Cerebellar disease

Question 1

What is the role of cerebellum

Answer 1

This part of the central nervous system is primarily focussed on the coordination of movement
- therefore disorders of this region do not cause paresis (weakness) or paralysis
- but incoordination of movement and changes in posture

Question 2

What are the two main functional regions of the cerebellum

Answer 2

The cerebellum is divided into two lateral hemispheres, with a strip of tissue running down the middle, called the vermis

The two main functional regions are:
- the large body of the cerebellum (divided into rostral and caudal lobes)
- the smaller flocculonodular lobe (tucked up underneath the ventral aspect of the cerebellum)

Question 3

How is the cerebellum connected to the brainstem

Answer 3

The cerebellum is attached to the brainstem via three cords of neural tissue on each side, known as the cerebellar peduncles
- the rostral cerebellar peduncle connects the midbrain to the cerebellum and contains many of the efferent pathways
- the middle cerebellar peduncle connects the cerebellum with the pons and contains only afferent pathways
- the caudal cerebellar peduncle connects the spinal cord and medulla to the cerebellum and contains afferent pathways from the limbs, trunk, and neck and vestibulocerebellar axons

Question 4

What is the most frequent presentation for cerebellar diseases

Answer 4

Usually, diseases of the cerebellum are diffuse and cause bilaterally symmetrical signs
- however unilateral lesions can occur resulting in ipsilateral signs

Question 5

What is the main differential for lesions of the cerebellum

Answer 5

Lesions of the cerebellum cause hypermetria of movement producing “bursts” of exaggerated movement of normal strength

This needs to be differentiated from lesions within the cervical spinal cord (C1-C5) causing hypermetric upper motor neuron signs to all four limbs in which the gait tends to be described more as over-reaching or “floatting”

Question 6

What are the clinical signs of cerebellar dysfunction

Answer 6

Spastic, jerky limb movements when walking or hopping, overshooting food bowls, …

No loss of strength (muscle tone may be increased)

Broad-based stance at rest

Swaying of trunk while walking and standing (truncal ataxia, also known as titubation)

May see tremoring upon initiation of movement (intention tremors) that disappear at rest

May have fine jerky movements of eyes

Menace deficit (despite normal vision and facial nerve function) ipsilateral to the lesion)

May see anisocoria (slight dilation of pupil on opposite side to lesion with normal PLR)

May occasionally observed opisthotonos and vestibular signs
- severe lesions, especially involving the rostral cerebellar lobe may result in decerebellate rigidity

Question 7

What are your main differentials for cerebellar signs

Answer 7

Congenital
- panleukopenia virus infection in neonates
- storage diseases
- hereditary cerebellar anomalies
- cerebellar degeneration (abiotrophy)

Infectious
- FIP
- toxoplasmosis
- cryptococcosis
- bacterial

Neoplasia
- primary
- metastatic

Toxins
- Metronidazole

Vascular
- infarction (e.g., thrombus, Cuterebra larvae)
- hemorrhage