Cerebellar - Friedreich's Ataxia

 

Thank you for asking me for Harry (young male typically), who presented with difficulty walking / poor coordination.

 

On inspection, there is a broad-based ataxic gait (bilateral cerebellar signs on FA). The patient could/could not walk heel to toe, suggesting the presence/absence of a cerebellar pathology. The patient could/could not walk on their toes (S1), and the heels (foot drop, L4 or L5). Romberg’s sign was negative with difficult standing with the eyes open suggesting cerebellar disease. (eyes closed - posterior columns, eyes open - cerebellar).

 

There was kyphoscoliosis.

 

Can get upper motor neuron signs (mainly spasticity) in the limbs as the disease progresses

 

On inspection of the legs, there was pes cavus and hammer toe. There evidence of distal muscle wasting, but no fasciculations. There was not muscle tenderness. Tone was normal/reduced in the knee and ankle (normally normal or reduced), and there was/was not clonus.

 

Power was reduced symmetrically in a pyramidal distribution with __/5 power on the left leg, and __/5 power on the right. Usually in feet and legs first, following by hands and arms.

 

Reflexes were reduced/absent in the knee and ankle (deep tendon reflexes lost in most). Plantar response was upgoing. (Combination of pyramidal UMN weakness and peripheral neuropathy).

 

Coordination was impaired bilaterally on heel-shin, toe-finger and foot tapping assessment. (Ask them to lift the leg in an arc to make it more difficult if deficit is subtle).

 

Sensation was reduced symmetrically in a stocking distribution with reduced proprioception and vibration, indicating posterior column dysfunction. Pinprick was intact/reduced.

 

On examination of the face, there was bilateral horizontal nystagmus with the fast component towards left/right (fast towards the side of the lesion). There was/was not broken pursuit, and normal/hypometric/hypermetric saccades (hypo- is undershoot, hyper- is overshoot).

 

The speech was slurred and a jerky, explosive, staccato character (ask to say Hippopotamus, Constitution, West Register Street).

 

In the arms, there was/was not arm drift.

 

Tone was increased (get upper motor neuron signs in FA). 

 

There was impaired finger-nose testing with dysmetria and an intention tremor on the bilaterally. There was dysdiadochokinesis.

 

There was/was not rebound phenomenon in the arms.

 

On sitting up over the edge of the bed, there was/was not evidence of truncal ataxia. Pendular knee jerks were present/absent.

 

On further examination:

• There were/were not signs of cardiomyopathy

• There was/was not evidence of diabetes mellitus.

• There was optic atrophy

• Assess for dysphagia, reduced visual acuity, hearing loss, and cognitive assessment

 

In summary, my findings are consistent with bilateral cerebellar deficits and features most likely suggestive of Friedreich’s ataxia.

 

Differentials include:

• Bilateral

  • MS

  • Friedreich’s ataxia

  • Alcohol

  • Drugs

  • Hypothyroid

  • Space-occupying (large)

  • Trauma

  • Paraneoplastic

• Unilateral:

  • A space-occupying lesion

  • Previous infarcts

  • Multiple sclerosis

  • Trauma

• Differentials for spastic and ataxic paraparesis:

 

 

Differentials of a spastic paraparesis include:

• Hereditary spastic paraparesis (caused by length dependent degeneration of the corticospinal tract)

• Hereditary ataxias with spasticity such as certain spinocerebellar ataxias and Friedreich’s ataxia

• Spinal cord lesions

  • Compression from tumours or abscess

  • Vascular malformations

  • Subacute combined degeneration (weakness, sensory ataxia, spasticity, paraesthesias)

• Demyelinating disorders such as:

  • Progressive MS

  • Neuromyelitis optica

• Motor neuron disease

 

Differentials of spastic and absent reflexes but extensor plantar response:

• FA

• Adrenoleukodystrophy

• Subacute combined degeneration - ankle reflexes usually absent

• Neurosyphillis

• Dual pathology

 

I would like to proceed from here by:

• Exclude other cause with an MRI

• Confirm the diagnosis with genetic testing

• Screen for complications with:

  • ECG - cardiomyopathy

  • HbA1c - diabetes