Introduction
Cerebellar examination is a core component of every neurological OSCE station. The cerebellum coordinates smooth, precise voluntary movement, balance, and fine motor control. Lesions produce a characteristic constellation of signs that are both clinically important and reliably tested in UK medical school examinations. A systematic approach using the DANISH mnemonic ensures no sign is missed.
Anatomy Recap
| Lesion Site | Predominant Features |
|---|---|
| Unilateral hemisphere | Ipsilateral limb ataxia, intention tremor, dysdiadochokinesis |
| Vermis | Truncal ataxia, wide-based gait, titubation |
| Bilateral | Gait ataxia, nystagmus, dysarthria |
Cerebellar lesions produce ipsilateral signs — unlike cerebral hemisphere lesions which produce contralateral signs.
🧠 Mnemonic
DANISH — Cerebellar Signs
D — Dysdiadochokinesis (failure of rapid alternating movements)
A — Ataxia (gait and truncal: wide-based, staggering, veers to ipsilateral side)
N — Nystagmus (horizontal, fast phase towards the side of the lesion)
I — Intention tremor (tremor worsens on approaching a target; absent at rest)
S — Speech: dysarthria — scanning or staccato speech, slurred
H — Hypotonia and Heel-shin test incoordination
Causes of Cerebellar Disease
| Category | Causes |
|---|---|
| Vascular | Cerebellar stroke (posterior circulation — PICA, AICA, SCA), haemorrhage |
| Demyelinating | Multiple sclerosis |
| Toxic | Alcohol (chronic and acute), phenytoin, carbamazepine, lithium |
| Neoplastic | Primary cerebellar tumour (medulloblastoma in children), metastases, paraneoplastic |
| Infectious | Cerebellitis (post-viral — chickenpox, EBV), abscess |
| Degenerative | Friedreich's ataxia, spinocerebellar ataxia subtypes |
| Metabolic | Hypothyroidism, Wilson's disease, vitamin B1 deficiency (Wernicke's) |
💎 Clinical Pearl
In a young patient with progressive cerebellar ataxia, consider Friedreich's ataxia (autosomal recessive, associated with cardiomyopathy and diabetes) and multiple sclerosis. In an older patient, consider vascular cause, alcohol, paraneoplastic, or metastatic disease.
The Cerebellar Examination — Step by Step
1. Speech Assessment
Ask the patient to repeat: *"British Constitution"* or *"Baby hippopotamus"*. Listen for:
- Dysarthria: slurred, imprecise articulation
- Scanning speech: words separated by abnormal pauses
- Staccato speech: explosive quality, equal stress on all syllables
2. Eye Movements — Nystagmus
Ask the patient to follow your finger through the full range of eye movements. Hold still at the extremes of lateral gaze.
| Nystagmus Type | Direction | Associations |
|---|---|---|
| Horizontal (direction-changing) | Fast phase to lesion side | Cerebellar disease |
| Horizontal (unidirectional) | Fast phase away from lesion | Peripheral vestibular (labyrinthitis, BPPV) |
| Vertical (upbeat) | Upward | Brainstem lesion, Wernicke's |
| Vertical (downbeat) | Downward | Foramen magnum lesion, Arnold-Chiari |
3. Upper Limb Coordination
Finger-Nose Test
Ask the patient to touch the tip of their nose with their index finger, then touch your finger held at arm's length, alternating rapidly. Move your target finger between repetitions.
- Intention tremor: tremor increasing as the finger approaches the target — absent at rest
- Past-pointing (dysmetria): the patient overshoots or undershoots your finger
⚠️ Red Flag
Intention tremor is a key differentiator: cerebellar tremor is worst on approaching the target and absent at rest. This distinguishes it from essential tremor (worse with sustained posture) and resting tremor of Parkinson's disease (absent on movement). Failure to distinguish these is a common OSCE error.
Dysdiadochokinesis
Ask the patient to alternately pronate and supinate their forearm rapidly, or repeatedly tap the back of one hand with the palm then back of the other.
- Normal: smooth, rhythmic, rapid
- Dysdiadochokinesis: irregular, slow, poorly rhythmic — like a broken metronome
This is one of the most sensitive cerebellar signs and should be tested bilaterally.
Rebound Test
Ask the patient to hold their arm horizontal and resist as you push their arm down. Suddenly let go — a cerebellar patient will overshoot and flail upwards. Always protect the patient's face with your free hand.
4. Lower Limb Coordination
Heel-Shin Test
Ask the patient to lie supine. Place their right heel on their left knee and run it slowly down the shin to the ankle, then lift and repeat. Observe for the heel veering off the shin or jerky movement. Test both legs.
5. Gait and Romberg's Test
In cerebellar disease, gait is wide-based, staggering, and irregular. The patient veers towards the side of the lesion and is unable to tandem walk (heel-to-toe).
Romberg's test: cerebellar ataxia is typically Romberg negative — equally unsteady with eyes open or closed. A positive Romberg (markedly worse with eyes closed) suggests posterior column/sensory ataxia instead.
6. Tone and Reflexes
- Hypotonia: the cerebellar limb may feel floppy
- Pendular reflexes: the leg swings several times after knee jerk rather than returning promptly
7. Completing the Examination
State: *"To complete my examination, I would assess blood pressure for postural hypotension, review medications and alcohol history, assess for signs of systemic disease (thyroid, hepatic), and arrange an MRI brain."*
Investigations in Cerebellar Disease
| Investigation | Rationale |
|---|---|
| MRI brain (with posterior fossa views) | Gold standard for structural, vascular, and demyelinating causes |
| TFTs | Hypothyroidism |
| LFTs, GGT, alcohol history | Alcohol-related cerebellar degeneration |
| Anti-Yo, anti-Hu antibodies | Paraneoplastic cerebellar degeneration |
| Vitamin B1 (thiamine) | Wernicke's encephalopathy |
FAQs
"Which side is the cerebellar lesion if a patient falls to the right?"
A patient with a right cerebellar hemisphere lesion will veer and fall to the right — cerebellar signs are ipsilateral to the lesion. The same lateralisation applies to nystagmus (fast phase towards the lesion side) and limb ataxia.
"How do I differentiate cerebellar from posterior column (sensory) ataxia in an OSCE?"
Perform Romberg's test. Cerebellar ataxia: Romberg negative (equally unsteady eyes open and closed). Sensory ataxia: Romberg positive (significantly worse with eyes closed). Check proprioception and vibration sense — lost in posterior column disease, intact in cerebellar disease.
"Is nystagmus always present in cerebellar disease?"
No. Nystagmus is more common with lesions affecting the vestibulocerebellum or its connections. Pure hemispheric lesions may have little or no nystagmus. Always test and document, but absence does not exclude cerebellar pathology.
"What is titubation and when should I think of it?"
Titubation is a tremor of the head or trunk, present at rest or with sustained posture, distinct from the limb intention tremor of cerebellar disease. It suggests vermis involvement and is classically associated with essential tremor and severe cerebellar degeneration.
"What is the commonest cause of acute cerebellar syndrome in a young adult?"
Acute cerebellar syndrome in a young adult should prompt consideration of multiple sclerosis (demyelinating plaque in the cerebellar peduncle), alcohol intoxication, drug toxicity (phenytoin, carbamazepine), or post-viral cerebellitis. MRI brain and CSF analysis are key investigations.
Related Posts
- Neurological Examination OSCE — full upper and lower limb neurological examination including tone, power, reflexes, and sensation
- Gait Assessment OSCE — cerebellar vs sensory ataxic gait and Romberg's test in detail
- Blood Results Interpretation OSCE — TFTs, LFTs, and metabolic causes of cerebellar disease