|Year : 2020 | Volume
| Issue : 2 | Page : 223-226
Sensory nerve conduction study in patient of thyroid dysfunction in central India
Department of Physiology, Jawaharlal Nehru Medical College, Datta Meghe Institute of Medical Sciences (Deemed to be University), Sawangi (Meghe), Wardha, Maharashtra, India
|Date of Submission||24-Apr-2020|
|Date of Decision||30-Apr-2020|
|Date of Acceptance||10-May-2020|
|Date of Web Publication||21-Dec-2020|
Dr. Avinash Taksande
Department of Physiology, JNMC, Sawangi (M), Wardha, Maharashtra
Source of Support: None, Conflict of Interest: None
Introduction: Hypothyroidism is a endocrine disorder which results in neurological dysfunction. It also affects brain, peripheral nerves and muscular system. The neurologic manifestations, which may be noted incidently, occur in conjunction with the systemic features of the disease. Peripheral neuropathy occurs early in hypothyroidism and its detection is necessary for early diagnosis and treatment. Study aimed to know the sensory nerve conduction in patients of hypothyroidism and to compare sensory nerve conduction parameters in patients of hypothyroidism with normal healthy controls. Materials and Methods: Comparative study. Study Design: Total 100 subjects were taken in the study in the age group of 18–66 years. Out of 100 subjects 50 were diagnosed thyroid dysfunction patient and 50 subjects were healthy individual. Informed written consent was taken from all the subjects. Nerve conduction study consists of sensory nerve conduction study of Median, Ulnar and Sural nerves. In the department of Physiology. Electrophysiological parameters such as Sensory Nerve Action Potential amplitude and conduction velocity were evaluated. Results: It was found that sensory nerve action potential amplitude and conduction velocity were significantly reduced in median and ulnar nerves in cases as compared to controls. Conclusion: Nerve conduction study very effective test for early diagnosis of peripheral neuropathy in thyroid dysfunction.
Keywords: Hypothyroidism, nerve conduction study, sensory neuropathy
|How to cite this article:|
Taksande A. Sensory nerve conduction study in patient of thyroid dysfunction in central India. J Datta Meghe Inst Med Sci Univ 2020;15:223-6
| Introduction|| |
Hypothyroidism is a clinical disorder due to the deficiency of thyroid hormone. This hormone is a key regulator of cellular metabolism in our body. This deficient state is estimated to affect 3.8%–4.6% of general population. Hypothyroid state is usually asymptomatic symptoms in the early phase while associated with number of symptoms later affecting skin, heart, endocrine, brain and nerves. Peripheral polyneuropathy a progressive nerve disorder to become chronic disability may be due to the defect in axons, nerve cell body or myelin sheath. It usually manifests as numbness, parasethesia, weakness, fatigue, loss of reflexes, loss of vibration. Hyperthyroidism is less commonly associated with neuromuscular disorders and polyneuropathy is a relatively rare complication of hyperthyroidism.
Electrophysiological assessment of sensory-motor nerve action potential Sensory Nerve Action Potential (SNAP), compound motor action potential amplitudes, distal motor latency, sensory nerve conduction velocity, and motor nerve conduction velocity help to characterize and quantify the sensory and motor functions in the peripheral nerves.,
The purpose of study is evaluating functional changes in the peripheral nervous system in thyroid dysfunction patients.
This study aims to assess the electrophysiological functions of the sensory nerves in cases of clinically manifest as thyroid dysfunction.
1. To assess sensory nerve conduction study in thyroid dysfunction patients.
| Materials and Methods|| |
The study was conducted on thyroid dysfunction patients attending the outpatient department coming for treatment. Control group was normal (healthy) controls.
Type of study
Total 100 subjects were taken in the study in the age group of 18–66 years. Out of 100 subjects 50 were diagnosed thyroid dysfunction patient and 50 subjects were healthy individual. Informed written consent was taken from all the subjects. Nerve conduction study consists of sensory nerve conduction study of Median, Ulnar and Sural nerves.
Parameters such as Sensory Nerve Action Potential (SNAP) amplitude and conduction velocity for sensory nerves were recorded and analyzed.
Sensory nerve conduction study
Antidromic Sensory conduction study involved stimulation of sensory nerves proximally and recording SNAPs with electrodes placed distally over the dermatomic distribution. Distance between active electrode and cathode of stimulator will divide automatically by onset latency to give sensory conduction velocity antidromic study will be done using ring electrode. Ring electrode will be placed on index finger for Median nerve, on little finger for ulnar nerve and surface disc electrode will be placed below lateral malleolus of ankle of foot for Sural nerve. In all cases cathode and anode were 3 cm apart.
For upper and lower limbs, duration will 100 μs, sweep speed 2 ms/D and filter will be between 20 Hz to 3 KHz.
Diagnosed case of thyroid dysfunction by expert physician.
Exclusion criteria for participation in this study includes
- Subjects with known causes of neuropathy (diabetic mellitus, leprosy)
- History of limb injuries or trauma
- Cardiac pacemakers, cardiac pathology
- Current pregnancy, malignancy
- Neuromuscular transmission disorders, myopathy
Values were analyzed in the form of mean and standard deviation, P < 0.05 was taken as statistically significant.
As it is noninvasive study there will be no harm to the study subjects.
Nerve conduction study will be performed by using the medicaid machine.
Ethical approval for this study (DMIMS(DU)/IEC/2014-15/987) was provided by the Ethical Committee of Datta Meghe Institute of Medical Sciences (Deemed to be University) on 15/12/2014.
| Results|| |
Mean age of the participants was 35.5 years. There was no statistically significant difference between control and cases of hypothyroidism in age [Table 1] and shows significant changes in male and female [Table 2].
Sensory nerve conduction abnormalities were found in patients of hypothyroidism as compared to controls. In upper limb the median and ulnar nerves amplitude and nerve conduction velocity were significantly reduced in cases as compared to controls on right and left side [Table 3] and [Table 4]. In lower limbs, the sural nerve the bilateral SNAP amplitude and right conduction velocity was not significant and conduction velocity significantly reduced in cases as compared to controls on the left side [Table 5].
| Discussion|| |
SNAP amplitudes and cardiovascular (CV) were significantly reduced in cases as compared to controls in bilateral median and ulnar nerves. CV was significantly reduced in cases as compared to controls in left sural nerve (P < 0.05). Rao et al. found reduction of amplitude for median sensory nerves whereas Fincham and Cape found it for median and ulnar sensory nerves. Our data comprising of outpatients with thyroid dysfunction confirms the assumption that demyelinating polyneuropathy in hypothyroidism is commonly encountered. The nerve conduction study findings correlate well with those in literature. Axonal degeneration has been reported both electrophysiologically and pathologically. Previous studies have shown a reduction in amplitude and mild slowing of sensory and motor conduction velocity consistent with presence of axonal polyneuropathy.
Peripheral nervous system dysfunction is an important outcome of thyroid hormone deficiency. In newly diagnosed cases symptoms and signs of mixed neuropathy may predominate initially. The symptoms of peripheral nerve involvement are a fairly sensitive predictor of polyneuropathy. Majority of these cases would have gone unnoticed, had only a clinical examination been done. Often polyneuropathy in hypothyroidism is mild and rarely it could be a subclinical entity.
Thyroid hormone is also known to influence the synthesis is of protein and the production of enzyme and of myelin sheath., Myelin synthesis is an important factor in determining the speed of impulse transmission along the nerve length., Disturbed myelin synthesis during acute hypothyroidism may be the cause for demyelinating peripheral neuropathy in hypothyroid patients. Hormonal and metabolic changes associated with hypothyroidism are responsible for the electrophysiological changes in the form of abnormal peripheral nerve conduction study which occurs early in the disease course.
Thyroid hormone seems to increase ATPase activity and consequently, the activity of the ATP-dependent Na+/K + pump. The increase in ATPase activity would be associated with an increase of ATP transport through the mitochondrial membranes. In hypothyroidism, the ATP deficiency and the reduced activity of the ATPase enzyme induces a decrease in Na+/K+ pump activity, with consequent alterations of pump dependent axonal transport. This leads to axonal degeneration and peripheral neuropathy in hypothyroidism.
The mucinous infiltrations found in the peripheral nerves could interfere mechanically with metabolic exchange of nutrients and catabolic products to and from the neuron resulting in entrapment neuropathy in hypothyroidism. The deposition of mucopolysaccharide or the myxomatous tissue around the peripheral nerves may also lead to its compression and thereby results in swelling and degeneration of those nerves leading to peripheral neuropathy in hypothyroidism.,,,,,,
| Conclusion|| |
Our study shows that hormonal changes which are responsible for electrophysiological changes may occur thyroid disease. Hence, we suggest performing nerve conduction tests in hypothyroid patients early in the course of the disease, as a routine even in those asymptomatic for nervous complaints, to minimize structural damage and disability.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]