Changes in the distribution of climbing fiber-Purkinje cell (CF-PC) synapses are broadly part of the neurodegenerative process in the essential tremor (ET) cerebellum, a recent study found. Researchers studied 2 CF-PC synaptic pathologies (CF synaptic density and percentage of CFs in the parallel fiber [PF] territory) in the cerebella of 60 ET cases with a range of clinical presentations and 30 age-matched controls. They found:

• Compared to controls, ET cases had lower CF synaptic density and a higher percentage of CFs in the PF territory.
• ET cases with tremor onset <50 years and tremor onset ≥50 years did not differ significantly with respect to CF synaptic density and percentage of CFs in the PF territory.
• Similar results were found when comparing familial vs sporadic ET cases, and ET cases with head tremor vs those without head tremor.
• Among all ET cases, lower CF synaptic density was associated with lower PC counts and higher torpedo counts.
• In addition, higher percentage of CFs in the PF territory was associated with lower PC counts and higher torpedo counts.