Mitochondriopathy as a differential diagnosis of amyotrophic lateral sclerosis

Amyotroph Lateral Scler Other Motor Neuron Disord. 2002 Dec;3(4):219-24. doi: 10.1080/146608202760839008.


Objectives: To assess how often mitochondrial myopathy (MMP) mimics amyotrophic lateral sclerosis (ALS) and the phenotypic similarities and differences between these two disorders.

Methods: Records of 123 MMP patients and 59 ALS patients, diagnosed during five years (1996-2000), were retrospectively evaluated.

Results: Re-evaluation revealed that 8 patients, initially diagnosed as ALS had actually MMP (13.6%). Among the MMP patients, 6.5% were initially misdiagnosed as ALS. None of the MMP patients actually had ALS. Common features of ALS and MMP were weakness, wasting, upper motor neurone signs, bulbar abnormalities, and a neurogenic EMG. Features differentiating MMP from ALS were ptosis, sensory disturbances, multi-system involvement, slowly progressive disease course, abnormal lactate stress test, histological and biochemical abnormalities, and mtDNA analysis.

Conclusions: In a small number of cases MMP may clinically and electrophysiologically mimic ALS, particularly in the early stages of the disease. Patients with suspected ALS, but slow progression and multi-organ involvement, should undergo lactate stress testing and muscle biopsy. ALS should be diagnosed only if MMP has been excluded.

Publication types

  • Comparative Study

MeSH terms

  • Action Potentials / physiology
  • Adult
  • Aged
  • Amyotrophic Lateral Sclerosis / blood
  • Amyotrophic Lateral Sclerosis / diagnosis*
  • Diagnosis, Differential
  • Electromyography / methods
  • Female
  • Humans
  • Lactic Acid / blood
  • Male
  • Middle Aged
  • Mitochondrial Myopathies / blood
  • Mitochondrial Myopathies / diagnosis*
  • Muscle, Skeletal / physiopathology
  • Neurologic Examination
  • Retrospective Studies


  • Lactic Acid