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Biomedical subjects

P Birk

Publications and source records attributed to P Birk.

11 recordsLinked to original sources
PubMed1989

Functional neuroanatomy of the target area for the treatment of pathological tremor: an electrophysiological approach.

Within the target area used for the stereotactic treatment of pathological tremor, recording of somatosensory evoked potentials and single units and also electrical stimulation were performed. The data were correlated with anatomical sites as demonstrated in the stereotactic atlas of Schaltenbrand and Wahren by using a computer system. The affected anatomical area was predominantly the prelemniscal radiation and adjacent thalamic nuclei. The recordings and stimulation effects indicate that a direct spinal input is involved in the control of muscle tone and manifestation of tremor.

Brain↗
PubMed1987

Transformation modes in computerized human thalamic brain mapping.

An exact transfer of data intraoperatively gathered in thalamic nuclei to an anatomical atlas requires an efficient mathematical transformation mode. Three different kinds of transformation modes were analyzed: First, the AC PC distance was used as a parameter to correlate data with the atlas coordinate system. Second, the influence of the patients 3rd ventricle widths on the transformation procedure. Third, a transformation mode was performed based on "noise"-data, registered when the electrode penetrated patient's thalamus. This method was also used to combine the atlas and CT images.

Brain Mapping↗
PubMed1987

Computer-assisted analysis of functional anatomy of human ventrolateral thalamus.

A three-dimensional map was created by a computer-assisted analysis of functional and somatotopic organization of the target area in the human ventrolateral thalamus. Stimulation in the target area mostly elicited increased tone in skeletal muscles, with a concomitant decrease or stop of tremor. Despite averaging of all responses, no clear somatotopic organization could be demonstrated for the tonifying stimulation effects. In addition, somatosensory-evoked potentials were recorded, indicating an afferent projection to the target area.

Brain Mapping↗
PubMed1986

Somatosensory evoked potentials in the ventrolateral thalamus.

Within the target area (VL) used for the stereotactic treatment of parkinsonian tremor and spasmodic torticollis, electrical stimulation as well as recording of somatosensory evoked potential (SEP) was performed. The effects of stimulation in the target area are facilitation of muscle tone showing some degree of somatotopic distribution. The recorded SEPs indicate a projection of an afferent system (probably of muscle afferents) to the target area. We assume that the target area is a relay station involved in the control of muscle tone. The interruption of muscle afferents in combination with the correct somatotopic localization of the lesion is important for the therapeutic efficacy in parkinsonian tremor and spasmodic torticollis.

Afferent Pathways↗
PubMed1985

Digital image processing to handle neuroanatomical information and neurophysiological data.

An application of computer graphics technology to functional stereotactic neurosurgery is presented. Neuroanatomical images derived from a stereotactic atlas and information retrieved from a neurophysiological data base are drawn on a graphic monitor. The pictures are oriented and scaled according to appropriate landmarks. The aim of this work is to add confidence in the surgeon's selection of the probe trajectory and to improve the knowledge of sensory and motor organization within the thalamus.

Brain↗
PubMed1985

Iatrogenic bronchopleural fistula caused by feeding tube insertion.

Nutritional supplements administered through flexible small caliber feeding tubes are an increasingly popular substitute for parenteral hyperalimentation. Small and large caliber nasogastric tubes can inadvertently pass into the tracheobronchial tree, even in the presence of an endotracheal tube with an inflated cuff. We report three patients who had small caliber feeding tubes passed through the tracheobronchial tree perforating into the pleural space. Potential complications include immediate or delayed pneumothorax, tension pneumothorax, hydropneumothorax, and empyema. Prompt post-insertion chest radiography is required to verify correct placement of small caliber feeding tubes.

Aged↗
PubMed1984

Synchronous discharges in pairs of steadily firing motor units tend to form clusters.

Discharges of several motor units (MU) were simultaneously recorded during slight isometric contractions of the first dorsal interosseus muscle using bipolar needle electrodes. Correlograms constructed by counting the relative discharge intervals (1-ms binwidth) between two MU frequently showed narrow central peaks reflecting the occurrence of more synchronies than expected by chance. Diagrams of the temporal distribution of these synchronies revealed that they tend to form clusters consisting of several subsequent events associated with an adjustment of the firing pattern of the two MU. The synchronization described here may be explained by similar mechanisms as the so-called 'short-term synchronization'.

Adult↗