Familial Amyloid Polyneuropathy and Liver Transplantation
December 1, 1997 2 minutes read
Familial Amyloid Polyneuropathy and Liver Transplantation
ABSTRACT & COMMENTARY
Source: Ikeda S, et al. Peripheral nerves regenerated in familial amyloid polyneuropathy after liver transplantation. Ann Intern Med 1997;127:618-620.
Several kinds of amyloidosis can affect the nervous system. Most common is the beta-amyloid that comprises the Alzheimer plaque as well as the similar amyloid that causes cerebral vascular amyloidosis. Far less frequent than the above variant is an autosomal dominant form of Familial Amyloid Polyneuropathies (FAP), of which Type I, called transthyretin amyloidosis, affects predominantly autonomic and small peripheral sensorimotor fibers. Onset is usually in the third or fourth decade and, if not treated, severe limitations or death follow within 10-15 years (see Bosch, Mitsumoto. In: Bradley, et al (eds). Neurology in Clinical Practice, 2nd ed. Boston: Butterworth-Heinemann; 1996:1906-1907). The specific nerve defect reflects a mutation of a gene located on chromosome 18q11.2-q12.1 that normally generates the protein that transports thyroxine and retinol-binding protein. The result leads to amyloid deposits between nerve fibers and, by a poorly understood process, eventually produces degeneration of the small sensory and autonomic nerves. Most transthyretin is generated by the liver, as is its damaging mutation. Improvement from the disease following hepatic transplants has been reported.
Against the above background, Ikeda et al describe the results of a partial liver transplant to a 31-year-old woman with progressing FAP. Preoperatively, she had shown prominent neurologic impairment involving impaired small-fiber sensory functions producing neuropathy in the lower extremities plus orthostatic hypotension and bowel/bladder dysfunction. Sural nerve biopsies were obtained from the left (before) and right (3 years after) transplantation. Histograms of total nerves and diameter of myelinated nerves were constructed for each examination. The patient successfully received a partial liver transplantation obtained from a sister’s liver.
Post-operatively, the patient’s autonomic insufficiencies gradually disappeared, as did her neuropathy. She returned to her pre-illness baseline by one year and by three years had no residual symptoms of her FAP. Motor and sensory nerve conduction both improved. Sural nerve biopsy showed both a 3.6-fold increase in number of fibers per micrometer and an increase in diameter in myelinated fibers.
COMMENTARY
The authors report that liver transplants into more than 150 patients world-wide have shown that transthyretin mutants disappear early and disease worsening stops. How often neurologic changes occur is unclear, although autonomic impairments are said to improve more than somatic ones. Bergethon et al (Neurology 1996;47:944-951) emphasize the considerable general and neurologic improvement that followed liver transplantation in nine patients. Neurology Alert apologizes for overlooking their important contribution at the time of its publication. fp
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