Autosomal Recessive Spastic Ataxia of Charlevoix Saguenay; Spastic Ataxia of Charlevoix-Saguenay; ARSACS

Charlevoix-Saguenay Spastic Ataxia is a rare autosomal recessive disorder first described in families from the Charlevoix-Saguenay area of Quebec, Canada but rare cases have been reported world-wide. Clinical findings include cerebellar ataxia, spasticity, and peripheral nerve involvement with sensory loss and weakness. It is caused by mutations in SACS gene with results in an unstable sacsin protein, which is thought to impair organization of neurofilaments. The abnormal mutation must be present in both parents who are carriers and not affected. Diagnosis is suspected on clinical history and findings and is confirmed by genetic testing.

Diagnostic testing: A diagnosis of Charlevoix-Saguenay Spastic Ataxia is established by:

• •

  Clinical history and physical examination;

• •

  MRI and CT scans revealing atrophy of the upper cerebellar vermis and cervical spinal cord;

• •

  Signs of both axonal and demyelinating neuropathy by EMG/NCV;

• •

  Ophthalmological examination; and

• •

  Genetic testing for the detection of SACS mutations.

Physical findings: This disease is characterized by:

• •

  Early-onset ataxia with incoordination and difficulties with walking;

• •

  Spasticity;

• •

  Reduced sensation and weakness in the arms and legs (peripheral neuropathy);

• •

  Muscle wasting (amyotrophy);

• •

  Involuntary eye movements (nystagmus) and abnormal retinal pigmentation;

• •

  Difficulty swallowing (dysphagia) and speaking (dysarthria);

• •

  Finger and foot deformities;

• •

  Hypermyelination of the retinal nerve fibers;

• •

  Mitral valve prolapse;

• •

  High arched feet (pes cavus);

• •

  Scoliosis;

• •

  Hearing loss;

• •

  Recurrent seizures (epilepsy); and

• •

  Bladder dysfunction.

ICD-9: 334.1

ICD-10: G11.1

Usually, the gait difficulties are first noted as the child begins to walk between 12-18 months of age, with onset in the second year of life. This condition progresses slowly with a wheelchair required by thirties or forties.

There is no cure for this disorder and treatment is supportive. Treatment is symptomatic aiming towards controlling the spasticity and may include physiotherapy, pharmacotherapy and use of ankle-foot orthoses.

Suggested MER for Evaluation:

• •

  Clinical examination that describes the diagnostic features of the impairment; and

• •

  Genetic testing for SACS mutations.

REMARKS

Listing level findings must be present to meet listing.