[Crossed cerebellar diaschisis. Study of a patient by magnetic resonance imaging and positron emission tomography].

INTRODUCTION

Crossed cerebellar diaschisis is a functional deficit in an area that is remote from that of a supratentorial brain lesion, although the two are anatomically and functionally connected. Deactivation of the contralateral cerebellar hemisphere occurs and is believed to be caused by a transneuronal metabolic depression of the cortico-ponto-cerebellar pathway. A reduction in the blood flow in the brain takes place and this gives rise to a diminished oxygenation of the cerebellar hemisphere. This finding can be evaluated by different functional imaging methods.

CASE REPORT: A 32-year-old female, without any relevant events in her personal history, presented an extensive supra-tentorial ischaemic lesion on the right-hand side. An MR angiography scan was performed, in which the homolateral middle cerebral artery and internal carotid artery were not identified. With no specific causation and suspecting a probable case of vasculitis (two days after the first ischaemic episode, the patient suffered another one in the left-hand occipital area, although this time it was smaller and clinically asymptomatic), a positron emission tomography/computerised tomography (PET/CT) scan was performed. The results revealed hypoenhancement of the radiotracer in the contralateral cerebellar hemisphere, which was interpreted as hypometabolism.

CONCLUSIONS

Determined by a possible prognostic value in the presence of crossed cerebellar diaschisis in supratentorial vascular episodes, with respect to the final clinical outcome of the patients, it is interesting to take this possibility into account when evaluating patients with an acute cerebrovascular accident, either by means of PET/CT, MR imaging (perfusion) or CT (perfusion).