Abnormalities of nerve conduction studies in myotonic dystrophy type 1: Primary involvement of nerves or incidental coexistence?

Peripheral nerve involvement in myotonic dystrophy type 2 – similar or different than in myotonic dystrophy type 1?

“…The most common abnormal findings were decreased CV along the whole ulnar and median nerve (not only within entrapment sites) as well as increased latency of the F-wave in the peroneal nerve. Similar results were reported in a study by Bae et al [17] in which 8 of 18 patients had abnormal nerve conduction study findings (most common were abnormal peroneal motor nerve conduction and the H-reflex) but a sensorimotor axonal polyneuropathy was diagnosed only in one patient. Bae et al [17] suggested that some minimal abnormalities found in conduction studies (which did not allow the diagnosis of PNP) could also be explained by technical factors (e.g., muscle wasting) or concomitant conditions such as lumbosacral polyradiculopathy.…”

“…Some authors supported the notion of primary peripheral nerve dysfunction in DM1 which is unrelated to glucose intolerance or other metabolic factors [14,16,17,20,29,37]. Studies performed in transgenic mice (DMSXL) also demonstrated the presence of motor neuropathy.…”

“…In a study by Dabby et al [33], neuropathy was found in 2 of 10 patients with genetically confirmed DM2, but the criteria for the diagnosis of PNP were not listed and the patient sample was very small. Some electrophysiological studies of DM1 suggest that the incidence of PNP ranges from 18% [17] to 45% [14], and on average is 20-30% [13,15,16]. In a recent study of 93 patients with DM1, Hermans et al [29] found evidence of PNP in 17% of patients using clearly defined electrophysiological criteria.…”

“…The issue of peripheral nerve involvement in DM1 is still a matter of debate. Although patients seldom complain of sensory symptoms, some authors described peripheral neuropathy [13][14][15][16][17][18] or abnormal results of peripheral nerve conduction studies [19][20][21][22] in patients with DM1. Other reports, however, indicate no primary peripheral nervous system involvement in DM1 [23][24][25][26].…”

Peripheral neuropathy in myotonic dystrophy type 1

“…Patients seldom report sensory symptoms such as numbness, paresthesias, or dysesthesias. While some authors reported impairment of peripheral nerve conduction ( Mongia and Lundervold, 1975 ; Panayiotopoulos and Scarpalezos, 1976 ; Olson et al, 1978 ; Roohi et al, 1981 ; Mechler et al, 1982 ; Rossi et al, 1983 ) or the presence of peripheral neuropathy (PNP) in DM1 patients ( Jamal et al, 1986 ; Logullo et al, 1992 ; Mondelli et al, 1993 ; Pfeilsticker et al, 2001 ; Bae et al, 2008 ) , others denied the existence of peripheral nerve involvement ( McComas et al, 1971 ; Caruso and Ferrannini, 1976 ; Messina et al, 1976 ; Pollock and Dyck, 1976 ; Gantelet et al, 2007 ) (Table 1). However, these previous studies have been limited by their small sample size and lack of uniform definitions of PNP.…”