Cerebellar infarction: vertigo with ipsilateral cerebellar signs
A cerebellar infarction (a stroke in the cerebellum, which coordinates movement) may cause sudden, unrelenting vertigo, a spinning sensation, with cerebellar signs on the same side as the damage.
Remember
Sudden, unrelenting vertigo in a person with stroke risk factors, plus cerebellar signs on the same side as the damage, points to a cerebellar stroke rather than a peripheral cause (a disorder of the inner ear or its nerve).
Mnemonic
DANISH
- D dysdiadochokinesia
- A ataxia
- N nystagmus
- I intention tremor
- S slurred speech
- H hypotonia
Run through the six letters as a checklist of the main cerebellar signs when examining someone with sudden vertigo.
Think of a cerebellar infarction when a patient with risk factors for a stroke presents with sudden onset, unrelenting vertigo that is not affected by head position. Few other conditions cause vertigo that is truly unrelenting and sudden, and a good history is the key to telling a cerebellar infarction from other causes of vertigo such as Meniere disease (an inner ear disorder with attacks of vertigo, hearing loss and tinnitus, or ringing in the ears) and acute labyrinthitis (inflammation of the inner ear). Dizziness, headache, nausea and vomiting can be signs of cerebellar infarction, but with no other signs they are not enough to arouse suspicion.
The six main cerebellar signs together spell DANISH. Dysdiadochokinesia is the inability to perform rapid alternating movements, such as quickly turning one hand over and back on the other. Ataxia is poor balance and coordination, often with a wide-based gait (walking with the feet far apart to stay steady). Nystagmus is a rhythmic, repetitive, involuntary movement of the eyes. An intention tremor is a tremor that is absent at rest and appears only when the person tries to perform a task, becoming larger as the finger nears its target on finger-nose testing. Slurred speech and hypotonia (reduced muscle tone) are also cerebellar signs.
Cerebellar signs appear on the same side as the damage, which is called ipsilateral, because of a double crossing. Output from the cerebellum crosses the midline on its way to the cortex on the opposite side, and the corticospinal tract (the motor pathway from the cortex to the limbs) then crosses back again. The two crossings cancel out, so each side of the cerebellum ends up influencing movement on its own side of the body.
Key facts
- Vertigo that raises suspicion
- Sudden onset, unrelenting, position independent vertigo in a patient with risk factors for a stroke should be considered for a stroke.
- Which side
- Cerebellar signs appear on the same side (ipsilateral) as the cerebellar damage.
- Intention tremor
- It is absent at rest, worse as the limb approaches a target, and tested by finger-nose.
- Peripheral clues
- Hearing loss, tinnitus, ear pain or brief position-triggered vertigo point towards a peripheral cause rather than the cerebellum.
- Double crossing
- Cerebellar output crosses to the opposite cortex and the corticospinal tract crosses back, so the effects cancel out.
Exam traps
- Spastic weakness with increased tone and brisk reflexes is the picture of an upper motor neurone lesion (damage to the motor pathways running from the cortex to the spinal cord), not a cerebellar sign, because cerebellar disease typically reduces muscle tone (hypotonia) and causes incoordination.
- A resting tremor that improves with voluntary movement does not point to the cerebellum, because a cerebellar tremor is an intention tremor, which is absent at rest and worsens as the limb nears a target.
- Brief vertigo triggered by head movement, such as turning over in bed, is typical of benign paroxysmal positional vertigo, a peripheral cause lasting seconds to minutes, and it points away from a cerebellar infarction, which may cause continuous vertigo that is not affected by head position.
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