Abstract TP163: Hypertrophic Olive Degeneration Causing Novel Neurological Symptoms After Stroke: A Case Series

Background: Ischemic and hemorrhagic strokes in the brainstem and cerebellum can affect the dentate-rubro-olivary -pathway. Lesions in this functional loop (called triangle of Guillain and Mollaret ) may result in hypertrophic olivary degeneration (HOD). Characteristic symptoms include rhythmic palatal tremor, primarily vertical pendular nystagmus, and Holmes-tremor of the upper limbs. This case series explores the course of the disease and its clinical presentation, in order to provide an improved understanding of HOD after stroke. Materials and methods: The neuro-radiological database of our university hospital was scanned for the term hypertrophic olivary degeneration and related keywords (in German) . Between 2010 and 2017, a total of 27 HOD cases were identified, of which 12 patients had suffered a stroke in their medical history. Results: Mean age of the 12 patients was 51.4 (+/-13.6) years. Eight patients had intracerebral hemorrhage, 3 ischemic stroke and one subarachnoid hemorrhage as causative event. Lesions were located pontine (n=7), cerebellar (n=4), and ponto-mesencephalic (n=1). Leading symptoms were palatal tremor (55%), Holmes tremor (18%), pendular nystagmus (18%), and dysarthria (73%). Based on clinical findings and brain imaging we designed a model allowing to predicting the side of HOD according to lesion location (Figure). By this we were able to identify and illustrate lesion sites able to induce bilateral HOD. Conclusions: Strategic lesions within the Guillain-Mollaret-Triangle in the posterior fossa may lead to unilateral or bilateral HOD. Even though the clinical syndrome of HOD is characteristic, diagnosis is often prolonged due to imprecise examination and misinterpretation of the findings. Future studies are desirable defining the incidence of HOD and evaluating therapeutic options.