Tsutomu Nakaoka

Oculomotor Nerve Anastomosis

We report a patient who underwent anastomosis of the left oculomotor nerve, which had been inadvertently and bluntly severed during the resection of a left parasellar chromophobe pituitary adenoma. Neural regeneration was confirmed by the reappearance of voluntary adduction of the eyeball, clinical signs of aberrant regeneration, and the appearance of an action potential on electromyography of the levator palpebrae superioris muscle 1 year after end-to-end anastomosis of the nerve.

Experimental Tremor Produced by Ventromedial Tegmental Lesion in Monkeys

Destruction of the ventromedial tegmentum (VMT) of the midbrain in the monkey has been known to produce tremor similar to that seen in Parkinsons disease. A neuroanatomical study by a silver impregnation method was conducted on 5 monkeys, demonstrating the characteristic flexed posture with hypokinesia of the contralateral upper limb (reliable premonitory sign of tremor) following destruction of VMT with a histologically proven lesion site. The results are summarized as follows: (1) the tractus nigrostriatus, (2) tractus tegmentalis centralis, (3) ascending fiber bundles going to the thalamus (particularly VL.X and VPLo) and (4) descending fibers leading to the bilateral substantia nigra constitute the bulk, if not all, of those neural tracts which pass through the VMT. This, along with the proven existence of fibers projecting to the thalamic nuclei, is thought to account for the rhythmic burst discharges recorded from the VL or Vim nucleus in the monkey and in Parkinsons disease patients. The present experimental study also seems to provide an additional anatomical basis for the concept that the tractus tectonigralis is involved in the mechanism of development of kinésie paradoxale.