X-LINKED ADRENOLEUKODYSTROPHY PRESENTING AS NEUROLOGICALLY PURE FAMILIAL SPASTIC PARAPARESIS

The familial spastic paraplegias (FSPs) are heterogeneous neurologic d isorders that are known to occur clinically as ''pure'' or ''complicat ed'' forms. Although some of the complicated FSPs have been linked to specific metabolic defects, the pure forms of this disorder remain idi opathic and are considered to be primary system degenerations. We repo rt the case of a 28-year-old man who has evidenced a neurologically pu re spastic paraparesis since age twenty-five. Consistent with this dia gnosis were the findings of magnetic resonance imaging, which revealed atrophy of the thoracic spinal cord without evidence for white matter disease in the cerebrum, cerebellum, or brainstem. His 32-year-old br other has also evidenced progressive spastic paraparesis since age 30, but his case is confounded by a severe head injury at age 24 that cau sed a skull fracture and a focal demyelinating lesion of the right fro ntal lobe. Both patients have had hypogonadism, requiring treatment wi th testosterone, since age 20. Measurement of plasma levels of very lo ng-chain fatty acids (VLCFA) revealed that both brothers had concentra tions diagnostic of adrenoleukodystrophy; their mother had plasma VLCF A levels in the heterozygous range. We conclude that neurologically pu re FSP can be an early manifestation of adrenoleukodystrophy and that levels df plasma VLCFA should be determined for all cases of FSP in wh ich X-linked inheritance appears tenable. These considerations may hav e bearing on the ongoing linkage studies for these disorders.