Prompt Recognition and Management of Postoperative Intracranial Hypotension-Associated Venous Congestion: A Case Report.

BACKGROUND: Postoperative intracranial hypotension-associated venous congestion (PIHV) is an uncommon cause of clinical deterioration after a neurosurgical procedure that is often unrecognized until late in its course. Functional outcomes range from remarkable neurological recovery to death. Little is understood about the reason for deterioration in certain patients compared with improvement in others. A 68-year-old man with a progressive cervical myelopathy underwent an uncomplicated cervical decompression and alignment restoration at our hospital and suffered violent generalized tonic-clonic seizures intraoperatively and postoperatively. A postoperative head CT showed a right parietal hematoma, but no other cranial findings. A subsequent MRI demonstrated what we describe as early PIHV with symmetric T2 signal changes in the bilateral deep gray structures. No diffusion restriction corresponded to these areas. A CT myelogram revealed a considerable CSF collection within the operative bed. Upon returning to the operating room to localize the source of the leak, a large dural tear was identified off of midline with a bone chip alongside the defect. The defect was repaired, and the patient remained comatose for over a week postoperatively. He made a remarkable gradual recovery, and after a month in the hospital and rehabilitation, he returned home with relatively minimal neurological deficits. CONCLUSIONS: We postulate that if caught early and treated aggressively, neurologic injury resulting from PIHV may be reversible despite initially ominous imaging. Neurosurgeons and neurointensivists should therefore be compelled to search for dural defects and return to the operating room for immediate repair.

Characterization of multiple sclerosis plaques using susceptibility-weighted imaging at 1.5 T: can perivenular localization improve specificity of imaging criteria?

BACKGROUND AND PURPOSE: The purpose of this study was to determine if magnetic resonance (MR) susceptibility-weighted imaging (SWI) can increase the conspicuity of corticomedullary veins within the white matter lesions of multiple sclerosis (MS) and, thus, aid in distinguishing plaques from leukoaraiosis. METHODS: We retrospectively reviewed MR examinations in 21 patients with a clinical diagnosis of MS and 18 patients with a clinical diagnosis of dementia. Examinations included fluid-attenuated inversion recovery (FLAIR) and SWI sequences obtained in the axial plane. Lesions greater than 5 mm in diameter on the axial FLAIR sequence were identified as periventricular or subcortical. Three neuroradiologists evaluated SWI images, compared with FLAIR, for a centrally located signal void in each lesion that was scored as present, absent, or indeterminate. RESULTS: In patients with MS, central veins were present in both periventricular lesions (75%, P < 0.001) and subcortical lesions (52%, P < 0.005). In patients with dementia, central veins were seen much less frequently in subcortical lesions (14%, P < 0.001); their association with periventricular lesions was not significant. CONCLUSIONS: Central veins were detected in MS lesions with a significantly greater frequency than that in patients with dementia. Susceptibility-weighted imaging increases the conspicuity of corticomedullary veins and may improve the specificity of MR findings in MS.

Arrested pneumatization of the skull base: imaging characteristics.

OBJECTIVE: Arrested skull base pneumatization is a benign developmental variant that can be confused with significant skull base disease processes. This study reviews the imaging findings in 30 suspected cases of arrested skull base pneumatization. CONCLUSION: When encountering a nonexpansile lesion with osteosclerotic borders, internal fat, and curvilinear calcifications in the basisphenoid bone or adjacent skull base, radiologists should strongly consider the diagnosis of arrested pneumatization.

Tumefactive cysts: a delayed complication following radiosurgery for cerebral arterial venous malformations.

We report five cases of symptomatic delayed cyst formation after radiosurgery for intracranial arterial venous malformations. Median time to discovery of the cysts following most recent radiosurgery was 59 months (range, 34-89 months). In all five patients, the radiation therapy-induced cysts exhibited tumefactive characteristics, including vasogenic edema, mass effect, and nodular enhancement. Despite these malignant features, these cystic lesions should be recognized as a benign complication of radiosurgery so that proper treatment (i.e., cystoperitoneal shunt surgery or excision) can be initiated.

Preangiographic evaluation of spinal dural arteriovenous fistulas with elliptic centric contrast-enhanced MR Angiography and effect on radiation dose and volume of iodinated contrast material.

BACKGROUND AND PURPOSE: The detection and localization of spinal dural arteriovenous fistulas (AVFs) remain diagnostic challenges. This study tested the hypothesis that elliptic centric contrast-enhanced MR angiography (MRA) can be used to detect spinal dural AVFs, predict the level of fistulas, and reduce the radiation dose and volume of iodinated contrast material associated with conventional angiography. METHODS: We examined 31 patients who presented with suspected spinal dural AVF between December 2000 and March 2004. All patients underwent MRA and conventional angiography. The effect of MRA on subsequent conventional angiography was assessed by analyzing total fluoroscopy time and volume of iodinated contrast material used. RESULTS: At angiography, spinal dural AVFs were diagnosed in 22 of 31 patients, and MRA depicted an AVF in 20 of the 22 patients. MRA findings correctly predicted a negative angiogram in seven of nine cases. Of the 20 true-positive MRA results, the level of the fistula was included in the imaging volume in 14. In 13 of these 14 cases, MRA results correctly predicted the side and the level of the fistula to within one vertebral level. Fluoroscopy time and the volume of contrast agent was reduced by more than 50% in the 13 patients with a spinal dural AVF in whom MRA prospectively indicated the correct level. CONCLUSION: Contrast-enhanced MRA can be used to detect spinal dural AVFs, predict the level of fistulas, and substantially reduce the radiation dose and volume of contrast agent associated with catheter spinal angiography.

Emergent, After Hours Magnetic Resonance Imaging of the Spine.

BACKGROUND AND PURPOSE: Requests for after-hours emergent spine MR imaging seem to be increasing. We sought to review the trend in after hours spine MRI utilization at our institution and to determine how these results impacted therapeutic intervention. METHODS: Following Institutional Review Board approval, reports from 179 after hours spinal MRI's performed over the past 13 years were obtained and the relevant electronic medical records were reviewed. RESULTS: Emergent after hours spine MRI utilization increased from 7 per year to 23 over 13 years. Fifty-eight percent (104/179) had significant findings. Twenty-nine percent (52/179) of all patients imaged underwent surgery to treat pathologies identified on MR. Surgery was performed in only 2% (4/179) of these patients within 3 hours and 6% (10/179) within 6 hours of MRI completion. Five percent (8/179) had findings that were treated with radiation therapy and in 78% of these it was performed within 6-12 hours. Of those in whom steroids or antibiotics were initiated, 41% and 50% were treated within 3 hours of MR scanning, respectively. DISCUSSION: Clinical use of emergent after hours spine MRI is steadily increasing at our institution. While MR imaging often discerned significant pathologies, performing these emergent studies rarely resulted in immediate surgical or radiotherapeutic intervention.

Melanoma brain metastases and vemurafenib: need for further investigation.

Brain metastases are a major cause of morbidity and mortality in patients with advanced melanoma. With the development of targeted agents for the treatment of metastatic melanoma, a great deal of interest has focused on whether selective BRAF inhibitors may play a role in the treatment of brain metastases in lieu of or in addition to surgery and/or radiation therapy. However, relatively little is known about the intracranial effectiveness of vemurafenib, the only US Food and Drug Administration-approved selective BRAF V600E inhibitor, because patients with brain metastases have historically been excluded from vemurafenib clinical trials. We describe 3 patients with BRAF V600E mutation metastatic melanoma in whom treatment with vemurafenib resulted in prompt extracranial disease response but progression of metastatic disease in the brain. Further, we discuss possible mechanisms responsible for the suboptimal central nervous system response observed in these patients and alternative therapies for patients with melanoma metastatic to the brain.