GBM). Despite additional conventional external-beam radiation to the temporal lobe, the GBM has progressed. Whereas this first reported case of a GBM within the scatter field of GKS does not conclusively prove a direct causal link, it does fulfill all of Cahan's criteria for radiation-induced neoplasia, and demands increased vigilance for the potential long-term complications of stereotactic radiosurgery, and reporting of any similar cases.     

Malignant squamous degeneration of a cerebellopontine angle epidermoid tumor. Case report

The authors present the case of a woman with a cerebellopontine angle (CPA) epidermoid cyst that degenerated into a squamous cell carcinoma. Malignant degeneration of an epidermoid cyst is an extremely rare occurrence. Malignant transformation must be considered in the differential diagnosis when new contrast enhancement on imaging studies and progressive neurological deficit are seen in a patient harboring an epidermoid cyst. The patient initially presented with a 10-year history of left trigeminal neuralgia, subacute left-sided hearing loss, and with facial weakness of 3 weeks' duration. Initial magnetic resonance (MR) imaging revealed a left CPA mass, consistent with an epidermoid. There was faint contrast enhancement where the tumor was in contact with the lateral brainstem. A subtotal resection was performed. Histopathological findings were consistent with an epidermoid tumor. One year after initial presentation, the patient's neurological deficit had increased, and follow-up MR imaging demonstrated a large contrast-enhancing tumor filling the left CPA and compressing the brainstem. At repeated surgery a squamous cell carcinoma arising from the previous epidermoid was found. The patient was subsequently treated with external-beam radiotherapy and stereotactic radiosurgery. Her tumor stabilized. Three years and 8 months after the patient's initial presentation, a new area of tumor developed at the torcular Herophili. The patient died shortly thereafter. Malignant squamous degeneration is a rare cause of enhancement on MR images, as is progressive neurological deficit in a patient with an epidermoid. The combination of subtotal resection, external-beam radiotherapy, and stereotactic radiosurgery may be useful for local tumor control but the long-term prognosis is guarded.     

Spinal arachnoid cysts associated with syringomyelia: report of two cases and a review of the literature

We describe two cases of spinal arachnoid cyst associated with syringomyelia and report the clinical results after surgical treatment using excision of the cyst without a shunt operation for the syringomyelia. Case 1 is a 73-year-old woman who presented with a spastic gait and numbness of her bilateral lower extremities. Magnetic resonance imaging (MRI) showed the presence of a spinal arachnoid cyst extending from T3 to T8 and syringomyelia from T8 to T10. The cyst had compressed the spinal cord anteriorly. We excised the cyst without applying a shunt tube for the syringomyelia. Case 2 is a 68-year-old woman who presented with gait disturbance and numbness of her left lower extremity. MRI indicated that the spinal cord had been compressed anteriorly by a spinal arachnoid cyst extending from T10 to T11. Syringomyelia existed just caudal to the cyst at T11. In our surgical treatment, we excised only the cyst. In both cases, neurologic examination after the operation showed amelioration of the condition. Postoperative MRI indicated that the spinal cord had moved to the center, its original position, and the syringomyelia had decreased in size. Conclusively, spinal arachnoid cyst associated with syringomyelia can be treated by simple excision of the cyst without shunting the syrinx if the decompression effect resulting from removal of the cyst is sufficient.     

Intradiploic arachnoid cyst identified by diffusion-weighted magnetic resonance imaging--case report

A 72-year-old woman presented with an intradiploic arachnoid cyst in the occipital intradiploic space which was found incidentally by magnetic resonance (MR) imaging. Computed tomography revealed a widened diploic space and thinning of the inner and outer tables of the occipital bone. The cyst appeared as isointense to the cerebrospinal fluid on both T1- and T2-weighted images. The differential diagnosis of intradiploic epidermoid cyst could be excluded because the lesion was low intensity on diffusion-weighted MR images. Arachnoid cyst is a benign lesion, so exploratory surgery should be avoided unless the cyst is symptomatic. Diffusion-weighted MR imaging is an effective modality to distinguish diploic epidermoid cysts from arachnoid cysts.     

Endoscopic treatment of prepontine arachnoid cysts

Prepontine (or suprasellar) arachnoid cysts are uncommon in clinical practice and experience in their management may therefore be limited. Symptomatic cysts usually present with features of hydrocephalus due to obstruction of the third ventricle and aqueduct, and occlusion or partial obstruction of both foramina of Monro. Several treatment techniques have been used including stereotactic aspiration, microsurgical excision and shunting, but the best method of treatment remains unclear and the role of endoscopy is not yet established. We report our experience in a series of seven patients who had endoscopic treatment for prepontine arachnoid cysts; five were children under 15 years old who presented with delayed development and/or enlarged heads. The two adult patients, both of whom had insertion of shunts as children, presented with headache and vomiting due to shunt blockage. All patients improved following endoscopic cyst fenestration. There was no operative morbidity and there have been no relapses to date. Endoscopic fenestration of prepontine arachnoid cysts appears to be an effective method of treatment.     

Linear accelerator radiosurgery for vestibular schwannoma: measuring tumor volume changes on serial three-dimensional spoiled gradient-echo magnetic resonance images

OBJECT: The authors report on a series of 46 patients harboring vestibular schwannomas (VSs) treated using linear accelerator (LINAC) radiosurgery and an analysis of serial magnetic resonance (MR) imaging data, specifically the changes in tumor volume. METHODS: Fifty-three consecutive patients underwent LINAC radiosurgery for VS between 1993 and 2002. Seven of these patients were lost to follow up. Three-dimensional (3D) spoiled gradient-echo (SPGR) MR imaging was performed at 3- to 4-month intervals after radiosurgery. Tumor volume was measured on Gd-enhanced MR images of each slice. The median duration of follow-up MR imaging studies was 56.5 months (range 12-120 months). Follow-up imaging studies were conducted for longer than 1 year in 42 of 53 patients. Tumor volume changes were categorized into four types: enlargement (eight lesions [19%]), no change (two lesions [4.8%]), transient enlargement followed by shrinkage (19 lesions [45.2%]), and direct shrinkage (13 lesions [31%]). Two cases (4.8%) with twice the initial tumor volume required repeated radiosurgery. All cases of transient enlargement had subsequent shrinkage within 2 years after radiosurgery. Nine (21.4%) of 42 patients demonstrated ventricular enlargement on MR images obtained after radiosurgery. Three patients (7.1%) required placement of a ventriculoperitoneal shunt because of symptomatic hydrocephalus, and another four cases (9.5%) spontaneously resolved. CONCLUSIONS: Volume measurement on 3D-SPGR MR imaging was a suitable method to assess tumor changes. Volume changes beyond twofold or continuous enlargement for longer than 2 years after radiosurgery are key criteria in rating the effects of radiation. Some cases of hydrocephalus after radiosurgery resolved spontaneously and their rates of occurrence were similar to the typical incidence of hydrocephalus associated with VS.     

Stereotactic radiosurgery for pituitary adenomas: an intermediate review of its safety, efficacy, and role in the neurosurgical treatment armamentarium

OBJECT: Pituitary adenomas are very common neoplasms, constituting between 10 and 20% of all primary brain tumors. Historically, the treatment armamentarium for pituitary adenomas has included medical management, microsurgery, and fractionated radiotherapy. More recently, radiosurgery has emerged as a viable treatment option. The goal of this research was to define more fully the efficacy, safety, and role of radiosurgery in the treatment of pituitary adenomas. METHODS: Medical literature databases were searched for articles pertaining to pituitary adenomas and stereotactic radiosurgery. Each study was examined to determine the number of patients, radiosurgical parameters (for example, maximal dose and tumor margin dose), duration of follow-up review, tumor growth control rate, complications, and rate of hormone normalization in the case of functioning adenomas. A total of 35 peer-reviewed studies involving 1621 patients were examined. Radiosurgery resulted in the control of tumor size in approximately 90% of treated patients. The reported rates of hormone normalization for functioning adenomas varied substantially. This was due in part to widespread differences in endocrinological criteria used for the postradiosurgical assessment. The risks of hypopituitarism, radiation-induced neoplasia, and cerebral vasculopathy associated with radiosurgery appeared lower than those for fractionated radiation therapy. Nevertheless, further observation will be required to understand the true probabilities. The incidence of other serious complications following radiosurgery was quite low. CONCLUSIONS: Although microsurgery remains the primary treatment modality in most cases, stereotactic radiosurgery offers both safe and effective treatment for recurrent or residual pituitary adenomas. In rare instances, radiosurgery may be the best initial treatment for patients with pituitary adenomas. Further refinements in the radiosurgical technique will likely lead to improved outcomes.     

Integration of the metabolic data of positron emission tomography in the dosimetry planning of radiosurgery with the gamma knife: early experience with brain tumors. Technical note

The purpose of this study was to assess the use of positron emission tomography (PET) as a stereotactic planning modality for gamma knife radiosurgery (GKS). The authors developed and validated a technique for fiducial marker imaging, importation, and handling of PET data for integration into GammaPlan planning software. The clinical feasibility in applying this approach to a selected group of patients presenting with recurrent glial tumors or metastases was evaluated. Positron emission tomography data can be integrated into GammaPlan, allowing a high spatial accuracy, as validated using a phantom. Positron emission tomography data were successfully combined with magnetic resonance (MR) images to define the target volume for the radiosurgical treatment of patients with recurrent glioma or metastasis. This approach may contribute to optimizing target selection for infiltrating or ill-defined brain lesions. Because PET is also useful for the pretreatment and follow-up evaluation, the use of stereotactic PET in these patients can enable an accurate comparison of PET-based metabolic data with MR-based anatomical data. This could give a better understanding of the metabolic changes following radiosurgery. The ability to use PET data in GKS represents a crucial step toward further developments in radiosurgery, as this approach provides additional information that may open new perspectives for the optimization of the treatment of brain tumors.     

Stereotactic cyst/ventricular-peritoneal shunting for the treatment of prepontine arachnoid cyst: case report

BACKGROUND: Prepontine (suprasellar) arachnoid cysts are uncommon in clinical practice, so experiences in their management are limited and the best method of treatment for them remains unclear. Here we report our experience in using stereotactic cyst/ventricular-peritoneal shunting for the treatment of prepontine arachnoid cyst. CASE DESCRIPTION: A 42-year-old woman with prepontine arachnoid cyst was treated with cyst/ventricular-peritoneal shunting: the ventricular catheter was precisely inserted at a point where it could drain from the cyst and the ventricle at the same time. The postoperation CT scan showed that the cyst and the enlarged ventricle shrunk markedly. During a 1-year follow-up period, she remained symptom-free and had returned to full-time work. CONCLUSION: Stereotactic cyst/ventricular-peritoneal shunting appears to be an effective method for treating prepontine arachnoid cyst.     

Stereotactic radiosurgery for cavernous malformations

OBJECT: The use of stereotactic radiosurgery to treat cerebral cavernous malformations (CMs) is controversial. To evaluate the efficacy and safety of CM radiosurgery, the authors reviewed the experience at the Mayo Clinic during the past 10 years. METHODS: Seventeen patients underwent radiosurgery for high-surgical-risk CMs in the following sites: thalamus/basal ganglia (four patients), brainstem (12 patients), and corpus callosum (one patient). All patients had experienced at least two documented hemorrhages before undergoing radiosurgery. Stereotactic magnetic resonance (MR) imaging was used for target localization in all cases. The median margin radiation dose was 18 Gy and the median maximum dose was 32 Gy. The median length of follow-up review following radiosurgery was 51 months. The annual hemorrhage rate during the 51 months preceding radiosurgery was 40.1%, compared with 8.8% in the first 2 years following radiosurgery and 2.9% thereafter. In 10 patients (59%) new neurological deficits developed that were associated with regions of increased signal on long-repetition time MR imaging performed a median of 8 months (range 5-16 months) after radiosurgery. Three patients recovered, giving the group a permanent radiation-related morbidity rate of 41%. Compared with 31 patients harboring arteriovenous malformations (AVMs) of sizes and in locations similar to those of the aforementioned CMs, who underwent radiosurgery during the same time period, the patients with CMs were more likely to experience radiation-related complications (any complication, 59% compared with 10%; p < 0.001; permanent complication, 41% compared with 10%; p = 0.02). CONCLUSIONS: It is impossible to conclude that radiosurgery protects patients with CMs against future hemorrhage risk based on the available data, although it appears that some reduction in the bleeding rate occurs after a latency interval of several years. The risk of radiation-related complications after radiosurgery to treat CMs is greater than that found after radiosurgery in AVMs, even when adjusting for lesion size and location and for radiation dose.     

Atypical Cerebellar Slump Syndrome and External Hydrocephalus following Craniocervical Decompression for Chiari I Malformation: Case Report

Symptomatic cerebellar slump (CS) and external hydrocephalus (EH) are amongst the rarer complications of foramen magnum decompression (FMD) for Chiari I malformation (CM). CS typically presents with delayed onset headache related to dural traction or with neurological deficit offsetting the benefit of FMD. EH, consisting of ventriculomegaly along with subdural fluid collection(s) (SFCs), has been related to cerebrospinal fluid egress from a tiny breach in an otherwise intact arachnoid. We describe the case of a 21-year-old man with CM and syringomyelia who presented with impaired gag, spastic quadriparesis, and raised intracranial pressure 1 week following an uneventful FMD during which the arachnoid had been widely fenestrated. Magnetic resonance imaging (MRI) showed an infratentorial SFC, dilated aqueduct and triventriculomegaly, features of CS, and a residual but resolving syrinx. His symptoms resolved following a high pressure ventriculo-peritoneal shunt. At a 6-month follow-up visit, he was asymptomatic and demonstrated partial resolution of the syrinx, with no recurrence of the SFC. The unusual features in the clinical course of this patient were an atypical CS syndrome presenting with concomitantly resolving syringomyelia, and the development of EH after a wide arachnoidal fenestration. This is the first case in indexed literature describing such a combination of unusual postoperative complications of a FMD. A hypothesis is presented to explain the clinico-radiological findings of the case.     

Primary central nervous system lymphoma of the brain stem responding favorably to radiosurgery: a case report and literature review

OBJECTIVE: To explore various therapeutic alternatives and evaluate the clinical results of patients with primary central nervous system lymphoma (PCNSL). We report a case of PCNSL with involvement of the brain stem managed with radiosurgery using the Leksell gamma knife as the treatment modality. CASE DESCRIPTION: A 55-year-old white woman presented with complaints of weakness on the left side of her body and double vision associated with a frontal headache. Nervous system examination revealed right-sided oculomotor palsy and left-sided motor paresis, grade 2/5, in both upper and lower limbs. Her Karnofsky performance score was 50. A contrast-enhanced magnetic resonance imaging scan of the brain revealed an irregular space-occupying lesion in the pons that enhanced uniformly with gadolinium. A frame-based stereotactic biopsy was performed revealing a B-cell malignant lymphoma. Subsequently, stereotactic radiosurgery using the Leksell gamma knife was performed. A dose of 11 Gy was delivered to the tumor margin. A follow-up magnetic resonance imaging scan after 2 months revealed a 50% reduction in the size of the enhancing lesion. CONCLUSION: Our own results and limited evidence from the literature suggest stereotactic radiosurgery as a potentially safe and effective treatment option in patients with PCNSL.     

Minimally invasive management of the third ventricle glioma in a patient without hydrocephalus: neurofiberscopic biopsy followed by gamma knife radiosurgery.

There is usually concern that ventricular enlargement is necessary for safe neuroendoscopic procedures. However, newly developed models of neurofiberscopes with a small outer diameter can be effectively used even in patients without ventriculomegaly. We present the case of a successful neurofiberscopic biopsy of a third ventricle anaplastic astrocytoma in a previously shunted patient without hydrocephalus. Subsequent gamma knife radiosurgery led to complete disappearance of the tumor. It seems that presence of collapsed ventricles, and even symptoms consistent with the slit ventricle syndrome, should not be considered as contraindications for neurofiberscopic surgery when brain compliance is sufficiently preserved. The latter should be considered as the key point of safe endoscopic manipulations. The combination of the neuroendoscopy and stereotactic radiosurgery provides wide possibilities for minimally invasive management of selected intracranial tumors.     

Arachnoid cyst of the craniocervical junction: case report.

OBJECTIVE AND IMPORTANCE: An arachnoid cyst at the craniocervical junction presenting with obstructive hydrocephalus as a result of blockage of the outflow of the fourth ventricle is described. This is a very rare anatomic site, with only five other cases described in the literature. CLINICAL PRESENTATION: A 37-year-old woman presented with a 9-month history of severe neck pain, persistent vomiting, visual disturbances, and numbness of the nose, cheek, and lips. She had severe bilateral papilledema on ophthalmoscopy. Magnetic resonance imaging revealed a midline cystic lesion extending down to C2. INTERVENTION: The patient underwent posterior fossa craniectomy and excision of the arachnoid cyst. She made a full recovery and was asymptomatic at follow-up examination. CONCLUSION: The symptomatology of these rare craniocervical arachnoid cysts and their development are discussed.     

Seven years of clinical experience with the programmable Codman Hakim valve: a retrospective study of 583 patients

OBJECT: The goal of this study was to assess the value of the Codman Hakim programmable valve to settings in the range of 30 to 200 mm H2O. This valve can be adjusted noninvasively for cerebrospinal fluid (CSF) drainage. METHODS: The authors conducted a single-center retrospective study of 583 patients (421 adults and 162 children) suffering from hydrocephalus of various causes (379 patients), normal-pressure hydrocephalus (174 patients), arachnoid cyst (14 patients), and pseudotumor cerebri (16 patients). In all cases a Codman Hakim programmable valve was implanted; in 82.8% of cases it was included during the patient's first shunt implantation. In 42.4% of the cases valve pressure adjustment was required at least once (mean number of adjustments 1.2, maximum 23). The patients' clinical status improved after 64.6% of pressure adjustments. Accidental resetting of opening pressure, other than that caused by magnetic resonance (MR) imaging, was uncommon. Because MR imaging caused resetting in 26.8% of cases in which it was used, it was deemed mandatory to obtain an x-ray film after MR imaging. Valve malfunction, blockage, or adjustment difficulties occurred in 2% of valves implanted, and nontraumatic subdural fluid collections were demonstrated in 5.1% of patients (13 of whom were treated by valve pressure adjustment alone). Five-year shunt survival was 53.1% for first-time shunt implantations. The shunt infection rate was 8.5% of valve implantations. Catheter-related complications and shunt-related infections were the main reasons for surgical revision and the major cause of shunt failure. At follow-up review, 97% of children and 90% of adults had improved. CONCLUSIONS: Because one cannot know in advance which case will turn out to be complicated, the authors' preference is to use the Codman Hakim programmable valve for all conditions in which CSF should be drained.     

Stereotactic radiosurgery for well-circumscribed fibrillary grade II astrocytomas: an initial experience

OBJECTIVE: To examine the role of stereotactic radiosurgery in the management of patients with progressive, well-circumscribed grade II fibrillary astrocytomas. METHODS: During a 13-year interval, 12 patients (median age: 25 years) required multimodality management for recurrent or unresectable World Health Organization (WHO) grade II fibrillary astrocytomas. Tumors involved the brainstem (n = 4), thalamus (n = 1), cerebellum (n = 1), frontal lobe (n = 4), temporal lobe (n = 1), and parietal lobe (n = 1). Diagnosis was confirmed by stereotactic biopsy (n = 5), partial resection (n = 5), and near total resection (n = 2). Multimodality management of patients prior to radiosurgery included fractionated radiation therapy (n = 4), stereotactic cyst drainage (n = 1), and ventriculoperitoneal shunt placement (n = 2). Tumor volumes varied from 1.2 to 45.1 cm(3). The median radiosurgical dose to the tumor margin was 16 Gy. RESULTS: After radiosurgery, serial imaging showed complete tumor resolution in 1 patient, reduced tumor volume in 4, stable tumor volume in 3, and delayed tumor progression in 4 (3 patients with increase in cyst size only). Therapy after radiosurgery included additional cytoreductive surgery (n = 1) for recurrence of a higher grade tumor, stereotactic cyst aspiration (n = 1), and stereotactic intracavitary irradiation (n = 1). All patients were alive at a median follow-up of 52 months after radiosurgery and 103 months after diagnosis. In 8 patients, follow-up lasted more than 60 months. CONCLUSION: Stereotactic radiosurgery is a potential alternative or adjunctive strategy in the management of selected patients with WHO grade II fibrillary astrocytomas.