Treatment for mitochondrial disorders.
BACKGROUND
Mitochondrial respiratory chain disorders are the most prevalent group of inherited neurometabolic diseases. They present with central and peripheral neurological features usually in association with other organ involvement including the eye, the heart, the liver, and kidneys, diabetes mellitus and sensorineural deafness. Current treatment is largely supportive and the disorders progress relentlessly causing significant morbidity and premature death. Vitamin supplements, pharmacological agents and exercise therapy have been used in isolated cases and small clinical trials, but the efficacy of these interventions is unclear.


OBJECTIVE
To determine whether there is objective evidence to support the use of current treatments for mitochondrial disease.


METHODS
We searched the Cochrane Neuromuscular Disease Group trials register (searched September 2003), the Cochrane Central Register of Controlled Trials, MEDLINE (January 1966 to October 3 2003), EMBASE (January 1980 to October 3 2003) and the European Neuromuscular Centre (ENMC) clinical trials register, and contacted experts in the field.


METHODS
We included randomised controlled trials (including crossover studies) and quasi-randomised trials comparing pharmacological treatments, and non-pharmacological treatments (vitamins and food supplements), and physical training in individuals with mitochondrial disorders. The primary outcome measures included an improvement in muscle strength and/or endurance, or neurological clinical features. Secondary outcome measures included quality of life assessments, biochemical markers of disease and negative outcomes.


METHODS
Details of the number of randomised patients, treatment, study design, study category, allocation concealment and patient characteristics were extracted. Analysis was based on intention to treat data. We planned to use meta-analysis, but this did not prove necessary.


RESULTS
Six hundred and seventy-eight abstracts were reviewed, and six fulfilled the entry criteria. Two trials studied the effects of co-enzyme Q10 (ubiquinone), one reporting a subjective improvement and a significant increase in a global scale of muscle strength, but the other trial did not show any benefit. Two trials used creatine, with one reporting improved measures of muscle strength and post-exercise lactate, but the other reported no benefit. One trial of dichloroacetate showed an improvement in secondary outcome measures of mitochondrial metabolism, and one trial using dimethylglycine showed no significant effect.


CONCLUSIONS
There is currently no clear evidence supporting the use of any intervention in mitochondrial disorders. Further research is needed to establish the role of a wide range of therapeutic approaches.
Chinnery
P
P
University of Newcastle upon Tyne, Department of Neurology, Medical School, Framlington Place, Newcastle Upon Tyne, UK, NE24 4HH. p.f.chinnery@ncl.ac.uk
Majamaa
K
K
Turnbull
D
D
Thorburn
D
D
D003401:Creatine / Q000627:therapeutic use; D003999:Dichloroacetic Acid / Q000627:therapeutic use; D006801:Humans; D028361:Mitochondrial Diseases / Q000188:drug therapy*; D012521:Sarcosine / Q000031:analogs & derivatives / Q000627:therapeutic use; D014451:Ubiquinone / Q000627:therapeutic use
D014451:Ubiquinone; C025138:dimethylglycine; D003999:Dichloroacetic Acid; D003401:Creatine; D012521:Sarcosine