Thalamic syndromes – clinical overview

The thalamus is a paired, deep-seated structure in the brain that acts as a major relay station for sensory information. It also participates in motor control, alertness, memory, attention and emotional behaviour.

A lesion in different parts of the thalamus can produce distinct neurological syndromes. The clinical presentation depends on the vascular territory and the nuclei involved.

Important thalamic syndromes

1. Dejerine–Roussy syndrome (Thalamic pain syndrome)

Usually follows a posterolateral thalamic infarction.

• Contralateral loss or impairment of sensation.
• Later development of severe burning pain.
• Hyperpathia and allodynia.
• Pain may be disproportionate to the stimulus.
• Often difficult to treat.

2. Thalamic sensory syndrome

• Contralateral hemisensory loss.
• Impaired proprioception and vibration.
• Impaired two-point discrimination.
• Sensory ataxia.
• Sometimes astereognosis.

3. Paramedian thalamic syndrome

Usually involves the paramedian thalamic nuclei.

• Altered consciousness or hypersomnolence.
• Memory impairment.
• Confusion.
• Vertical gaze palsy.
• Behavioural and cognitive changes.

Bilateral paramedian infarction can occur due to occlusion of the artery of Percheron.

4. Anterior thalamic syndrome

• Prominent memory impairment.
• Confabulation.
• Executive dysfunction.
• Apathy and behavioural changes.

5. Thalamic aphasia

Usually associated with dominant thalamic lesions.

• Word-finding difficulty.
• Reduced verbal fluency.
• Paraphasic errors.
• Impaired verbal comprehension in some cases.

6. Thalamic neglect syndrome

Usually associated with nondominant thalamic injury.

• Contralateral spatial neglect.
• Impaired attention.
• Reduced awareness of the affected side.

Vascular territories and clinical correlation

Arterial territory Predominant clinical features Tuberothalamic (polar) Memory and behavioural abnormalities Paramedian Altered consciousness, memory and vertical gaze abnormalities Inferolateral Contralateral sensory loss, pain, ataxia Posterior choroidal Visual, sensory and cognitive abnormalities

Regarding your Facebook link: I attempted to open the reel, but Facebook did not allow the video to load. If you upload the video or a few screenshots, I can explain the exact thalamic syndromes discussed in it, including their neuroanatomical localisation, clinical signs, MRI findings and differential diagnosis.

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