- Clinical science
The cerebellum is the region of the brain responsible for controlling stance, gait, and balance, as well as the coordination of complex and goal-directed movements. The acute onset of cerebellar symptoms is considered a medical emergency and is usually due to stroke, hemorrhage, or cerebral edema. Chronic cerebellar syndromes are either acquired (e.g., alcoholism, tumors, paraneoplastic) or genetic. Cerebellar injury is characterized by impaired cerebellar function, resulting in ataxia, imbalance, uncoordinated movements (dysmetria), speech (dysarthria), and oculomotor disorders (nystagmus). Vertigo may also occur if the vestibulocerebellar system is affected. The diagnosis is based on the evaluation of these symptoms and is confirmed by detection of the underlying cause in imaging or laboratory or genetic tests. As treatment of these causes is often not possible, management is focused on supportive measures such as physiotherapy and psychological support groups.
- Infarction, TIA
- Head trauma, edema, hemorrhage
- Medication, toxins, and poisons: barbiturates, benzodiazepines, heavy metals, and chemotherapy (fluorouracil, cytarabine)
- Subacute and chronic
The clinical features vary depending on the underlying cause and severity of cerebellar injury. Symptoms manifest ipsilaterally to the lesion site.
- Cerebellar ataxia
and (postural, action, intention tremor)
- Finger-to-nose test: patients with dysmetria are unable to touch the tip of their nose with their index finger ; patients with tremor perform the test with shaking fingers
- Heel-knee-shin test: inability to slide the heel of one foot down the shin of the opposite leg; the heel will deviate to alternate sides
- Inability to perform rapidly alternating agonistic-antagonistic movements
- Rapid alternating movement test: the patient is unable to rapidly "screw" in an imaginary light bulb simultaneously with both hands (slow, uncoordinated movements)
- Rebound phenomenon (Stewart-Holmes sign)
- The patient bends their arm at the elbow, resisting the examiner's pull on the forearm; sudden release of the arm by the examiner results in an overshooting movement.
- Indicates impaired coordination between muscular agonists and antagonists
- Pronator drift: Patients stretch supinated arms out in front of them at shoulder level; the arm ipsilateral to the lesion will pronate and drift upwards.
- Dysarthria (scanning speech): words are broken down into separate syllables and spoken with varying force
- Oculomotor dysfunction, including nystagmus
- In acute cerebellar hemorrhage: occipital headache, neck stiffness, vomiting; , nystagmus; , gait ataxia
- Muscular hypotonia
The localization of symptoms offers important diagnostic clues! Unilateral abnormalities in ocular movements, ataxia, and posture indicate a cerebellar lesion on the ipsilateral side!
Cerebellar syndromes are primarily a clinical diagnosis, based especially on the evaluation of posture, gait, and movements. Imaging tests and laboratory studies confirm the diagnosis.
- Neuroimaging (CT/MRI): indicated to rule out infarction, hemorrhage, tumors, edema
- Laboratory testing: complete blood cell count; electrolytes, vitamin B12 levels, vitamin B1 levels
- Genetic testing: if other diagnostic tests are negative or inconclusive
|Differential diagnoses of ataxia|
|Cerebellar ataxia||Sensory (spinal) ataxia||Vestibular ataxia|
|Clinical features|| || |
|(tests proprioception and vestibular function)|| || || |
|(tests vestibular and cerebellar function)|| || || |
The differential diagnoses listed here are not exhaustive.