Imaging Features of Hypertrophic Olivary Degeneration.

Ruth Van Eetvelde,T Backaert,B Geerts,S Dekeyzer,D Hemelsoet,M Lemmerling,N Favoreel,C Sommeling

doi:10.5334/jbr-btr.1065

Abstract

Hypertrophic olivary degeneration (HOD) is a unique form of transneuronal degeneration caused by a disruption of the dentato-rubro-olivary pathway, also known as the triangle of Guillain-Mollaret. The triangle of Guillain-Mollaret is involved in fine voluntary motor control and consists of both the inferior olivary nucleus and the red nucleus on one side and the contralateral dentate nucleus. Clinically, patients classically present with symptomatic palatal myoclonus. Typical magnetic resonance imaging findings include T2-hyperintensity and enlargement of the inferior olivary nucleus evolving over time to atrophy with residual T2-hyperintensity. In this article, we provide a case-based illustration of the anatomy of the Guillain-Mollaret-triangle and the typical imaging findings of hypertrophic olivary degeneration.

Highlights

Hypertrophic olivary degeneration (HOD) is usually caused by a lesion along the dentate-rubro-olivary pathway, known as the anatomic triangle of Guillain-Mollaret
The aim of this article is to illustrate the anatomy of the dentate-rubro-olivary pathway on Magnetic resonance imaging (MRI), illustrate the typical imaging findings and causes of HOD, and discuss its radiological differential diagnosis
Anatomy of the Guillain-Mollaret Triangle Hypertrophic olivary degeneration (HOD) is a rare type of neuronal degeneration caused by damage to the dentato-rubro-olivary pathway or the triangle of GuillainMollaret (Figures 4 and 5) [1]

Summary

Introduction

Hypertrophic olivary degeneration (HOD) is usually caused by a lesion along the dentate-rubro-olivary pathway, known as the anatomic triangle of Guillain-Mollaret. The classical clinical presentation consists of palatal myoclonus. HOD can be an incidental imaging finding in asymptomatic patients. In slightly less than half of patients, no causative lesion along the denta-rubroolivary pathway can be detected. Awareness of the imaging characteristics of the entity is warranted to accurately differentiate it from primary lesions in the medulla oblongata. The aim of this article is to illustrate the anatomy of the dentate-rubro-olivary pathway on MRI, illustrate the typical imaging findings and causes of HOD, and discuss its radiological differential diagnosis

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Discussion

Conclusion