Neurology · MU Sofia

30. Syndromes of the internal capsule and the thalamus

Covers the internal capsule syndrome, starting with the anatomy of the capsule and its corticospinal, corticobulbar and thalamocortical fibres, then the capsular clinical picture of proportional hemiplegia, upper motor neuron signs, central facial palsy and dysarthria, and common causes. Moves on to the thalamic syndrome, including contralateral hemihypaesthesia and Dejerine-Roussy thalamic pain syndrome. A comparison table sets the two syndromes side by side.

Inside: 2 sections · 1 table · 16 flashcards · 1 min

Topic 30 of 88 in the MU Sofia syllabus for Neurology (Medicine, Year 4). The free AceMed note covers it in 2 sections, about 170 words (1 min of reading), with 16 flashcards.

In this note

  1. Syndromes of the internal capsule and the thalamus
  2. II.Thalamic Syndrome

Syndromes of the internal capsule and the thalamus

I.Internal Capsule Syndrome

Anatomy

The internal capsule is a compact bundle of ascending and descending fibers located between:

  • Caudate nucleus and thalamus (medially)
  • Lentiform nucleus (laterally)

It contains: Corticospinal fibers. Corticobulbar fibers. Thalamocortical sensory fibers

Because fibers are densely packed, even a small lesion can cause major deficits.

Clinical Features (Capsular Syndrome)

1.Pure Motor Hemiplegia/Hemiparesis

  • Contralateral: Face. Arm. Leg
  • Affected equally ("proportional hemiplegia").

2.UMN Signs: Hyperreflexia. Spasticity. Babinski sign.

3.Corticobulbar Involvement: Central facial palsy. Dysarthria

4.Sensory Disturbance: May occur if thalamocortical sensory fibers are involved.

Common Causes: Lacunar infarction. Hypertensive hemorrhage. Small vessel disease

II.Thalamic Syndrome

Anatomy

The thalamus is the major sensory relay station of the brain.

Functions: Sensory perception. Pain modulation. Motor integration. Consciousness and attention

Clinical Features :

1.Contralateral Hemihypesthesia

  • Loss or reduction of: Touch. Pain. Temperature. Proprioception

2.Thalamic Pain Syndrome (Dejerine-Roussy Syndrome): Develops weeks to months after a thalamic lesion.

  • Features: Severe spontaneous burning pain. Hyperalgesia. Allodynia. Pain disproportionate to stimuli
  • Other Findings: Sensory ataxia. Mild hemiparesis. Choreoathetosis (occasionally). Emotional disturbances
  • Causes: Thalamic infarction. Thalamic hemorrhage. Tumors

Comparison

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