John F. Alksne

Intraoperative Assessment of Aneurysm Clip Placement by Intravenous Fluorescein Angiography

Clip occlusion of intracranial aneurysms can be difficult, and intraoperative misadventures are still fairly frequent. Many complications are caused by improper clip placement. Intraoperative conventional arteriography is time consuming and requires expensive image-intensifying equipment. As an alternative, we have found that the bolus intravenous administration of fluorescein produces the necessary intra-arterial dye concentration for the direct visualization of the perforating medium and large arteries in proximity to a clipped aneurysm. The technique is straightforward, requiring little additional operating time and an inexpensive set of disposable optical filters. No adverse reactions to fluorescein have been observed.

Idiopathic normal pressure hydrocephalus may be a “Two Hit” disease: Benign external hydrocephalus in infancy followed by deep white matter ischemia in late adulthood

To determine if normal pressure hydrocephalus (NPH) could result from decreased resorption of cerebrospinal fluid (CSF) by the arachnoidal villi, leading to benign external hydrocephalus [BEH] in infancy, followed by deep white matter ischemia (DWMI) in late adulthood (the more hydrophilic environment increasing resistance to CSF flow through the extracellular space (ECS) of the brain).

Single-Isocenter Frameless Intensity-Modulated Stereotactic Radiosurgery for Simultaneous Treatment of Multiple Brain Metastases: Clinical Experience

PURPOSE To describe our clinical experience using a unique single-isocenter technique for frameless intensity-modulated stereotactic radiosurgery (IM-SRS) to treat multiple brain metastases. METHODS AND MATERIALS Twenty-six patients with a median of 5 metastases (range, 2-13) underwent optically guided frameless IM-SRS using a single, centrally located isocenter. Median prescription dose was 18 Gy (range, 14-25). Follow-up magnetic resonance imaging (MRI) and clinical examination occurred every 2-4 months. RESULTS Median follow-up for all patients was 3.3 months (range, 0.2-21.3), with 20 of 26 patients (77%) followed up until their death. For the remaining 6 patients alive at the time of analysis, median follow-up was 14.6 months (range, 9.3-18.0). Total treatment time ranged from 9.0 to 38.9 minutes (median, 21.0). Actuarial 6- and 12-month overall survivals were 50% (95% confidence interval [C.I.], 31-70%) and 38% (95% C.I., 19-56%), respectively. Actuarial 6- and 12-month local control (LC) rates were 97% (95% C.I., 93-100%) and 83% (95% C.I., 71-96%), respectively. Tumors <or=1.5 cm had a better 6-month LC than those >1.5 cm (98% vs. 90%, p = 0.008). New intracranial metastatic disease occurring outside of the treatment volume was observed in 7 patients. Grade >or=3 toxicity occurred in 2 patients (8%). CONCLUSION Frameless IM-SRS using a single-isocenter approach for treating multiple intracranial metastases can produce clinical outcomes that compare favorably with those of conventional SRS in a much shorter treatment time (<40 minutes). Given its faster treatment time, this technique is appealing to both patients and personnel in busy clinics.

Frameless, real-time, surface imaging-guided radiosurgery: clinical outcomes for brain metastases.

Frameless stereotactic radiosurgery (SRS) for intracranial brain metastases can provide more comfortable treatment setup than rigid frame-based immobilization with equivalent accuracy. The aim of this study is to report the UCSD SRS experience and update the clinical outcomes using a novel real-time, frameless, surface imaging-guided (SIG-RS) technique in the treatment of brain metastases. Data were retrospectively examined for 163 patients totaling 490 lesions and 45 post-operative cavities treated with SIG- RS in a median delivery of 1 fraction (range, 1-5 fraction) and to a median dose of 22 Gy (range, 12-30 Gy). Local control and overall survival were estimated by the Kaplan-Meier method. Median follow-up for all patients was 6.7 months (range, 0.5-45.1 months), with 119 of 163 (73%) deceased at the time of analysis. The 134 patients (82%) with follow-up imaging studies totaling 378 lesions and 39 post-operative cavities were evaluated for local control. The actuarial 6- and 12-month local control was 90% (95% confidence interval (CI), 84-94%) and 79% (95% CI, 71-86%), respectively. The actuarial 6- and 12-month overall survival was 80% (95% CI, 74-85%) and 56% (95% CI, 49-63%), respectively. There is no significant difference in local control between treatment to post-operative cavities or intact lesions. Consistent with our earlier report of 44 patients, SIG-RS for treatment of intracranial metastases can produce outcomes comparable to those with conventional frame-based and frameless SRS techniques while providing greater patient comfort with an open-faced mask and fast treatment time.

Demonstration by magnetic resonance of symptomatic spinal epidural lipomatosis.

In patients with Cushings syndrome or morbid obesity, excessive accumulation of fat in the hips, upper back, abdomen, and mediastinum is well known (1, 3, 7). Excessive deposition of fat in the epidural space is less common, but must be recognized as a potential cause of neurological deficit (1-8). We report a patient with iatrogenic Cushings syndrome, in whom magnetic resonance imaging (MRI) established the specific diagnosis of spinal cord compression secondary to excess epidural fat.

Pathogenesis of Cerebral Vasospasm

Cerebral arteries have been shown to react to experimental subarachnoid hemorrhage with a nonspecific arterial injury reaction characterized by endothelial cell desquamation, adherence of platelets to the exposed collagen, subendothelial edema, and medial necrosis. This injury reaction is followed by a reparative process with intimal proliferation and medial fibrosis. We have postulated that the arterial narrowing seen by angiography in patients after subarachnoid hemorrhage may be a manifestation of this injury reaction. Because it is likely that the platelets adherent to the damaged endothelium play a major role in the propagation of the process, it is possible that therapy directed at preventing platelet accumulation may interrupt the cycle.

Neuropsychological change following gamma knife surgery in patients with left temporal lobe epilepsy: a review of three cases

Gamma knife surgery (GKS) is a radiation procedure recently used in the treatment of temporal lobe epilepsy (TLE). Preliminary studies have shown significant seizure reductions in patients 8-26 months postprocedure; however, little is known about the effect of GKS on cognitive functioning in TLE. We report neuropsychological data on three patients with left TLE and MRI evidence of hippocampal sclerosis who underwent GKS. Two models for assessing cognitive change, reliable change indices and regression-based norms for change, were used to measure preoperative versus 13- to 27-month postoperative cognitive change. Results revealed a significantly long delayed verbal memory decline on one measure following GKS. No patient declined on measures of IQ, visual memory, or language. Radiation-induced edema was present at the time of testing in all three patients, which may have affected verbal memory performance. While preliminary, these data suggest that GKS offers a less invasive option to anterior temporal lobectomy, but may produce neuropsychological changes similar to those produced by left anterior temperol lobectomy up to 2 years post-GKS treatment.

Intranasal schwannoma with extension into the intracranial compartment: case report

The authors present a case of intranasal schwannoma with extension into the intracranial compartment. Computed tomographic findings are presented, and a combined intranasal and subfrontal operative approach is described. The pathology, origin, and clinical characteristics of intranasal schwannomas are reviewed.

Pilocytic Astrocytoma Presenting as an Extra-axial Tumor in the Cerebellopontine Angle: Case Report

Glial tumors in the cerebellopontine angle (CPA) are rare. Four histologically distinct types of glial tumors of the CPA have been described in the literature as ependymoma, medulloblastoma, mixed glial tumor, and fibrillary astrocytoma. This case report describes a pilocytic astrocytoma of the CPA. A 58-year-old man with a hearing loss had an extra-axial tumor in the left CPA that extended into the internal auditory canal. The characteristics of the tumor on magnetic resonance imaging scans differed from those of typical CPA tumors. It adhered avidly to the cochlear and vestibular nerves, which had to be sacrificed for gross total resection. Microscopic examination showed the typical features of an adult-type pilocytic astrocytoma.

Modification of Experimental Post-Subarachnoid Hemorrhage Vasculopathy with Intracisternal Plasmin

Utilizing a double subarachnoid blood injection model in pigs, we have evaluated the protective effect of the intracisternal injection of the thrombolytic agent, plasmin, in preventing the secondary intracranial arteriopathy seen after artificial subarachnoid hemorrhage in untreated animals. Twelve animals injected with plasmin revealed markedly less intimal proliferation and medial necrosis than were seen in control animals. These observations support the hypothesis that the persistence of clotted blood around the intracranial arteries is the cause of the vasculopathy.