Infantile-Onset Spinocerebellar Ataxia (IOSCA)

Inherited spinocerebellar ataxia with onset usually in the first 2 years of life. Clinical features include severe muscle hypotonia and atrophy, progressive changes in sensory nerve conduction (polyneuropathy), and seizure activity.

OHAHA Syndrome (Ophthalmoplegia, Hypacusis, Ataxia, Hypotonia, and Athetosis Syndrome); Infantile Spinocerebellar Ataxia with Sensory Neuropathy. Some researchers also use the term Spinocerebellar Ataxia (SCA) type 8 for this disease; however, this term has not been uniformly accepted.

Extremely rare, but more frequent in the Finnish population. The Finnish form of infantile-onset spinocerebellar ataxia (IOSCA) presents with slower progressive symptoms with clumsiness and loss of ability to walk as first manifestation. It does not share the same gene locus as OHAHA. It is an autosomal recessive inherited form of spinocerebellar ataxia with the mutation linked to 10q24.

Slowly progressive clinical symptoms appear usually between the ages of 10 and 24 months in previously healthy infants. The first symptoms are usually clumsiness and loss of the ability to walk. Ataxia, athetosis, and muscle hypotonia with loss of deep tendon reflexes, ophthalmoplegia with only convergence persisting, and hearing loss can be discovered on clinical examination. A polyneuropathy with profound decrease in sensory nerve conduction velocities and progressive loss of myelinated fibers in sural nerve biopsies may develop by adolescence. Involvement of the vestibular organ can markedly disturb the balance and may be present at the onset of symptoms. Some patients show abnormal background activity on the EEG with advancing age, and seizures (status epilepticus) have been described. Neuroradiologic investigation reveals cerebellar atrophy as the main cause of ataxia.

Proper evaluation of the extent of muscle hypotonia must be obtained. Seizure medication must be maintained. An anesthesia consultation is recommended before elective surgery.

As the disease progresses, nerve stimulation becomes technically more difficult, on the one hand making nerve location and regional anesthesia more unreliable and on the other hand requiring reduced concentration of local anesthetic solutions to produce a sufficient nerve blockade. Depending on the progress of the disease, monitoring of muscle relaxation may be difficult secondary to polyneuropathy.

Succinylcholine is best avoided because these patients may show increased sensitivity and hyperkalemic response. Chronic antiseizure medication can lead to hepatic enzyme induction and therefore affect the hepatic metabolism of other drugs.

Pagon Bird Detter Syndrome: X-linked recessive condition characterized by nonprogressive cerebellar ataxia, hyperreflexia, clonus, hypochromic microcytic anemia, ringed sideroblasts on bone marrow examination, and onset in early childhood. Believed to be caused by mutations in the adenosine triphosphate-binding cassette, subfamily B, member 7 gene.