CEREBELLUM & GAIT

The cerebellum plays a crucial role in coordination of movement, maintenance of posture, muscle tone, and balance. Cerebellar lesions do not cause paralysis but lead to incoordination and imbalance.

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Functional Divisions of the Cerebellum

1. Vestibulocerebellum

   • Flocculonodular lobe

   • Maintains balance and eye movements

2. Spinocerebellum

   • Vermis and intermediate hemispheres

   • Controls axial and limb movements

3. Cerebrocerebellum

   • Lateral hemispheres

   • Plans and initiates movement

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Peduncles

• Superior – efferent

• Middle – afferent from pons

• Inferior – afferent from spinal cord and medulla

Cerebellar lesions produce a constellation of signs collectively known as cerebellar syndrome. 

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1. Ataxia

• Incoordination of voluntary movements

• May involve limbs, trunk, or gait

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2. Dysarthria

• Slurred, scanning speech

• Words spoken with irregular rhythm

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3. Nystagmus

• Horizontal or vertical

• Gaze-evoked

• Direction changes with gaze

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4. Hypotonia

• Reduced muscle tone

• Pendular reflexes

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5. Intention Tremor

• Tremor worsens on goal-directed movement

Finger–Nose Test

• Past pointing indicates ipsilateral cerebellar lesion

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Heel–Knee–Shin Test

• Irregular, jerky movements suggest cerebellar disease

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Rapid Alternating Movements

• Dysdiadochokinesia present in cerebellar lesions

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Rebound Phenomenon

• Inability to stop movement when resistance is suddenly released

Ataxia is broadly classified based on underlying pathology.

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Cerebellar Ataxia

• Wide-based gait

• Not improved by visual input

• Associated with nystagmus and dysarthria

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Sensory Ataxia

• Due to posterior column dysfunction

• Improves with vision

• Positive Romberg sign

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Vestibular Ataxia

• Associated with vertigo

• Nystagmus prominent

• Falls towards side of lesion

Vermis Lesions

• Truncal ataxia

• Gait instability

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Hemispheric Lesions

• Limb ataxia

• Ipsilateral involvement

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Flocculonodular Lobe Lesions

• Balance disturbance

• Eye movement abnormalities

Gait is the final common pathway of motor, sensory, cerebellar, and vestibular systems.

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Observation of gait should include:

• Posture

• Base width

• Arm swing

• Turning

• Initiation and termination

Hemiplegic Gait

• Circumduction of affected leg

• Seen in stroke

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Spastic Paraparetic Gait

• Scissoring

• Seen in spinal cord lesions

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Cerebellar Gait

• Broad-based

• Irregular steps

• Reeling

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Sensory Ataxic Gait

• High stepping

• Stamping

• Worsens in darkness

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Parkinsonian Gait

• Stooped posture

• Shuffling steps

• Reduced arm swing

• Festination and freezing

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High Stepping Gait

• Seen in foot drop

• Due to peroneal nerve palsy or neuropathy

Romberg test helps differentiate sensory from cerebellar ataxia.

• Positive Romberg → sensory ataxia

• Negative Romberg → cerebellar ataxia

1. Determine type of ataxia

2. Look for associated signs

3. Assess onset and progression

4. Correlate with imaging

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Common Causes of Cerebellar Ataxia

• Stroke

• Alcoholism

• Tumors

• Multiple sclerosis

• Degenerative disorders