From the Research
Electromyography (EMG) findings in patients with beriberi typically show patterns consistent with axonal polyneuropathy, including reduced amplitude of compound muscle action potentials (CMAPs) and sensory nerve action potentials (SNAPs), with relatively preserved conduction velocities in the early stages of the disease. These findings are supported by the most recent study on the topic, which highlights the importance of considering thiamine deficiency in malnourished patients presenting with symptoms and signs of peripheral neuropathy 1. The EMG findings in beriberi can be summarized as follows:
- Reduced amplitude of CMAPs and SNAPs
- Relatively preserved conduction velocities in the early stages of the disease
- Evidence of denervation, including fibrillation potentials, positive sharp waves, and complex repetitive discharges in affected muscles
- Motor unit potentials often show increased duration and amplitude, reflecting the reinnervation process
- Recruitment patterns are typically reduced, indicating loss of functioning motor units
- In severe or chronic cases, EMG may reveal widespread denervation across multiple muscle groups, particularly in distal limb muscles
The severity of EMG abnormalities generally correlates with the clinical severity of the neuropathy and typically improves with thiamine supplementation, though complete recovery may take months depending on the extent of nerve damage 2. It is essential to note that axonal neuropathies, such as those seen in beriberi, can present with conduction failure that can be either reversible with prompt recovery or progress to axonal degeneration with poor outcome 2. Therefore, early diagnosis and treatment of thiamine deficiency are crucial to prevent long-term nerve damage and improve patient outcomes.