Midbrain tremor and hypertrophic olivary degeneration after pontine hemorrhage

Abstract

A severe rest tremor arose in a patient's right arm 9 months after a pontine tegmental hemorrhage. Magnetic resonance studies at 4 and 10 months showed residual hemosiderin in the pons and increasing hypertrophic olivary degeneration (HOD) affecting primarily the left olive. The tremor was refractory to pharmacotherapy (clonazepam, propranolol, and levodopa), but was reduced after implantation of a thalamic stimulator device. Although pontine hemorrhage is among several common causes of HOD, it has not previously been appreciated as a cause of midbrain ("rubral") tremor. A disynaptic dentatorubroolivary tract associated with tremor and monosynaptic dentatoolivary tract associated with HOD may both be components of the rubroolivocerebellorubral loop implicated in midbrain tremor. Their proximity makes the combination of tremor and HOD after pontine tegmental damage plausible and even likely.

Holmes tremor in association with bilateral hypertrophic olivary degeneration and palatal tremor: chronological considerations. Case report

“…The peculiar mixture of rest, postural and kinetic tremor follows logically from this combination of pathology. Although attention has focused on the dentatorubral and dentatothalamic tract that forms the ascending limb of the dentate projection, components of the descending limb have also been implicated 6 . In particular, clinical evidence of a role for the rubroolivary tract is supported by experimental evidence of a rubroolivocerebellorubral loop 6 .…”

“…The neuronal hypertrophy begins at 3 weeks, neuronal and glial hypertrophy peak at 8-9 months, pseudohypertrophy (neuronal dissolution and gemistocytic astrocytes) occurs thereafter, gradually leading to olivary atrophic degeneration 13,14 . MRI permits antemortem visualization of HOD, which appears as a characteristic signal-enhancing lesion in proton-density and T2-weighted images 6,8,15 . Although virtually all patients who develop palatal myoclonus after a brain insult will have HOD, not all patients with HOD develop palatal myoclonus 6 .…”

“…MRI permits antemortem visualization of HOD, which appears as a characteristic signal-enhancing lesion in proton-density and T2-weighted images 6,8,15 . Although virtually all patients who develop palatal myoclonus after a brain insult will have HOD, not all patients with HOD develop palatal myoclonus 6 .…”

“…The anatomy of this tremor is complex and incompletely understood, but there has been broad agreement that the tremor follows interruption of the dentate projections pathways, particularly in the region of the superior cerebellar peduncle and red nucleus 6 . Symptomatic palatal tremor, also known as symptomatic palatal myoclonus, is a clinically, pathologically, and anatomically well defined movement disorder characterized as a stereotypic 1-3 Hz palatal contractions that commonly appears after a disruption of the so-called Guillain-Mollaret triangle (the dentatoolivary tract) [7][8][9] .…”

Deep brain stimulation of the nucleus ventralis intermedius for Holmes (rubral) tremor and associated dystonia caused by upper brainstem lesions

“…In selected cases DBS and thermocoagulation may offer an alternative therapeutic strategy. 1,8,15,16,21,23,27 Kim, et al, 15 reported on a 26-year-old man in whom unilateral Vim thalamotomy almost completely abolished Holmes tremor that had been caused by a midbrain tumor. Two additional case reports of patients with a midbrain cavernous angioma 16,23 document good to excellent clinical improvements in Holmes tremor following thalamic Vim stimulation.…”