Applied neurophysiology最新文献

Preliminary experience with a newly constructed angiographic localizer system for use in stereotactic neurosurgery is reported. This localizer ring, mounted on the BRW head ring, allows for the transformation of target points with known stereotactic coordinates (e.g., visible on computerized tomography scans) onto angiograms, as well as the determination of stereotactic coordinates of a set of points (e.g., arteriovenous malformations) indicated on at least two angiograms.

Techniques for quantitatively describing the firing properties of neurons have been used to identify thalamic cells with a firing pattern which is correlated with EMG activity during tremor. By locating these cells relative to the anterior border of the somatosensory nucleus and the anterior commissure-posterior commissure line, it may be possible to select the optimal lesion site for the relief of parkinsonian tremor on a rational rather than an empirical basis.

An automated stereotactic machine has been interfaced to a surgical computer to complete a totally interactive surgical system capable of locating tumor volumes. Stepper motors, activated by the host computer, drive a three-dimensional slide to position the patient's head with respect to a fixed arc, locating the surgical target. Linear encoders on each axis create a closed-loop positioning system and a digital display for visual inspection of the slide's position. The 160-mm arc directs all instrumentation to its isocenter, regardless of the two angular settings, providing maximum freedom in selecting a safe trajectory to the target. Phantom test points compatible with computerized tomographic and magnetic resonance imaging were repeatedly scanned to determine the overall system accuracy, which approached 0.6 mm, depending on the spatial resolution of the image. This stereotactic device may be used to perform stereotactic laser craniotomies, biopsies, 192Ir implants for interstitial radiation, third ventriculostomies and functional procedures.

Twenty-five patients in a series of 51 undergoing partial or complete section of the corpus callosum for the treatment of intractable epilepsy experienced complex partial seizures among their seizure types preoperatively. Ten of these 25 patients have experienced no further complex partial seizures. Reduction in severity of seizures has been found in 11 of the 15 patients still experiencing this seizure type, and 3 have had greater than 80% frequency reduction. These findings are consistent with the electrophysiologic observations of Lieb on the relative unimportance of the hippocampal commissure in man and the behavioral observations of Quesney on unilateral versus bilateral temporal lobe seizure activity.

CT-guided stereotactic biopsy of lower brain stem lesions in 7 consecutive cases is discussed. A frontal transincisural approach was used. Five patients had astrocytomas histologically. The single patient who had undergone empirical radiation therapy prior to tissue diagnosis revealed only necrosis. One patient was found to have pathology suggestive of Leigh's disease. This patient was not radiated and is the first alive adult to have this diagnosis confirmed. Although controversy still exists in the management of brain stem lesions, we intend to demonstrate the value of tissue diagnosis in the management of such lesions.

The Pelorus stereotactic system, by its unique approach, alleviates the need for the traditional head frame and computer-generated coordinates which are common to most other systems. Despite its simplicity, it sacrifices nothing in terms of the range of problems for which it can be used to diagnose and treat. In fact, its unencumbered design may make it more appropriate for advanced procedures than conventional systems.

In 16 cases of stereotactic deep brain biopsy, a correlative study was made by computer tomography, positron emission tomography, and electrophysiological depth recording. This multimodal study is shown to be of great value in stereotactic biopsy of deep-seated cerebral lesions.