Objectives: To evaluate the sensitivity of diffusion weighted magnetic resonance imaging (MRI) for the diagnosis of clinically suspected reversible ischaemic deficits of the brainstem. Methods: A total of 158 consecutive patients presenting with acute signs of brainstem dysfunction were investigated using EPI diffusion weighted MRI within 24 hours of the onset of symptoms. High resolution T1 and T2 weighted imaging was performed as a follow up after a median of six days Results: Fourteen of the 158 patients had a complete clinical recovery within 24 hours (transitory ischaemic attack (TIA)), and 19 patients recovered in less than one week (prolonged reversible neurological deficit (RIND)). Diffusion weighted MRI showed acute ischaemic deficits in 39% of patients with transient neurological deficits. The detection rate seemed to be higher in patients with longer lasting symptoms, but the difference between patients with TIA (29%) and RIND (47%) was not significant. Conclusions: Diffusion weighted MRI is a sensitive indicator of acute ischaemic brainstem deficits even in patients with reversible neurological deficit. Early identification of patients with TIA and increased risk of stroke may influence acute management and improve patient outcome.

The aim of the study was to investigate the relation of the blink reflex R1 arc to known anatomical brainstem structures. Acute vascular brainstem lesions as identified by magnetic resonance imaging (MRI) of patients with isolated R1 pathology were superimposed into a stereotactic anatomical atlas using a new method of digital postprocessing. Isolated acute brainstem lesions were documented by diffusion-weighted MRI in 12 of 24 patients with unilateral R1 pathology. The lesions were located in the ipsilateral mid- to lower pons. In three patients only, the lesion had partial contact with the principal sensory nucleus of the trigeminal nerve (PSN) on at least one level. 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 R1 component of the blink reflex in patients with ipsilateral pontine functional deficits. Although available physiological evidence suggests that the R1 component of the blink reflex traverses an oligosynaptic pathway, this MRI study does not support the view that synaptic transmission in the PSN subserves R1. The reflex arc probably descends more medially and ventrally on its course to the facial nucleus.

We investigated the reliability of a new digital post-processing magnetic resonance imaging (MRI) technique in ischemic brain stem lesions to identify relations of the lesion to anatomical brain stem structures. The target was a medial longitudinal fasciculus (MLF) lesion, which was evident from ipsilateral internuclear ophthalmoplegia (INO). Sixteen patients with acute unilateral INO and an isolated acute brain stem lesion in T2- and EPI-diffusion weighted MRI within 2 days after the onset of symptoms were studied. The MRI slice direction was parallel and perpendicular to a slice selection of a stereotactic anatomical atlas. The individual slices were normalized and projected in the digitalized atlas. The eye movement disorder was monitored by electro-oculography. In all patients with clinical or subclinical electro-oculographically documented INO and MRI proven brain stem infarction the lesion covered or at least partially overlapped the ipsilateral MLF at one or more atlas levels. We conclude that digital post-processing MRI with normalizing and projecting brain stem lesions in an anatomical atlas is a reliable method to demonstrate the anatomical structures involved by the lesion. Combined with electrophysiological brain stem testing, this method may be a useful tool to identify incompletely understood pathways mediating brain stem reflexes or the generators of evoked potentials.

The aim of this study was to evaluate the applicability, sensitivity, and predictive power of diffusion-weighted MR imaging (DWI) in the diagnosis of vertebrobasilar infarction. From 1997 to 2002, we prospectively recruited 268 patients with acute signs and symptoms suspective of vertebrobasilar ischemia. The patients underwent biplanar EPI-T2 and EPI DWI within 24 h after onset of symptoms and high-resolution MRI as a control within 7 days. One hundred twenty-one patients had additional CT scanning. The DWI revealed acute vertebrobasilar infarction in 71.0%. The mean time exposure of DWI was 8 min and thus no more than that of CT imaging. It showed significantly more acute lesions than CT imaging (28.0%), but additional high-resolution MRI was not able to reveal more lesions than DWI alone. Even in 42 patients with reversible brainstem or cerebellar symptoms classified as TIA or PRIND, DWI demonstrated acute ischemia in 42.8%. Sixty-three patients with optimal final diagnosis of vertebrobasilar ischemia had normal DWI. One week after onset of symptoms, 88.9% of these patients had recovered completely or showed minimal symptoms. Therefore, DWI is a sensitive indicator of acute vertebrobasilar ischemia. It is no more time-consuming than CT imaging, and normal DWI is a predictor of good clinical outcome in patients with brainstem or cerebellar infarction.