Topodiagnostic value of blink reflex R1 changes: A digital postprocessing MRI correlation study

The aim of the study was to investigate the relation of the blink reflex R1 arc to known anatomical brainstem structures. Acute vascular brainstem les ions as identified by magnetic resonance imaging (MRI) of patients with iso lated R1 pathology were superimposed into a stereotactic anatomical atlas u sing a new method of digital postprocessing. Isolated acute brainstem lesio ns were documented by diffusion-weighted MRI in 12 of 24 patients with unil ateral R1 pathology. The lesions were located in the ipsilateral mid- to lo wer pons. In three patients only, the lesion had partial contact with the p rincipal sensory nucleus of the trigeminal nerve (PSN) on at least one leve l. In two patients, the lesion involved the medial longitudinal fasciculus. Most lesions were located medially and ventrally to the PSN on transverse slices. Our results underline the high localizing value of changes in the R 1 component of the blink reflex in patients with ipsilateral pontine functi onal deficits. Although available physiological evidence suggests that the R1 component of the blink reflex traverses an oligosynaptic pathway, this M R1 study does not support the view that synaptic transmission in the PSN su bserves R1. The reflex arc probably descends more medially and ventrally on its course to the facial nucleus. (C) 2001 John Wiley & Sons, Inc.