Researchers have discovered that cutaneous silent periods (CSPs) in carriers of hereditary transthyretin amyloidosis are a possible early marker of nerve damage, according to a letter to the editor published in Neurological Sciences.
Hereditary transthyretin amyloidosis is an autosomal dominant disease that results in multisystemic pathology. Its therapeutic landscape has undergone tremendous change in recent years due to drugs that delay disease progression. The challenge now is to identify reliable biomarkers in presymptomatic carriers, allowing early treatment and hence giving patients the best chance of favorable clinical outcomes.
“The cutaneous silent period (CSP) is a spinal inhibitory reflex characterized by a brief period of suppression of voluntary muscular contraction following a painful electrical stimulus,” the authors of the study wrote. “The CSP is useful in assessing spinal cord disorders and to test the function of small myelinated fibers in axonal and demyelinating polyneuropathies.”
The authors of the study hence decided to clarify the role of the CSP as a potential biomarker in presymptomatic carriers. They recruited 17 patients who were presymptomatic carriers of hereditary transthyretin amyloidosis; all participants were clinically evaluated and underwent nerve conduction studies. The CSP was obtained by recording from the abductor brevis pollicis muscle of the dominant hand while the third digit was being stimulated.
Read more about hereditary transthyretin amyloidosis etiology
The results of the study demonstrated that this cohort of presymptomatic carriers displayed early alteration of CSPs and that small nerve fiber involvement was one of the first signs of hereditary transthyretin amyloidosis in patients with an early onset of the disease. This means that measuring CSPs may be a useful electrophysiological method for the investigation of small fiber function in hereditary transthyretin amyloidosis via standard electromyography.
“In conclusion, we suggest including CSP in regular neurophysiological follow-up of [hereditary transthyretin amyloidosis] pre-symptomatic carriers,” the authors of the study wrote. “Longitudinal studies on larger cohorts and analysis of CSP from other nerves (such as ulnar nerve or lower limbs nerves or from mixed nerves) will clarify the significance of our result.”
Luigetti M, Di Paolantonio A, Guglielmino V, Romano A. Cutaneous silent period in ATTRv carriers: a possible early marker of nerve damage? Neurol Sci. Published online August 9, 2022. doi:10.1007/s10072-022-06317-z