Pendular Nystagmus and Palatomyoclonus from Hypertrophic Olivary Degeneration

Abstract

images in clinical medicineT h e ne w e ngl a nd jou r na l o f m e dic i ne n engl j med 360;9 nejm.org february 26, 2009 e12 A 50-year-old woman with hypertension had an acute pontine hemorrhage, as seen on computed tomography (Panel A, arrow), which resulted in quadriplegia. Thirty months later, she reported having difficulty reading because of oscillopsia. The physical examination revealed pendular nystagmus (two cycles per second) with a predominantly vertical component and some horizontal and torsional eye movements (Video 1). She also had palatomyoclonus, seen as rhythmic, involuntary contractions of the soft palate and pharyngopalatine arch (one to two cycles per second) (Video 2). T 2 -weighted magnetic resonance imaging of the brain showed hyperintensity and enlargement of the inferior olivary nuclei, findings that were compatible with a diagnosis of hypertrophic olivary degeneration (Panel B, arrowheads). The condition, which may be caused by trauma, infection, demyelination, neoplasm, or vascular injury in the components of the dentatorubroolivary pathway, results in olivary hypertrophy rather than atrophy. Myoclonic contractions of the soft palate and nystagmus represent the effects of transsynaptic degeneration of the inferior olivary nuclei. After treatment with trihexyphenidyl, there was some improvement in the patient's visual symptoms.

Neurons of the inferior olive respond to broad classes of sensory input while subject to homeostatic control

“…The functional role of climbing fiber activity Clinical manifestations of inferior olivary dysfunction range from ataxia and tremor to autism spectrum disorders (Llinás et al, 1975;Samuel et al, 2004;Bauman and Kemper, 2005;Lim and Lim, 2009;De Gruijl et al, 2013). Climbing fiber-evoked complex spikes are also essential for the proper timing, size and direction of movements as well as for the encoding of expected and unexpected deviations from planned movements (Wang et al, 1987;Simpson et al, 1996;Kitazawa et al, 1998;Ito, 2013;Yang and Lisberger, 2014;Herzfeld et al, 2018).…”

Imaging Features of Hypertrophic Olivary Degeneration

“…The classical clinical presentation of HOD is palatal myoclonus, involuntary cyclical movements of the soft palate, which can present within 2 to 40 months after the initial insult [ 12 ]. Other clinical findings include dentato-rubral or Holmes’ tremor and ocular myoclonus [ 13 14 ]. The association of hypertrophic olivary degeneration with palatal myoclonus is presumed to be the result of connections between the central tegmental tract and the nucleus ambiguus [ 3 ].…”

Inferior Olive: All Ins and Outs

“…Other types of tremor have also been described in combination with IO pathology. Hypertrophic degeneration of an IO, typically following a stroke, can lead to contralateral palatomyoclonus, which is an involuntary tremor of the soft palate (Deuschl et al 1994;Lim and Lim 2009). Palatomyoclonus occurs relatively often, but not always, together with pendular nystagmus (Deuschl et al 1994;Liao et al 2008;Lim and Lim 2009).…”

“…Hypertrophic degeneration of an IO, typically following a stroke, can lead to contralateral palatomyoclonus, which is an involuntary tremor of the soft palate (Deuschl et al 1994;Lim and Lim 2009). Palatomyoclonus occurs relatively often, but not always, together with pendular nystagmus (Deuschl et al 1994;Liao et al 2008;Lim and Lim 2009). The IO is also implicated in the pathology of other movement disorders, like dystonia (Raike et al 2005) and several forms of spinocerebellar ataxia (SCA), including SCA6, SCA7, and SCA23 (Holmberg et al 1998;Verbeek 2009;Wang et al 2010a;Wang et al 2010b).…”