Thalamic infarctions: differential effects on vestibular function in the roll plane (35 patients)

Area of Science:

• Neuroscience
• Ophthalmology
• Neurology

Background:

• Vestibular function is crucial for spatial orientation.
• Thalamic and mesodiencephalic lesions can affect vestibular pathways.
• The interstitial nucleus of Cajal (INC) plays a role in eye-head coordination.

Purpose of the Study:

• To investigate the tonic effects of acute thalamic infarctions and mesodiencephalic hemorrhages on vestibular function in the roll plane.
• To identify the specific brain structures responsible for ocular tilt reactions (OTR).

Main Methods:

• Assessed subjective visual vertical (SVV), ocular torsion (OT), skew deviation, and lateral head tilt in 35 patients with acute thalamic infarctions and 5 with mesodiencephalic hemorrhages.
• Categorized thalamic infarctions into paramedian, posterolateral, and anterior polar subtypes.

Main Results:

• Complete OTR (head tilt, skew deviation, OT, SVV tilt) occurred in 8/14 paramedian infarctions, linked to rostral midbrain tegmentum ischemia including the INC.
• Moderate SVV tilts (ipsiversive or contraversive) were observed in 11/17 posterolateral infarctions, associated with vestibular thalamic nuclei involvement.
• Anterior polar infarctions did not impact vestibular function in the roll plane.

Conclusions:

• The INC is the most rostral brainstem structure mediating eye-head coordination in roll.
• Thalamic lesions, particularly paramedian ones affecting the INC pathway, can cause significant vestibular dysfunction.
• Posterolateral thalamic infarctions involving vestibular nuclei can lead to moderate SVV deviations.