Lesion of dentatothalamic pathways in severe post-traumatic tremor

Area of Science:

• Neuroscience
• Neurology
• Radiology

Background:

• Kinetic tremor is often associated with cerebellar outflow lesions, but direct neuropathological and neuroradiological evidence is limited.
• Post-traumatic tremor, particularly kinetic tremor, following severe head injury requires further investigation into its underlying pathoanatomy.

Purpose of the Study:

• To investigate evidence of dentatothalamic pathway lesions in patients experiencing severe kinetic post-traumatic tremor using magnetic resonance imaging (MRI).
• To correlate specific lesion locations within the dentatothalamic pathways with tremor characteristics and severity.

Main Methods:

• Nineteen patients with severe kinetic post-traumatic tremor underwent multiplanar MRI scans using high-field (2.0 T) and intermediate-field strength systems.
• A standardized MRI protocol included a heavily T2-weighted spin-echo sequence to detect hemosiderin deposits indicative of post-traumatic lesions.
• Lesions were classified based on their distribution within the dentatothalamic pathways (ipsilateral/contralateral, pre/post-decussational).

Main Results:

• Lesions within the dentatothalamic pathways were identified in 22 instances across the 19 patients.
• The majority of lesions involved the ipsilateral pre-decussational dentatothalamic pathway (56%), followed by the contralateral post-decussational course (28%).
• A correlation was observed between specific lesion types and tremor presentation, including parkinsonian-like rest tremor linked to contralateral substantia nigra lesions.

Conclusions:

• The study provides strong neuroradiological evidence implicating dentatothalamic pathway lesions in the pathogenesis of severe kinetic post-traumatic tremor.
• Findings support the hypothesis linking cerebellar outflow dysfunction to kinetic tremor and suggest distinct pathoanatomical sites for different tremor types, including 'midbrain' tremor.