Pulsatile cerebral echo in diagnosis of brain death

Conclusive diagnosis of brain death can be made by the demonstration of prolonged cessation of cerebral blood flow. This report describes a simple method to determine the presence or absence of the blood flow in the brain by recording the pulsatile midline echo on one channel of the electroencephalogram (EEG) or on any four-channel monitoring system in the intensive care unit. A firm transducer holder has been developed to eliminate artifacts caused by transducer motion, The pulsations of the midline echo are assumed to be the result of displacement of the midline structures by the arterial injection of each cardiac systole. Thus, the absence of these midline pulsatile echoes correlates with the absence of cerebral blood flow and, if the absence persists over 30 minutes in the presence of normal blood pressure, then the result is brain death. Twenty-eight cases of clinical brain death with electrocerebral silence of EEG and 18 obtained patients with various types of cerebral pathology were examined by the echo-pulsation technique. Twenty-six of the 28 cases showed no pulsation of the midline echo. The validity of the technique was documented in four cases by four-vessel cerebral angiogram.

Histological reaction to various conductive and dielectric films chronically implanted in the subdural space

Thirty different test patches of various thin film materials were chronically implanted in the subdural space of cats to determine their suitability as components for proposed neuroprosthetic devices. In particular, materials employed by the microelectronics industry were screened, and reactions were found to be quite dependent on specific formulations or surface preparations of otherwise similar materials. A nonspecific but severe complication of pressure necrosis under thin films that spontaneously roll and curl in vivo was noted.

Simulated acute appendicitis secondary to ventriculoperitoneal shunt

A case of simulated acute appendicitis caused by a ventriculoperitoneal shunt is described. This case presented as a perplexing clinical problem. When the diagnosis was established by laparotomy, it was apparent that another complication should be added to the list of abdominal complications which occurred secondary to insertion of a ventriculoperitoneal shunt.

Simulated acute appendicitis secondary to ventriculoperitoneal shunt

A case of simulated acute appendicitis caused by a ventriculoperitoneal shunt is described. This case presented as a perplexing clinical problem. When the diagnosis was established by laparotomy, it was apparent that another complication should be added to the list of abdominal complications which occurred secondary to insertion of a ventriculoperitoneal shunt.

Electrical stimulation of the cerebral visual system in man

In patients undergoing thalamotomy for intractable pain, multi-contact platinum electrodes were stereotaxically implanted so that the striate cortex and geniculocalcarine tract could be stimulated to evaluate the feasibility of a visual prosthesis. The parameters of stimulation were 50–300 Hz, 0.1–1 msec pulse duration and 0.1–5 mA/phase. Phosphenes were evoked in 7 out of the 17 cases studied. The projection in space of the phosphene depended upon the site of stimulation. The configuration, color and brightness of the phosphene varied from a simple white or colored light to occasionally a multicolored complex pattern. Some phosphenes appeared to blink or flutter, some were stable in position, others appeared to move away radially from the fixation point. Histological studies on 6 of the brains suggested that the phosphenes were more often evoked from the striate cortex than from the geniculocalcarine fibers.

Thalamotomy for alleviation of intractable pain

17 patients had thalamotomies for alleviation of pain due to malignancy since January, 1970. In 12 of them, thalamic electrodes were implanted through occipital burr holes for subsequent radiofrequency thalamotomies. In 4 cases, the lesions were made by the bifrontal approach and 1 case was approached from the left occipital and right frontal. In 13 cases, the thalamic lesions were made in the vicinity of pulvinar, ventrocaudalis, parvocellularis, centromedianum and/or the adjacent structures. The size of histologically verified lesions in 7 specimens was 3 × 4 × 47 mm maximum and 4 × 3 × 4 mm minimum. Three of the 17 cases required no analgesics between thalamotomy and death or at least 6 months. In these cases, thalamic lesions were made in the vicinity of the posterior medial portion of thalamic nuclei and in one case the lesion was extended to the anterior thalamic radiation. In 7 cases requiring nonnarcotic analgesics, the lesions were located in the vicinity of the posterior median portion of thalamic nuclei, involving pulvinar, ventrocaudalis posterior, centromedian, internal medullary lamina or medial mass of thalamus. The remaining 8 thalamotomies in 7 patients required narcotics. In 4 of them, the lesions were made outside the posterior medial portion of thalamic nuclei. Histological confirmation is available in 6 cases.

Carotid-cavernous fistula: a controlled embolus technique for occlusion of fistula with preservation of carotid blood flow. Technical note

✓ A case is described in which a carotid-cavernous fistula was eliminated successfully with preservation of the carotid circulation by a small ball-shaped muscle embolus introduced via an arteriotomy in the cervical carotid. The intent is to lodge the embolus in the fistula without occluding the carotid siphon. A long thread is attached to the embolus to permit its withdrawal if its position in the siphon proves unsatisfactory. Neither the intracranial nor cervical carotid artery is ligated.