Dan Elmqvist

PRESSURE AND NERVE LESION IN THE CARPAL TUNNEL

In 16 patients, where the diagnosis carpal tunnel syndrome was electrophysiologically confirmed, the pressure between the median nerve and the carpal ligament was measured peroperatively. At rest the pressure was 18-64 mmHg, mean 31 mmHg. Passive volar and dorsal wrist flexion increased the pressure about three times. Isometric or isotonic maximal contractions of wrist and finger muscles, elicited by tetanic nerve stimulation increased the pressure to three to six times the resting value. These high pressures may be one of the causes of the nerve lesion in the carpal tunnel syndrome.

Pressures recorded in ulnar neuropathy

The pressure between the ulnar nerve and the arcade bridging the two heads of the flexor carpi ulnaris muscle was recorded peroperatively in ten patients with electrophysiologically confirmed ulnar neuropathy at the elbow. At rest, with the elbow extended, pressures ranged from 0 to 19 mm Hg but increased in flexion and during isometric contraction of the flexor carpi ulnaris muscle to maximal values above 200 mm Hg.

Daytime sleep tendency before and after discontinuation of antiepileptic drugs in preadolescent children with epilepsy

Summary: In 9 preadolescent children treated for epilepsy who had been free from seizures long enough for treatment to be discontinued, daytime vigilance was studied before and after discontinuation of antiepileptic drugs (AEDs). Comparisons were made with healthy controls. Multiple sleep latency test (MSLT), EEG, and a questionnaire were used. As part of the analysis of the MSLT, a new measure, the daily average sleep tendency (DAST), was constructed to overcome the problems with data censoring of the classic MSLT analysis. The patients had significantly (p < 0.001) higher daytime sleep tendency, even after drug discontinuation, than controls, a result that could neither be attributed to AED treatment nor to recent epileptic seizures or complicated epilepsy.

Nerve lesions after total hip replacement

In a prospective study 50 extremities in 46 patients with total hip replacement (THR) were examined clinically and with EMG preoperatively and 4 weeks postoperatively. Four patients with normal preoperative findings had electromyographical evidence of nerve lesions postoperatively and three of these had clinical symptoms; one patient had no clinical symptoms. Ten patients with normal pre- and postoperative findings were re-examined 1 year after the operation and still found to be normal. In 150 records of patients with THR reviewed retrospectively, only one doubtful case of nerve lesions was found.

CORRELATION BETWEEN SINGLE FIBRE EMG JITTER AND ENDPLATE POTENTIALS STUDIED IN MILD EXPERIMENTAL BOTULINUM POISONING

To study the correlation between single fibre EMG jitter and endplate potential amplitude we examined neuromuscular transmission in rats paralysed with botulinum toxin type A with single fibre EMG (SFEMG) in vivo and with intracellular microelectrode techniques in vitro. In muscles that were not completely paralysed SFEMG showed an increased neuromuscular jitter on nerve stimulation and in these muscles endplate potentials were of reduced amplitude. When the nerve stimulation frequency increased the jitter decreased. Intravenous injection of drugs that increase the acetylcholine release and endplate potential amplitude markedly reduced the jitter and the frequency dependence disappeared.

Role of I-123-iomazenil SPECT imaging in drug resistant epilepsy with complex partial seizures.

Fifteen patients with therapy resistant partial complex seizures with no structural lesions were examined interictally with 123‐I‐IOMAZENIL SPECT for measurement of benzodiazepine receptor distribution and with 99m‐Tc‐HMPAO SPECT for measurement of cerebral blood flow distribution. Regional abnormalities were correlated with the seizure onset patterns in EEG later recorded with implanted subdural strips. SPECT scans were made immediately after and at 1 and 2 h after intravenous injection of 123‐I‐Iomazenil. During that time there was a continuous change from an immediate flow‐related distribution toward a more specific receptor distribution. The decay of radioactivity of I‐123 in the brain was linear over time. Two patients on benzodiazepine treatment showed much faster elimination and showed no focal abnormalities. Eight patients with clear‐cut unifocal seizure onset showed concordant focal benzodiazepine defects. These patients showed a progressive focus/homotopic non‐focus enhancement over time much larger than the HMPAO scans in the same patients. Also the estimated focal area of abnormality was more restricted in the Iomazenil scans than in HMPAO scans. Five patients had more complex seizure onset patterns. In these patients a mismatch between the locations of abnormalities in Iomazenil and HMPAO scans were often found but benzodiazepine receptor abnormalities were more circumscribed also in these patients. The results suggest that 123‐I‐Iomazenil SPECT is more useful than 99m‐Tc‐HMPAO SPECT when applied interictally in patients with partial complex epilepsy, since in addition to demonstrate the hemispheric laterality of the epileptogenic zone, 123‐I‐Iomazenil appears to indicate its anatomical location with higher confidence, which could be of practical value for positioning of intracranial EEG electrodes.

SPECT imaging of gliomas with Thallium-201 and Technetium-99m-HMPAO

Sequential Thallium‐201 and Technetium‐99m‐HMPAO SPECT images were obtained from 7 patients with high‐grade gliomas and 5 patients with low‐grade gliomas. The histo‐pathological tumor‐type was verified from either biopsy specimens or resected tissue from surgery. There was an intense uptake of Thallium‐201 in all high‐grade gliomas. Compared to the contralateral hemisphere the mean uptake was 4.6 times higher. Low‐grade gliomas showed only a marginally increased Thallium‐201 uptake (1.4 times). No overlap existed between the two groups. There was no correlation between Technetium‐99m‐HMPAO uptake and tumor type. Thallium‐201 appears to be a promising radiopharmaceutical for differentiating high‐ and low‐grade gliomas, whereas Technetium‐99m‐HMPAO is not.

Beta camera low activity tumor imaging

A new technique, the beta camera, to complement film autoradiography, with fast quantitative imaging of beta particle-emitting radionuclides has been developed. It consists of a thin plastic scintillator and a light-sensitive microchannel plate detector. The thin tissue sample is mounted on the scintillator. Our first system had a high background and a moderate spatial resolution of 900 microns. We now report an improved system with a photomultiplier tube mounted on the scintillator of the microchannel plate detector. Only events registered by both detectors are accepted. A fast coincidence unit processes the signals, and if a time overlap exists, an event is generated in the beta camera. In the coincidence mode, images with low activity distribution of 201Tl (count rate 1 s-1) in 50 microns-thick slices of a human glioma tumor could be recorded with a spatial resolution of 500 microns.

A useful device for single fibre EMG-jitter measurements, the “jitter-bug” ☆

Abstract An electronic device containing filters, window trigger and two sweep function generators is described. The device facilitates greatly the display and measurement of single fibre EMG jitter.