Presentation
Palatal tremor.
Patient Data
Atrophic change and prior bleeding are seen at the midbrain and thalamus on the left side with T2 hypointensity and T1 hyperintensity. Blooming artifact is seen in this area on susceptibility-weighted images (SWI).
Mild enlargement of the left side of the medulla with T2 hyperintensity is evident which is consistent with Hypertrophic Olivary Degeneration (HOD) following prior hemorrhage in the midbrain - a component of the Guillain-Mollaret triangle.
The note is made of slight bilateral SDH with left-side predominancy. Gliosis and malacia are evident at the tip of the left temporal lobe, parasagittal regions of frontal lobes, and body of corpus callosum compatible with post-traumatic injuries. There is a VP shunt at the ventricular system.
Superior Cerebellar Peduncle (SCP), Central Tegmental Tract (CTT), inferior Cerebellar Peduncle (ICP)
Case Discussion
Hypertrophic Olivary Degeneration (HOD) is a rare trans-synaptic neurodegenerative disorder caused by an injury within the Guillain-Mollaret Triangle (GMT) or Dento-Rubro-Olivary tract which is an anatomical-functional inhibitory loop 1. Damage to this pathway may cause oculopalatal myoclonus and upper limb tremors 2.
Familiarity with this entity is mandatory to avoid misinterpretation of the medullary lesion.
Case courtesy of Dr. Parisa Hajalioghli, Tabriz University of Medical Sciences, Iran.
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