THERE EXIST only few and rather contradictory data regarding possible projections of the nonacoustic inner ear to subcortical areas cranial to the oculomotor nuclei. In dogs in whom one of us (E. A. S.) had produced circumscribed lesions of the vestibular nuclei, Whitaker and Alexander traced ascending Marchi degenerations in the medial longitudinal fasciculus (MLF) not only to the oculomotor nuclei but also to the nucleus of the posterior commissure and the nucleus interstitialis of Cajal, to the nucleus ruber and to nuclei of the medial thalamus (nucl. medialis C, nucl. proprius tractus Meynerti, nucl. filiformis and nucl. paraependymalis). These fibers seemed to originate in all parts of the vestibular nuclei ; the fibers from the nucl. triangularis and Bekhterev chiefly reached the homolateral red nucleus ; those from the nucleus Deiters and nucleus tractus spinalis vestibularis were chiefly connected with the contralateral red nucleus.Besides a conduction in the lateral part of the MLF, Hassler assumes a conduction out$side this bundle. He states that the fasciculus tegmenti dorsolateralis on the dorsolateral border of the pontine reticular formation re¬ ceives impulses from the vestibular nuclei (homolateral nucleus Deiters and Bekhterev, contralateral nucleus tractus spinalis vestibularis) and is continued in Forel's tegmental fasciculi. These fasciculi lie lateral to the MLF ; at the level of the superior colliculi they ascend at the border of the central gray matter as far as the level of the posterior commissure and are supposed to end in the so-called nucleus ventro-intermedius externus of the thalamus.Other authors, however, trace the origin of Forel's fasciculi into the principal trigeminal nucleus (Carpenter) or into cell groups of the reticular formation (Lewandowsky, Russell).

The marriage of computerized tomographic (CT) scanning and stereotactic surgery opens up new technical possibilities, as it becomes feasible to introduce a probe into any lesion which is identified on a CT scan. The various CT stereotactic techniques are reviewed, and generally involve four variations. The head holder of a standard stereotactic appartus can be adapted to the CT scanner to interdigitate the coordinates of both devices in a known relationship. Second, some types of CT scanners allow the visualization of the vertical coordinate. Third, a stereotactic microdrive can be incorporated into the scanner. Finally, a simple aiming device can be attached to the patient''s head and repeated scans taken as the probe is advanced to the target. Various authors have reported the use of techniques for biopsy, aspiration of cysts or hematomas, insertion of radioisotopes, or as an adjunct to open surgery.

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