Applied neurophysiology最新文献

The Nucleus 22-channel implantable hearing prosthesis (Cochlear Pty. Ltd., Lane Cove, Sydney, Australia) has been modified by computer programming (MOCO, Inc., Scituate, Mass. USA) into a functional electrical stimulator. Individual or multiple channels can be sequenced and adjusted for their amplitude, width and frequency of the pulse so that activation of single and multiple nerves can be achieved. Sciatic nerve branches (lateral and medial) of anesthetized rabbits were stimulated to produce single contractions or co-contraction at the ankle and simultaneous bilateral joint movements. The spiral (Helix) electrode was also found suitable in these experiments. The external equipment is being re-designed for a wearable ambulation unit to be used in paraplegic subjects.

A definitive pathoanatomic diagnosis was achieved in 14 biopsies of deep cerebral tumors in which the Laitinen CT adapter was utilized. In 5 patients, a third-ventricular colloid cyst was aspirated or resected by stereotactic endoscopy, with excellent results after a mean follow-up time of 2.5 years. Several instruments, including a diagnostic ultrasound probe, an ultrasonic aspirator, a combination laser and an endoscope can be used stereotactically when mounted on a special instrument carrier. Integration of the Laitinen stereotactic device and the CT adapter was developed to allow noninvasive stereotactic radiotherapy in a conventional fractionation schedule by a standard linear accelerator. Technical experiences using this radiosurgical system in over 30 sessions for treating inoperable cerebral arteriovenous malformations are promising, but the follow-up time is too short for evaluating the clinical effect.

Depression was evaluated in 10 patients before and after therapeutic mesothalamic brain stimulation for chronic pain. Minnesota multiphasic personality inventory T scores for depression were high in all patients before stimulation. Scores were decreased in 8 of 10 patients with chronic deep brain stimulation, three of whom returned to normal. Pain relief was good to excellent in 9 of 10 patients. It is concluded that depression is secondary to pain or pain-inducing factors which implicate the catecholamine and serotonergic systems.

We analyzed the prognostic significance of tumor histology, location, treatment, and selected clinical features at presentation in 91 consecutive patients with malignant gliomas diagnosed by stereotactic biopsy. In 64 patients with glioblastoma multiforme (GBM) the following factors were associated with longer survival: lobar tumor location, adequate radiation therapy (RT) tumor dose 5,000-6,000 cGy, Karnofsky performance rating (KPR) at presentation greater than or equal to 70, and a normal level of consciousness before biopsy. In 27 patients with anaplastic astrocytoma, factors associated with longer survival were lobar tumor location, adequate RT, age less than 40 years at presentation, and a history of seizures. Delayed cytoreductive surgery in lobar GBM extended median survival but did not improve long-term survival. For patients with deep or midline malignant gliomas and for selected patients with lobar tumors, stereotactic biopsy followed by RT may be the most reasonable initial treatment strategy.

Three-dimensional information obtained with neuroradiological exams performed under stereotactic conditions is displayed on a surgical console within the graphic reconstruction of the geometry of stereotactic frames. Planning of convenient probe trajectories can be carried out taking into account all data derived from different diagnostic techniques.

Early detection and precise diagnosis of presenile dementias are important since they determine subsequent medical care. Presently the only way to classify these syndromes is by neuropathological examination. Between 1972 and 1987, 222 stereotactic serial brain biopsies were performed in 25 selected demented patients. Comparison between preoperative clinical diagnosis and histological finding gives the following results: in 32% the clinical diagnosis has been confirmed, in 60% the diagnosis has been corrected or specified and in 8% the stereotactic brain biopsies only showed unspecific pathological gliosis.

Stereotactic interstitial brain implants deliver locally high radiation doses to treat malignant gliomas. Dose to the surrounding normal brain from an 125I implant has been compared with the dose from an external irradiation technique. Results show that an implant offers a higher dose gradient around the tumor and hence a lower dose to the normal brain. Moreover, some irregular-shaped tumors, while ideal for a stereotactic implant, may be very difficult to treat with external beams without delivering a significant radiation dose to the normal brain. An implant seems to be dosimetrically superior to external irradiation for delivering large tumor doses.

Long-term observation over 3-8 postoperative years of cases of Parkinson disease operated by stereotactic thalamotomy using a microelectrode recording technique is reported. The procedure is specifically useful in the following four groups: (1) tremor-dominant cases, (2) hemiparkinsonism, (3) cases with marked asymmetry in motor symptoms and (4) juvenile parkinsonism presenting levodopa-induced dyskinesia.

Local anesthesia is advocated for cortical mapping in certain neurological procedures. Occasionally, however, a modified general anesthetic is necessary. We describe a technique of balanced anesthesia in which the arm opposite to the craniotomy is selectively isolated from the effect of the neuromuscular blocking agent and hence preserves its motor response to cortical stimulation. The technique secures complete immobility of the patient during mapping of the brain, shortens the stimulation time, facilitates the localization of the motor cortex, precludes the development of full-blown seizures, increases safety and is well tolerated.