Multiple‐Cell Spike Density and Neural Noise Level Analysis by Semimicroelectrode Recording for Identification of the Subthalamic Nucleus During Surgery for Parkinson's Disease

Objective. For targeting the subthalamic nucleus (STN), we attempted to quantify the changes in multiple cell activities by computing the neural noise level and multiple‐cell spike density (MSD). Methods. We analyzed the neural noise level and MSD by stepwise recording at every 0.25‐mm increment during the final tracking in 90 sides of 45 patients with Parkinson's disease. The MSD was analyzed with cut‐off levels ranging from 1.2‐ to 2.0‐fold the neural noise level in the internal capsule or zona incerta in each trajectory. Results. The dorsal boundary of the STN was identified from an increase in the neural noise ratio in all sides. The ventral boundary was identifiable, however, from a decrease in the neural noise ratio in only 70 sides (78%). In contrast, both the dorsal and ventral boundaries were clearly identified from an increase and a decrease in the MSD, respectively, in all of the 90 sides. Conclusion. MSD analysis by semimicroelectrode recording represents a useful, practical, and apparently reliable means for identifying the boundaries of the STN.     

Altered erythropoiesis and increased hemolysis in hemoglobin M Akita (M Hyde Park beta92 His replaced by Tyr) disease.

Hb M Akita disease is a cyanotic hemoglobinopathy found in Akita Prefecture, Japan. The abnormal hemoglobin was found to be the same as Hb M Hyde Park (beta92 His replaced by Tyr) by chemical analysis in 1967. In this disease signs of accelerated hemolysis (serum bilirubin, 2.4 mg/dl; splenomegaly, 2 finger breadths; Hb, 10.7 g/dl; reticulocyte index, 2.7) were noted, but the causes of its slight anemia were revealed to be fairly complex by ferrokinetic study, RBC life-span measurement, and 99mTc myeloscintigram. The anemia in this disease is caused not only by shortened erythrocyte survival (T 1/2 = 11.5 days by 51Cr-tagging method) and sequestration of red cells in the spleen (Spleen: liver ratio = 2.5 approximately 3.0 by 51Cr-surface counting), but also by slow supply of erythrocytes to the peripheral blood from the bone marrow, presumably, related to the existence of unstable Hb M Akita and its derivative (Hb Akita) in the erythroid cells. Both Carrell's isopropanol test and Heinz body formation test were positive. In spite of maximally increased total erythropoiesis (8 times as high as the normal level; M:E ratio = 0.22:1.0), supply of red cells from the bone marrow to the peripheral blood was significantly decreased. The distribution of hematopoietic sites throughout the body was reasonably uniform.