Ultrasonographic Assessment of the Distance of Sciatic Nerve Bifurcation from the Popliteal Crease and its Depth from Skin in Volunteers.

Background Sciatic nerve block used for various surgeries below knee and for maintenance of analgesia demonstrates wide variability regarding its bifurcation into tibial and common peroneal nerves, frequently accounting for incomplete nerve blocks. Objective To determine the variation of sciatic nerve bifurcation among Nepalese volunteers. Method This cross sectional study was conducted in the Department of Anesthesiology of Kathmandu Medical College Teaching Hospital from March to May 2019, where 110 healthy volunteers underwent ultrasonography of sciatic nerve starting from popliteal fossa to its bifurcation. The distance between the bifurcation of sciatic nerve from popliteal crease and depth of the nerve at that point from the skin were measured. Result The mean distance at which sciatic nerve bifurcated from the popliteal crease was 5.42 ± 1.37 cm. Most commonly, the sciatic nerve bifurcated at a distance of 5-7 cm from the popliteal crease in 110 limbs (50.45%). However, in 80 limbs (36.69%), the bifurcation was found at less than 5 cm from the popliteal crease. The depth of the nerve from the skin at the point of bifurcation was 1.72 ± 0.54 cm, with results showing it was deeper in females compared to males (p value < 0.001). Conclusion This study showed that though the distance of sciatic nerve bifurcation from the popliteal crease in our study group was coherent with the published literature of 5-12 cm; many volunteers also had this bifurcation at distances less than 5 cm. Females showed nerves to be deeper at the point of bifurcation than males.

Role of S-100 Immunostain as An Auxiliary Diagnostic Aid in Leprosy.

INTRODUCTION: Histopathologic diagnosis of leprosy is difficult when Bacillary Index (BI) is zero and neural involvement are not easily identifiable on routine Hematoxylin and Eosin stain. This study was undertaken to study the role of S-100 immunostaining in demonstrating different patterns of nerve involvement in various types of leprosy. METHODS: Thirty one skin biopsies with clinico-histopathologic diagnoses of leprosy over a period of two years were included in the study. Ten cases of non-lepromatous granulomatous dermatoses (including eight cases of lupus vulgaris and two cases of erythema nodosum) were used as controls. Tissue sections from all cases and controls were stained with Hematoxylin and Eosin (H&E) stain, Fite stain and S-100 immunostain. The H&E stained slides were used to study the histopathological features, Fite stained slides for Bacillary Index and S-100 for nerve changes. RESULTS: Neural changes could be demonstrated in the entire spectrum of leprosy using S-100 immunostaining. The most common pattern of nerve destruction in the tuberculoid spectrum was fragmented and infiltrated whereas lepromatous spectrum showed mostly fragmented nerve twigs. Intact nerves were not detected in any of the leprosy cases. CONCLUSIONS: S-100 immunostain is a useful auxiliary aid to the routine H&E stain in the diagnosis of leprosy especially tuberculoid spectrum and intermediate leprosy.

Pharmacokinetic and pharmacodynamic interactions of mefloquine and quinine.

This study was carried out to investigate the pharmacokinetic and pharmacodynamic interactions between two antimalarial drugs, mefloquine and quinine. A randomized, comparative, three-way crossover study was performed in seven healthy male Thais after the administration of three drug regimens on three occasions i.e., a single oral dose of quinine sulfate (600 mg), mefloquine (750 mg) alone, or the combination of mefloquine (750 mg) and quinine (600 mg given 24 h after mefloquine). QTc interval was significantly prolonged in subjects following the combination regimen (at 2.5, 3, 4, 6, 8, 12, 18, 24 h after the quinine dose) but no abnormal clinical signs or symptoms were found. There were no significant changes in vital signs or routine laboratory values in any of the subjects. The pharmacokinetics of mefloquine and quinine were influenced by the presence of the other drug. Greater blood schizonticidal activities were collected from the sera of subjects on the combination regimen than from the sera of subjects the quinine or mefloquine regimens. The minimum inhibitory concentrations (MICs) of the equivalent concentrations (Eqs) of quinine or mefloquine, which completely inhibited the growth of the K1 strain of Plasmodium falciparum in vitro (MICs of quinine Eq and mefloquine Eq) were significantly lower in the sera of subjects on the combination regimens, than in the sera of subjects on mefloquine or quinine alone [MICs of quinine Eq: 41.2 (21.25-73.5) vs. 135 (118-150) ng/ml; MICs of mefloquine Eq: 18.2 (17-19.2) vs. 25.2 (24.4-26.8) ng/ml].