suspected of having a degenerative disease but without family history
or clinical signs suggestive of a particular degenerative disease should
have their urine tested for sialic acid, glycoproteins, mucopolysaccharides,
and N-acetylaspartate and arylsulfatase activity. Blood should be tested
for very-long-chain fatty acids, N-acetylaspartate, copper, and ceruloplasmins,
and an MRI of the brain should be performed. Enzyme studies in leukocytes
and fibroblasts, and biopsies of nerve, muscle, skin, or liver should
be done when a specific disease is suspected. There is no specific treatment
for any of these disorders. The diagnosis of a degenerative disorder should
be followed by genetic counseling.
Cerebellar lesions produce
hypotonia with decreased or normal dynamic tone (Figure 115.1).
Hypotonia and decreased or normal dynamic tone occur because damaged cerebellar
neurons alter the alpha motor neurons indirectly by their influence on
brain and brainstem structures.
Salient features of cerebellar hypotonia. Arrow indicates the site of
dysfunction (cerebellum). US: brain ultrasound; CT: computerized
tomography; MRI: magnetic resonance imaging.