Project description:Hypertrophic degeneration of the inferior olive is mainly observed in patients developing palatal tremor (PT) or oculopalatal tremor (OPT). This syndrome manifests as a synchronous tremor of the palate (PT) and/or eyes (OPT) that may also involve other muscles from the branchial arches. It is associated with hypertrophic inferior olivary degeneration that is characterized by enlarged and vacuolated neurons, increased number and size of astrocytes, severe fibrillary gliosis, and demyelination. It appears on MRI as an increased T2/FLAIR signal intensity and enlargement of the inferior olive. There are two main conditions in which hypertrophic degeneration of the inferior olive occurs. The most frequent, studied, and reported condition is the development of PT/OPT and hypertrophic degeneration of the inferior olive in the weeks or months following a structural brainstem or cerebellar lesion. This "symptomatic" condition requires a destructive lesion in the Guillain-Mollaret pathway, which spans from the contralateral dentate nucleus via the brachium conjunctivum and the ipsilateral central tegmental tract innervating the inferior olive. The most frequent etiologies of destructive lesion are stroke (hemorrhagic more often than ischemic), brain trauma, brainstem tumors, and surgical or gamma knife treatment of brainstem cavernoma. The most accepted explanation for this symptomatic PT/OPT is that denervated olivary neurons released from inhibitory inputs enlarge and develop sustained synchronized oscillations. The cerebellum then modulates/accentuates this signal resulting in abnormal motor output in the branchial arches. In a second condition, PT/OPT and progressive cerebellar ataxia occurs in patients without structural brainstem or cerebellar lesion, other than cerebellar atrophy. This syndrome of progressive ataxia and palatal tremor may be sporadic or familial. In the familial form, where hypertrophic degeneration of the inferior olive may not occur (or not reported), the main reported etiologies are Alexander disease, polymerase gamma mutation, and spinocerebellar ataxia type 20. Whether or not these are associated with specific degeneration of the dentato-olivary pathway remain to be determined. The most symptomatic consequence of OPT is eye oscillations. Therapeutic trials suggest gabapentin or memantine as valuable drugs to treat eye oscillations in OPT.
Project description:BackgroundHypertrophic olivary degeneration (HOD) is a rare condition caused by lesions within the dentato-rubro-olivary pathway, resulting in ocular nystagmus and palatal myoclonus (oculopalatal tremor) but not usually dystonia. Dystonia is an uncommon association, and we present the first reported association of hypertrophic olivary degeneration with bilateral vocal cord dystonia.Case presentationA 33 year old male presented initially with acute hydrocephalus on the background of previous ventriculoperitoneal (VP) shunting for previously treated medulloblastoma. After revision of the VP shunt, the patient developed progressive hiccups and stridor leading to respiratory failure requiring intubation. Ocular pendular nystagmus and palatal myoclonus at 3 Hz was observed. Flexible nasendoscopy (FNE) demonstrated bilateral tonic adduction of the vocal folds with 3 Hz coarse supraglottic, pharyngeal and palatal rhythmic myoclonus. MRI imaging demonstrated T2 hyperintensity within the bilateral inferior olivary nuclei consistent with stage 3 radiological HOD.ConclusionsDystonia is a rarely reported phenomenon in HOD but is not unexpected with the inferior olivary nucleus implicated in dystonic disorders. We report the association of HOD with bilateral vocal cord adductor dystonia, a potentially life threatening condition.
Project description:BackgroundHypertrophic olivary degeneration (HOD), a rare form of transsynaptic degeneration, is secondary to dentato-rubro-olivary pathway injuries in some cases. We describe a unique case of an HOD patient who presented with palatal myoclonus secondary to Wernekinck commissure syndrome caused by a rare bilateral "heart-shaped" infarct lesion in the midbrain.Case presentationA 49-year-old man presented with progressive gait instability in the past 7 months. The patient had a history of posterior circulation ischemic stroke presenting with diplopia, slurred speech, and difficulty in swallowing and walking 3 years prior to admission. The symptoms improved after treatment. The feeling of imbalance appeared and was aggravated gradually in the past 7 months. Neurological examination demonstrated dysarthria, horizontal nystagmus, bilateral cerebellar ataxia, and 2-3 Hz rhythmic contractions of the soft palate and upper larynx. Magnetic resonance imaging (MRI) of the brain performed 3 years prior to this admission showed an acute midline lesion in the midbrain exhibiting a remarkable "heart appearance" on diffusion weighted imaging. MRI after this admission revealed T2 and FLAIR hyperintensity with hypertrophy of the bilateral inferior olivary nucleus. We considered a diagnosis of HOD resulting from a midbrain heart-shaped infarction, which caused Wernekinck commissure syndrome 3 years prior to admission and later HOD. Adamantanamine and B vitamins were administered for neurotrophic treatment. Rehabilitation training was also performed. One year later, the symptoms of this patient were neither improved nor aggravated.ConclusionThis case report suggests that patients with a history of midbrain injury, especially Wernekinck commissure injury, should be alert to the possibility of delayed bilateral HOD when new symptoms occur or original symptoms are aggravated.
Project description:The frequency and causes of hypertrophic olivary degeneration (HOD) are unknown. We compared the clinical and radiological characteristics of unilateral HOD and bilateral HOD.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.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 (?(2) 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 (?(2) test, P < 0.05).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.