Electrodiagnostic Findings of Median Nerve Motor and Sensory Conduction in Neurological Asymptomatic Newly Diagnosed Patients with Hypothyroidism

Abstract

BACKGROUND: The influence/impact of thyroid hormones on peripheral nervous system has still not been thoroughly/substantially studied/examined. Neurographic studies, which measure motor and sensory nerve conduction along with F-wave, have an important role in diagnosing diseases of the peripheral nerves since electrophysiological sings of neuropathy can be detected even in subclinical state/cases.

AIM: The aims of this study were to assess the neurophysiological parameters of the median nerve by electrodiagnostic measurements using electromyoneurogaphy (EMNG) in the region of radiocarpal joint in patients with newly diagnosed and medically untreated primary hypothyroidism who had no symptoms and signs of peripheral nerve damage/injury/lesion. Furthermore, it was our aim to make an insight of the possible early detection of the latent damage of peripheral nervous system in untreated hypothyroidism.

MATERIAL AND METHODS: This was a prospective clinical study that comprised 78 subjects/patients according to inclusion criteria, divided into two groups: one with primary hypothyroidism and the other group involving euthyroid subjects. Thyroid status was examined in each subject; anthropometric parameters were analyzed, and electromyoneurographic imaging (EMNG) of hand median nerve was realized.

RESULTS: Of the total number of 78 subjects included in the study, 58 (74.36%) had hypothyroidism and 20 were euthyroid subjects (25.64%). The calculated mean levels of thyroid status parameters in hypothyroid patients, TSH, aTPO and FT4, were 6.19±1.85 mIU/L, 872.22±296.66 U/mL and 0.78±0.11 ng/dL, respectively. In euthyroid patients, the mean levels of TSH, aTPO and FT4 were 0.27±0.08 mIU/L, 31.2071±5.65 U/mL and 1.31±0.25 ng/dL, respectively. Statistically significant differences were obtained between hypothyroid and euthyroid subjects regarding: age (p=0.0147, r=0.3239), body weight (p=0.0441, r= -0.531), body mass index (p=0.0050, r= -0.301), WHO classification for BMI (p=0.0032, r= -0.250), TSH (p<0.0001, r=-0.309), aTPO (p<0.0001, r=0.5554) and FT4 (p<0.0001, r= -0.317). In the group of 58 hypothyroid subjects, 38 (65.52%) were women and 20 (34.48%) were men. A strong correlation and significant statistical difference were registered in EMNG pathological findings in patients with pathologic BMI and with mild predilection for the sensory part of the median nerve. Of the 58 hypothyroid patients, EMNG pathologic findings were present in 18 that, in terms of their features, indicated a distal lesion of the median nerve. These 18 subjects had an increased body mass index (30.83±5.65 kg/m2).

CONCLUSIONS: Discovery, definition and explanation of etiopathogenic nodes in peripheral nervous system diseases will require extensive and multidisciplinary strategies in the next decades. These complex conditions, in our opinion, will claim a steady/a step-by-step/ approach to the problems, as well as consistency and symmetry in the design and methodology of the research procedures.