Distal myopathy in nephropathic cystinosis

Area of Science:

• Nephrology
• Neurology
• Genetics

Background:

• Nephropathic cystinosis is a multisystemic disorder with various organ complications.
• Distal myopathy, a known complication, affects approximately 24% of patients.
• Previous studies have highlighted the prevalence and clinical description of distal myopathy in this condition.

Purpose of the Study:

• To investigate the subclinical presence and characteristics of myopathy in patients with nephropathic cystinosis using neurophysiological techniques.
• To determine the extent of myopathy, particularly in distal muscles, even in the absence of reported muscle weakness.

Main Methods:

• Neurophysiological assessment including electromyography (EMG) was performed on seven patients with nephropathic cystinosis.
• EMG data was analyzed to detect signs of myopathy, focusing on distal muscle involvement.
• Motor and sensory nerve conduction studies were conducted to evaluate peripheral nerve function.

Main Results:

• All seven patients exhibited electromyography signs of myopathy, more pronounced in distal muscles.
• Only two patients reported subjective distal muscle weakness.
• Motor and sensory nerve conduction parameters remained within normal limits across all participants.

Conclusions:

• Distal myopathy is a common finding in nephropathic cystinosis, often subclinical and detectable through EMG.
• Neurophysiological assessment is essential for identifying myopathy in these patients, irrespective of clinical symptoms.
• Cystine-depleting therapy with cysteamine should be considered for all patients, and its impact on myopathy warrants further investigation.