Gamma knife radiosurgery for trigeminal neuralgia: the initial experience of The Barrow Neurological Institute.

PURPOSE: To assess the efficacy and complications of Gamma Knife radiosurgery for trigeminal neuralgia. METHODS AND MATERIALS: The Barrow Neurological Institute (BNI) Gamma Knife facility has been operational since March 17, 1997. A total of 557 patients have been treated, 89 for trigeminal neuralgia (TN). This report includes the first 54 TN patients with follow-up exceeding 3 months. Patients were treated with Gamma Knife stereotactic radiosurgery (RS) in uniform fashion according to two sequential protocols. The first 41 patients received 35 Gy prescribed to the 50% isodose via a single 4-mm isocenter targeting the ipsilateral trigeminal nerve adjacent to the pons. The dose was increased to 40 Gy for the remaining 13 patients; however, the other parameters were unvaried. Outcome was evaluated by each patient using a standardized questionnaire. Pain before and after RS was scored as level I-IV per our newly-developed BNI pain intensity scoring criteria (I: no pain; II: occasional pain, not requiring medication; III: some pain, controlled with medication; IV: some pain, not controlled with medication; V: severe pain/no pain relief). Complications, limited to mild facial numbness, were similarly graded by a BNI scoring system. RESULTS: Among our 54 TN patients, 52 experienced pain relief, BNI score I in 19 (35%), II in 3 (6%), III in 26 (48%), and IV in 4 (7%). Two patients (4%) reported no relief (BNI score V). Median follow-up was 12 months (range 3-28). Median time to onset of pain relief was 15 days (range 0-192), and to maximal relief 63 days (range 0-253). Seventeen (31%) noted immediate improvement (

Gamma knife radiosurgery for trigeminal neuralgia: experience at the Barrow Neurological Institute.

Forty-three patients with trigeminal neuralgia (TN) unresponsive to pharmacologic treatment and/or prior invasive procedures underwent stereotactic radiosurgery with the Gamma Knife (GK). Outcome was evaluated by a standardized questionnaire mailed to each patient. The mean follow-up was 9 months. Fifteen patients (35%) reported no trigeminal pain and were no longer taking medication. Three patients (7%) experienced occasional pain, but were no longer taking medication. In 15 patients (35%), pain improved and was adequately controlled by medication, often in lower dosages than preoperatively. Pain was reduced in 9 patients (21%), but their symptoms were still inadequately controlled by drug therapy, and 1 patient (2%) reported no pain relief after treatment. Three patients (7%) described new facial numbness, but in none was this bothersome. GK radiosurgery for TN appears to have minimal morbidity, although the success rate may be slightly lower than that of other operative procedures. More patients and longer follow-up are needed before drawing final conclusions regarding efficacy and complications.

Transient resolution of bilateral tremor after unilateral thalamotomy, associated with focal injury of the corpus callosum: case report.

We present a patient with Parkinson's disease whose bilateral tremor transiently resolved after a unilateral left ventrolateral thalamotomy. The transient resolution of the bilateral tremor was associated with a focal thalamic lesion and a second lesion in the corpus callosum. The mechanism of this phenomenon may be related to temporary disruption of descending bilateral corticostriate projections by the callosal lesion.

Novel heuristics of functional neural networks: implications for future strategies in functional neurosurgery.

A hypothesis is proposed that (a) the skeletomotor basal ganglia-thalamocortical loop functions as a model of the behavior of the body and the environment, and that (b) dopaminergic neurons of the substantia nigra pars compacta comprise the substrates of an error distribution system projecting to the striatum. This error signal initiates the learning process in the basal ganglia - learning starts with increasing intensity of the error signal and is complete when the signal is minimized. Parkinson's disease (PD) may be considered as a disruption of learning processes in the basal ganglia that results from progressive degeneration of the substrate that is the error distribution system for this functional motor loop. Numerous clinical and experimental observations obtained from functional procedures for PD that show identical clinical effects in alleviating parkinsonian symptoms, e.g. thermocoagulative lesions and chronic stimulation, can be explained through the use of this conceptual theory of basal ganglia function. Because any controlling neural network must possess a model of the behavior of its controlled object, the heuristics outlined in this theory are broadly applicable for explaining the function of the nervous system, as well as being useful for planning surgical procedures and future strategies in functional neurosurgery.

Intrathecal baclofen for intractable spasticity of spinal origin: results of a long-term multicenter study.

A total of 93 patients with intractable spasticity due to either spinal cord injury (59 cases), multiple sclerosis (31 cases), or other spinal pathology (three cases) were entered into a randomized double-blind placebo-controlled screening protocol of intrathecal baclofen test injections. Of the 88 patients who responded to an intrathecal bolus of 50, 75, or 100 micrograms of baclofen, 75 underwent implantation of a programmable pump system for chronic therapy. Patients were followed for 5 to 41 months after surgery (mean 19 months). No deaths or new permanent neurological deficits occurred as a result of surgery or chronic intrathecal baclofen administration. Rigidity was reduced from a mean preoperative Ashworth scale score of 3.9 to a mean postoperative score of 1.7. Muscle spasms were reduced from a mean preoperative score of 3.1 (on a four-point scale) to a mean postoperative score of 1.0. Although the dose of intrathecal baclofen required to control spasticity increased with time, drug tolerance was not a limiting factor in this study. Only one patient withdrew from the study because of a late surgical complication (pump pocket infection). Another patient received an intrathecal baclofen overdose because of a human error in programming the pump. The results of this study indicate that intrathecal baclofen infusion can be safe and effective for the long-term treatment of intractable spasticity in patients with spinal cord injury or multiple sclerosis.

Cortical biopsy in Alzheimer's disease: diagnostic accuracy and neurochemical, neuropathological, and cognitive correlations. Intraventricular Bethanecol Study Group.

Neurochemical assessments were performed on biopsy samples taken from the right frontal lobe of patients diagnosed with Alzheimer's disease (AD), before the implantation of a ventricular catheter and pump assembly for the infusion of bethanechol chloride as an experimental therapy. The pathologically diagnosed patients with AD (n = 35; mean age, 67 +/- 1.5 yr) were compared with a group of samples from normal age-equivalent autopsied controls (n = 22; mean age, 68 +/- 2 yr) and autopsied AD brains (n = 11; mean age, 73 +/- 2 yr). Samples were assayed for choline acetyltransferase (ChAT), acetylcholinesterase, binding to [3H]quinuclidinyl benzilate as an index of total muscarinic cholinergic binding, and [3H]pirenzepine binding as an index of M1 cholinergic receptor subtype binding. Mean levels of ChAT activity were decreased in the biopsied patients to 36% of age-matched autopsied controls. The loss of ChAT activity correlated significantly with the Mini-Mental State Examination, an index of global cognitive function. Mean ChAT activity in autopsied AD cortex was further decreased compared with controls, indicating continuous decline through the course of the disease. Acetylcholinesterase followed a similar, less dramatic decline. No differences were found in [3H]quinuclidinyl benzilate binding or [3H]pirenzepine binding between biopsied and autopsied controls. Neuritic plaque counts did not correlate with either the Mini-Mental State Examination or ChAT activity in the biopsy specimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Iatrogenic arteriovenous fistula presenting as a recurrent subdural hematoma. Case report.

An unusual case of an iatrogenic dural arteriovenous fistula is reported. The patient presented with a history of progressive generalized headache over a period of 3 to 4 weeks. Computerized tomography demonstrated a chronic subdural hematoma that was successfully evacuated by burr-hole drainage. The patient's postoperative course was complicated by recurrent acute subdural hematomas at the drainage site. Coagulation studies were unremarkable. Selective external carotid angiography demonstrated a small dural arteriovenous fistula adjacent to the burr hole used for the initial operative procedure. Extension of the bone flap and coagulation of the fistula resulted in a good outcome. In the patient with recurrent acute subdural hematoma, the possibility of a vascular malformation must be considered. Selective internal and external carotid angiography is key to the correct diagnosis.

Intracerebroventricular bethanechol chloride infusion in Alzheimer's disease. Results of a collaborative double-blind study.

The use of intracerebroventricular bethanechol chloride infusion in patients with Alzheimer's disease was first reported in 1984. An initial trial in four patients demonstrated the feasibility of this approach for cholinergic drug delivery to the brain, but objective improvement in cognitive function was not documented. A collaborative placebo-controlled double-blind crossover study has now been carried out in 49 patients with biopsy-documented Alzheimer's disease. The results demonstrate a statistical improvement in Mini-Mental State scores and significantly slower performance on Trails A testing during drug infusion. Other neuropsychological test scores were not similarly affected. The degree of improvement was not sufficient to justify further treatment of Alzheimer's disease patients by intracerebroventricular infusion of bethanechol chloride. The drug delivery system used in the study was well tolerated, with two irreversible complications in more than 50,000 patient days.

Administration of intraspinal morphine sulfate for the treatment of intractable cancer pain.

A total of 24 patients with intractable cancer pain were evaluated as candidates for spinal morphine therapy. Temporary trials were carried out with bolus injections of preservative-free morphine sulfate via percutaneously inserted epidural catheters. Fourteen patients felt that pain relief was sufficient to warrant long term morphine application, and permanent drug delivery systems were implanted. These consisted of an Ommaya reservoir and an epidural spinal catheter in 6 patients and an Infusaid pump with either an epidural or subarachnoid spinal catheter in 8 patients. Pain relief with these systems was felt to be excellent in 7 patients, good in 4 patients, and fair in 3 patients. There was a statistically significant reduction in supplemental narcotic use between the pre- and postoperative periods (P less than 0.001). Median survival after operation was 3.0 months (mean, 5.0 months), with a range of 1 to 23 months. Tolerance was seen in all patients regardless of the mode of drug delivery, but it occurred more quickly with bolus injections than with continuous infusion (statistically significant difference, P less than 0.05). A persistent cerebrospinal fluid fistula developed in 1 patient; this required wound revision. No other serious complications or episodes of respiratory depression occurred. We conclude that intraspinal morphine sulfate is a beneficial treatment option for cancer patients in whom pain has become debilitating and unresponsive to oral or parenteral narcotic regimes.

Comparative study of rat sciatic nerve microepineurial anastomoses made with carbon dioxide laser and suture techniques: Part 2. A morphometric analysis of myelinated nerve fibers.

Sciatic nerves of rats were severed with steel scalpel blades and subsequently anastomosed with epineurial sutures and laser-aided techniques. Morphometric analysis of myelinated nerve fibers proximal and distal to the anastomosed region revealed that the laser had no deleterious effects on the degree of retrograde axonal degeneration or regeneration potential as compared to the traditional suture technique. Although no significant difference in myelinated nerve fiber population was evident between the two methods, future experimentation with various laser parameters might lead to more effective use of lasers in nerve repair.

Postoperative neurological deficits may occur despite unchanged intraoperative somatosensory evoked potentials.

We describe 6 patients who demonstrated postoperative neurological deficits despite unchanged somatosensory evoked potentials during intraoperative monitoring. Although there is both experimental and clinical evidence that somatosensory evoked potentials are sensitive to some types of intraoperative mishap, the technique should be employed with an awareness of its possible limitations.

Comparative study of microepineurial anastomoses with the use of CO2 laser and suture techniques in rat sciatic nerves: Part 1. Surgical technique, nerve action potentials, and morphological studies.

The possibility of utilizing the CO2 laser for neural anastomoses was investigated in a rat sciatic nerve model. One nerve in each animal was acutely divided and anastomosed using 10-0 nylon epineurial sutures, while the opposite side was joined by "welding" the opposed nerve ends together with CO2 laser pulses. The surgical incisions were reexplored 60 days postoperatively, action potentials were recorded across the anastomoses, and the nerves were removed for light and electron microscopy. The operative patency rate in the suture group was 100%, compared to 87% in the laser group. Among those animals with bilaterally intact nerves, action potentials could be recorded across the anastomotic site in 78% of the sutured preparations and in 85% of nerves spot-welded with the CO2 laser. Morphological studies showed a greater degree of scar tissue formation and constriction in the anastomotic zone of the nerves joined by sutures than was present in laser-treated animals. We believe these preliminary observations suggest that the CO2 laser may have a role to play in peripheral nerve surgery. Further study of this technique is warranted.

Postoperative paraplegia with preserved intraoperative somatosensory evoked potentials. Case report.

Intraoperative somatosensory evoked potentials (SSEP's) are being used with increasing frequency to monitor neurological function during spinal surgery. The authors report a case of postoperative paraplegia that occurred despite preserved intraoperative SSEP's in an achondroplastic dwarf who underwent correction of a congenital kyphoscoliosis. Surgeons and anesthesiologists involved with SSEP monitoring should be aware that false-negative results may occur with this technique.

Computed tomography in cases of coccidioidal meningitis, with clinical correlation.

Cranial computed tomographic (CT) scans of 22 patients with coccidioidal meningitis were reviewed and their clinical course was analyzed. Abnormalities of the ventricular system or the basilar cisterns or both were present in 16 instances. Although it is not a definitive diagnostic tool, the CT scan is helpful in suggesting a diagnosis of coccidioidal meningitis and in predicting the prognosis of patients affected by the disease.

Use of the Brown-Roberts-Wells stereotactic frame for functional neurosurgery.

The Brown-Roberts-Wells (BRW) stereotactic unit has proven itself to be a highly accurate instrument for biopsying or locating pathologic intracranial lesions based on CT scan information. We utilized the BRW frame to select 18 target sites in 12 patients undergoing functional stereotactic procedures. Two patients had bilateral cingulumotomies, 5 had thalamotomies for movement disorders, and 5 underwent electrode implantations for the treatment of chronic pain. Stereotactic frame settings were determined using a positive contrast ventriculogram, orthogonal radiographs, and a computer program provided with the BRW system. In addition, attempts were made to select targets based on CT scan landmarks alone, and these were compared to those derived using ventriculography. We found the BRW frame to be a satisfactory device for performing functional neurosurgical procedures based on ventriculographic landmarks. Coordinates derived from CT scans were similar to those obtained with ventriculography, but were not accurate enough to permit the use of CT scanning as the sole means of target identification. Although future improvements in imaging techniques and computer software are likely to occur, our experience supports ventriculography as the current method of choice for the precise localization of functional targets with the BRW stereotactic system.

Chronic spinal epidural hematoma presenting as lumbar stenosis: clinical, myelographic, and computed tomographic features. A case report.

The case of a patient with a chronic spinal epidural hematoma presenting as lumbar stenosis is described. There was no history of major trauma to the lumbar spine, anticoagulant use, or coagulopathy. The clinical, myelographic, and CT findings are presented and discussed.