Biomedical subjects
Publications and source records attributed to J Berkefeld.
Six cases with arteriovenous malformations (AVM) and intracerebral hematomas causing coma and tentorial herniation are presented. All patients were operated on acutely: The hematoma and malformation were removed. All patients survived. The acute operation on AVM with hematomas even in comatose patients with tentorial herniation is useful and possibly contributes to reduction of the total mortality.
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The organization and coordination of cutaneo-muscular reflexes of human finger and arm muscles to electrical stimulation of the digital nerves were investigated in 14 healthy volunteers. Thumb and finger muscles, although antagonists, showed homonymous reflex effects whereas the wrist and elbow muscles exhibited an reciprocally alternating reflex pattern in pairs of antagonists (Fig. 1). The mechanographical correlate of the homonymous reflex activity in distal muscles was a short release (Fig. 6). The receptive field for evoking such reflex effects covered both the palmar and dorsal surfaces of the fingers (Fig. 2). However, with stimulation of the thumb, the muscles of the fingers and of the wrist showed reflex reversal (Figs 3, 5). If the stimulus was moved from the second to the fifth fingers, a successive attenuation of the transcortical reflex component was seen (Fig. 4). It is concluded that the reflexes investigated are complex flexor reflexes comprising both a distal release and a proximal flexion synergy. According to opposition of the thumb in grasping, the receptive field terminates between thumb and index finger. These reflexes are supposed to have no assisting function during corticalized manipulatory movements--in contrast to the long-loop reflexes evoked by epicritic sensibility. The transcortical servo is blocked if the eliciting stimulus is contaminated by nociceptive signals; its receptive field is confined to those fingers used in the precision grip.
Cutaneo-muscular reflexes of the human hand were investigated with special regard to methodological characteristics. The reflexes were elicited by electrical stimulation of either the volar side of the index finger or the median nerve at the wrist, they were in both cases recorded from the abductor pollicis brevis muscle. Independent from the stimulus site, the reflex pattern consisted of four inhibitory and excitatory components (I1-E1-I2-E2): an H reflex was recorded from exclusively with median nerve stimulation. With increasing stimulus efficiency (stimulus strength or duration), the components I1, I2, and E2 were enhanced whereas the presumably transcortically mediated E1 component was successively attenuated. Systematic variation of the stimulus interval, in contrast, induced attenuation of I2 and slight enhancement of I1 only at short intervals (750 ms). Comparison of the reflex responses on both sides revealed a distinct asymmetry particularly of the amplitudes and--less distinct--of the latencies. Asymmetries of the E1 component should therefore be interpreted as pathologic only cautiously.
BACKGROUND AND PURPOSE: The clinical efficacy of filter devices in internal carotid artery (ICA) stent placement has been a matter of controversy. The aim of this retrospective study was to assess the number and extent of cerebral emboli, as represented by new lesions on diffusion-weighted MR imaging (DWI), in patients treated with filter-protected carotid stent placement. METHODS: Standard DWI (B0 = 1000) was performed within 48 hours before and 48 hours after filter-protected carotid stent placement in 50 patients with symptomatic, high grade (>70%), atherosclerotic ICA stenosis. Number, extent, and vascular territory of new DWI lesions after stent placement were assessed by consensus of 2 experienced neuroradiologists. Multifactorial statistical analysis was performed to determine risk factors associated with DWI lesions. RESULTS: New punctate DWI lesions with a median diameter of 2 mm were detected in 14 of 50 cases in the territory of the stented ICA and in 7 of 50 cases in other vascular territories. Median lesion load was 1 lesion (range, 1-15) per positive case in the stented ICA and 1 lesion (range, 1-7) in other vascular territories. All DWI lesions were clinically asymptomatic. Because of 1 hyperperfusion syndrome with temporary brain swelling, the 30-day stroke and death rate was 2%. Age >or =70 years was the only significant predictor for new DWI lesions, whereas sex, degree and site of stenosis, vascular risk factors, and stent and filter type showed no significant correlation. CONCLUSIONS: New DWI lesions after filter-protected carotid stent placement are substantially more frequent in the ipsilateral ICA territory compared with other vascular territories. Therefore, intraluminal filters cannot completely protect the brain from procedure-related embolization. However, individual lesion load and the risk of clinically relevant ischemia is low.