Spinocerebellar degeneration with slow eye movements (SDSEM) is an extremely rare autosomal recessive disorder characterized by hereditary ataxia with slow eye movements. The condition has certain associated features, including progressive intellectual impairment, extra-pyrimidal dysfunction, peripheral neuropathy, and skeletal abnormalities. Although very similar to the Wadia Swami syndrome, SDSEM differs from the former in its relatively slow progression and recessive mode of inheritance.
Al-Din et al. (1994) described two consanguineous Arab families with SDESM. The ataxia in these cases presented within the first decade of life, and was severely disabling. A spectrum of eye movement abnormalities, psychomotor retardation, and sensory neuropathy were also involved. Brain MRI revealed significant cerebellar and brainstem atrophy.
[See: Palestine > Al-Din et al., 1990].
A consanguineous family with SDESM was first described by Al-Din et al. (1990). Affected members in this family of Palestinian origin, but residing in Kuwait, showed progressive intellectual impairment and extra-pyramidal dysfunction, peripheral neuropathy, and skeletal abnormalities. Non-specific mitochondrial abnormalities were revealed in the muscle biopsy. The pedigree showed three affected males and 3 affected females in two sibships, both with consanguineous parents and at least one common ancestral couple. Al-Din et al. (1990) thought that the disorder was similar to the olivopontocerebellar degeneration, with the added degeneration of selected tracts and nuclei in the mesencephalon and rostral structures. The progress of the disorder was slower than that in the Wadia-Swami syndrome; a severe disability was reached in 10-15 years, but even at that stage the main disability was that of gait and patients managed to live with minimal help except for walking.