Mitochondrial Disorders May Mimic Amyotrophic Lateral Sclerosis at Onset

Area of Science:

• Neurology
• Mitochondrial Biology
• Neurodegenerative Diseases

Background:

• Amyotrophic lateral sclerosis (ALS) and mitochondrial disorders (MID) share overlapping symptoms.
• Mitochondrial multiple organ dysfunction syndrome (MIMODS) can complicate diagnosis, especially in mild cases.
• Accurate differentiation is vital for appropriate patient management.

Purpose of the Study:

• To highlight the diagnostic challenges in differentiating MID from ALS.
• To present a case study illustrating the mimicry of ALS by MID.
• To emphasize the importance of considering MIDs in progressive neurological conditions.

Main Methods:

• Case report of a 48-year-old male with progressive neurological symptoms.
• Electrophysiological investigations initially suggesting ALS.
• Muscle biopsy revealing morphological features of MID and a combined complex-II/III defect.
• Longitudinal nerve conduction studies over a decade.

Main Results:

• The patient initially diagnosed with ALS showed features mimicking the disease.
• Muscle biopsy confirmed a mitochondrial disorder with a specific enzyme defect (complex II/III).
• The condition evolved from a seemingly isolated neurological issue to multi-organ involvement.
• Bulbar involvement was observed, a feature sometimes seen in both ALS and specific MIDs.

Conclusions:

• Mitochondrial disorders can present as amyotrophic lateral sclerosis, particularly in early stages.
• Long-term observation and specific diagnostic tests like muscle biopsy are essential for correct diagnosis.
• Combined complex II/III defects may manifest with bulbar symptoms, further complicating the differential diagnosis with ALS.