Fabrication and characterization of a high-resolution neural probe for stereoelectroencephalography and single neuron recording.

This paper reports on the design, fabrication, and characterization of neural probes for stereoelectroencephalography (SEEG). The probe specifically targets focal epilepsy as key application. However, probes of this type can also be used for the diagnosis and treatment of other neural dysfunctions such as Parkinson's disease or tremor, typically requiring deep brain probes. The probe fabrication, of which most processes are parallel batch processes, relies on a novel fabrication concept for rolling and gluing thin film polyimide sheets with integrated electrodes into permanent cylindrical shapes with diameters down to 800 µm. The SEEG probes, comprise several macro-electrodes designed to record local field potentials, and micro-electrodes positioned in-between, dedicated to monitoring single unit activity, with a total channel count of 32, despite the small diameter. While platinum micro-electrodes with a diameter of 35 µm have impedances of about 255 kΩ at 1 kHz, impedance values down to about 1.5 kΩ have been measured for the macro-electrodes. The devices have shown good compatibility with magnetic resonance imaging in a 9.4 T magnet, enabling the precise post-operative probe localization within the brain.

Sydenham's chorea.

OBJECTIVE: To study the clinical profile in patients with Sydenham's chorea. DESIGN: Prospective. SETTING: Medical college and hospital. SUBJECTS: Sixty cases with Sydenham's chorea, between 1988 and 1994, were studied. Of these 36 were girls; the mean age at presentation was 11.1 yr (range 7-16 yr). RESULTS: Female predominance was apparent only after 9 years of age. There was a high familial incidence for both chorea and rheumatic fever. Generalized chorea was seen in 40 and hemichorea in 20 patients. The chorea lasted from 5 to 40 days; 13 patients had recurrent episodes. Gait disturbances, dysarthria and weakness were common. Six patients had co-existing heart disease, 4 had arthritis and one had subcutaneous nodules. A raised ESR and positive ASO titer were seen in 37 and 20 patients respectively. CONCLUSIONS: There was an increased incidence of Sydenham's chorea after 9 years of age in girls possibly suggesting the influence of female sex hormones. A high incidence of neurologic manifestations were noted. Acute phase reactants were raised in almost half the patients. Sodium valproate, whenever used, was effective in controlling the chorea.

Snake venom poisoning: experience with 633 cases.

Snake venom poisoning is a common medical emergency and the epidemiological features vary from region to region. We conducted a prospective study to review the epidemiology, treatment and outcome of snake venom poisoning in central Karnataka. Six hundred and thirty three cases of snake bite, seen in a teaching hospital, upto the age of 18 years, over a period of 8 years from 1985 to 1992 constituted the material for the study. Detailed history with special reference to the type of snake, circumstances leading to the bite and clinical consequences were studied and final outcome was noted. Males (n = 433) were bitten more often than females (n = 200). Two hundred and fifty six (40.4%) cases were in the age range of 11-15 years. The cases were seen during two periods, i.e., Oct, Nov, Dec (n = 210) and Apr, May, June (n = 199). Most (n = 506) were encountered in the lower limbs. Viper was the most common poisonous snake. Five hundred and seventy (90%) cases were from rural area. Coagulation time was prolonged in 371 (58.6%) cases, hemorrhagic syndrome was noticed in 354 (55.9%) cases, neurological involvement in 79 (12.5%) cases. Polyvalent anti snake venom (ASV) was given to 479 cases. Hypersensitivity to ASV was noted in 8 cases. Blood transfusion was given to 33 cases for the management of excessive bleeding. The death rate among snake victims was 5.2% (33 cases). The morbidity and mortality can be reduced substantially by increasing and maintaining confidence in good medical care and providing health education.