Electrophysiological features of late-onset transthyretin Met30 familial amyloid polyneuropathy unrelated to endemic foci.

Abstract

BACKGROUND:

Through the development of gene diagnostic techniques, late-onset transthyretin Met30-associated familial amyloid polyneuropathy (FAP TTR Met30) has been shown to be more prevalent than is generally believed.

OBJECTIVE:

To examine the electrophysiological features of late-onset FAP TTR Met30 unrelated to endemic foci.

METHODS:

Nerve conduction findings in 44 cases with an onset of more than 50 years of age in a non-endemic area were assessed and compared with findings from 21 earlier-onset cases related to endemic foci.

RESULTS:

The extent of the reduction of the compound muscle action potential and, especially, the sensory nerve action potential was more profound in the late-onset group even when the decline of these indices with aging in normal control subjects was taken into account. The feature of predominant lower-limb involvement seemed to be more conspicuous in the late-onset group. Electrophysiological indices tended to be aggravated as the duration of neuropathic symptoms increased in the early-onset group, while most of these indices in the lateonset group did not show this correlation. A slowing of conduction velocity and a prolongation of distal latency, which suggests demyelination, were conspicuous in some patients. Pathologically, a predominant loss of small-fibers was not conspicuous in sural nerve biopsy specimens from late-onset patients. Large myelinated fiber density showed a negative correlation with the disease duration in early-onset cases, but not in late-onset cases.

CONCLUSIONS:

Electrophysiological differences between late- and early-onset cases were present, probably reflecting the different underlying pathogenic mechanisms of neuropathy. The demyelinating feature does not exclude the possibility of this disease.

• Authors: Haruki Koike, Yuichi Kawagashira, Masahiro Iijima, Masahiko Yamamoto, Naoki Hattori, Fumiaki Tanaka, Masaaki Hirayama, Yukio Ando, Shu-ichi Ikeda, Gen Sobue
• Journal: Journal of neurology (J Neurol) Vol. 255 Issue 10 Pg. 1526-33 (Oct 2008) ISSN: 0340-5354 [Print] Germany
• PMID: 18821042 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Amyloid
• Prealbumin
• amyloid prealbumin

Topics

• Action Potentials
• Adult
• Age Factors
• Age of Onset
• Aged
• Amyloid (genetics)
• Amyloid Neuropathies, Familial (epidemiology, physiopathology)
• Female
• Humans
• Leg (innervation, physiopathology)
• Male
• Median Nerve (physiopathology)
• Middle Aged
• Nerve Fibers, Myelinated (pathology)
• Neural Conduction
• Prealbumin (genetics)
• Sensory Receptor Cells (pathology, physiology)
• Sural Nerve (pathology)
• Tibial Nerve (physiopathology)