Hypertrophic olivary degeneration: A clinico-radiologic study

Abstract

Introduction The frequency and causes of hypertrophic olivary degeneration (HOD) are unknown. We compared the clinical and radiological characteristics of unilateral HOD and bilateral HOD. Methods We performed a search of a radiologic report database for patients who were radiologically diagnosed as having HOD. This database includes the patients examined at the Mayo Clinic in Florida and Arizona. We used the search terms “hypertrophic olivary degeneration,” “HOD,” and “olivary” in the reports recorded from 1995 to 2015. Pertinent medical records and magnetic resonance imaging (MRI) scans of the brain for those with HOD were reviewed retrospectively. Results We identified 142 MRI studies on 95 cases who had radiologically proven HOD, 39 cases had unilateral HOD and 56 with bilateral HOD. In symptomatic cases, the most common symptom was ataxia. Palatal tremor was observed in almost half of all HOD cases. While cerebrovascular diseases were the most frequent etiology in both types of HOD (n=24, 62% in unilateral; n=17, 30% in bilateral), more than half of bilateral HOD cases had an unknown etiology (52%, n=29), whereas only 13% (n=5) of the unilateral cases had an unknown etiology (χ2 test, P<0.001). The lesions of unilateral HOD had a tendency to improve radiologically over time, whereas those associated with bilateral HOD were likely to worsen (χ2 test, P<0.05). Conclusions Our study showed that bilateral HOD is more common than unilateral HOD. Half of bilateral HOD cases had no obvious cause and some worsened over time. This may implicate a possible primary neurodegenerative process.

Idiopathic bilateral hypertrophic olivary degeneration

“…Hypertrophic olivary degeneration is mostly bilateral, and half of bilateral cases may be implicated to primary neurodegenerative process 2. Our patient’s MRI revealed no abnormality involving the Guillain and Mollaret triangle.…”

The dentato–rubro–olivary pathway revisited: New MR imaging observations regarding hypertrophic olivary degeneration

“…HOD often remains asymptomatic and palatal tremor was seen in 39% of bilateral cases and in only 23% of the unilateral cases (Konno et al, 2016). HOD often remains asymptomatic and palatal tremor was seen in 39% of bilateral cases and in only 23% of the unilateral cases (Konno et al, 2016).…”

“…However, the relationship between palatal myoclonus and HOD remains controversial. HOD often remains asymptomatic and palatal tremor was seen in 39% of bilateral cases and in only 23% of the unilateral cases (Konno et al, 2016). It has been suggested that dysfunction of the ION rather than the hypertrophy is the cause of palatal tremor (Nishie et al, 2002).…”

Palatal Tremor with Progressive Ataxia Secondary to A Dural Arteriovenous Fistula

“…This analysis suggests a secondary degenerative process that may have been caused by venous hypertension and subsequent vasogenic edema as initial injury within the dentato‐rubro‐olivary pathway, formerly referred to as the Guillain–Mollaret triangle . Lesions involving this pathway, but sparing the olives, are known to cause denervation and degeneration of the ION and manifest as a tremor of branchial‐derived muscles . The underlying hypertrophic olivary degeneration (HOD) develops the most several weeks or months after denervation, which correlates with the delayed onset of the symptoms .…”

“…1 Lesions involving this pathway, but sparing the olives, are known to cause denervation and degeneration of the ION and manifest as a tremor of branchial-derived muscles. [2][3][4] The underlying hypertrophic olivary degeneration (HOD) develops the most several weeks or months after denervation, which correlates with the delayed onset of the symptoms. 2,4 Moreover, contralateral atrophy of the cerebellar cortex and dentate nucleus may occur in association with HOD.…”