Unusual Clinical Manifestation Associated with Hypertrophic Olivary Degeneration

Abstract

Hypertrophic olivary degeneration (HOD) is a rare abnormality that is caused by a lesion in the Guillain-Mollaret triangle in the brainstem. 1,2 HOD usually occurs uni-and ipsilaterally to the lesion if the lesion is in the brainstem or contralaterally to the lesion if the lesion is in the cerebellum, as has been shown by MRI. The Guillain-Mollaret triangle is composed of the contralateral dentate nucleus, the ipsilateral red nucleus, and the ipsilateral inferior olivary nucleus (ION). The ION is a highly developed complex that is the main source of climbing fibers to the cerebellum. These fibers have powerful excitatory synapses on Purkinje cell dendrites. The inferior olive tends to possess a slow, rhythmic, spontaneous activity. HOD usually manifests itself with palatal myoclonus. 3,4 The causes of HOD include trauma, inflammation, tumor, degenerative disease, and surgical manipulation. We describe a 52-year-old woman who developed an unusual clinical presentation associated with HOD. Case ReportThe patient's history started 4 months before she was admitted to our hospital, when she complained of subjective balance disturbances. A neurological examination performed in another hospital had been considered normal. A brain MRI revealed cerebral (right parieto-occipital region and right and left temporal lobe at the subcortical level) and cerebellar (vermis, right cerebellar hemisphere, and the left cerebellar peduncle) metastases. MRI also showed a slightly increased T2 signal intensity in the right olivary nucleus. A total body CT detected lung cancer. She underwent resection of the cerebellar metastasis. After surgery, she presented gait ataxia and, approximately 20 days later, she progressively developed headache, dysarthria, an inability to walk as a result of ataxia, upper-limb plegia, and involuntary head movements. No palatal myoclonus was observed. A ventricular derivation was performed, though to no beneficial effect. Upon admission to our department (approximately 40 days after surgery), she was in a stuporous state with bilateral upper-limb plegia, as well as asynchronous involuntary head and jaw movements characterized by latero-lateral oscillations of the head and jaw (see Video 1). The right eye was directed toward the right, whereas the left eye was in the primary position. Gaze could be oriented toward the verbal stimulus. The patient did not have nystagmus. Pursuit movements could not be assessed. The involuntary movements persisted for most of the day, increasing in intensity after verbal and tactile stimulation, but disappeared during sleep. Although we did not perform electromyography, a video recording allowed us to estimate that the frequency of the latero-lateral oscillations was in the range of 2 to 3 Hz. EEG excluded epileptic abnormalities and documented regular physiological sleep features. Meningeal carcinomatosis and paraneoplastic syndrome were ruled out by the absence of neoplastic cells and cerebellar autoantibodies in the liquor. Brain MRI revealed increased T2 signal intensity in...