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Neurology India
Medknow Publications on behalf of the Neurological Society of India
ISSN: 0028-3886 EISSN: 1998-4022
Vol. 52, Num. 4, 2004, pp. 511-512

Neurology India, Vol. 52, No. 4, October-December, 2004, pp. 511-512

Letter To Editor

Diagnostic approach for adult mitochondriopathy with limited resources

Department of Neurology, Krankenanstalt Rudolfstiftung, Univ.Doz. DDr. J. Finsterer, Postfach 20, 1180 Wien, Austria
Correspondence Address:Department of Neurology, Krankenanstalt Rudolfstiftung, Univ.Doz. DDr. J. Finsterer, Postfach 20, 1180 Wien, Austria,

Code Number: ni04173


We appreciated reading the paper by Challa et al.[1] on the findings in 60 adult patients with respiratory-chain-disorder (RCD), diagnosed during 12y according to Bernier′s criteria.[2] The study raises the following concerns:

What was the indication for muscle-biopsy in those patients without evidence for myopathy? Only 18/60 patients presented with proximal weakness, only 5/35 had elevated CK, and only 12/31 myopathic EMG.

Why was the left vastus lateralis muscle chosen in all cases? It appears unlikely that this muscle was affected in all 60 patients, given the facts that 26 had only chronic external ophthalmoplegia (CPEO), that only 3 of those with CPEO and other signs had myopathy, and that only 30% had proximal weakness. Thus, RRFs >2% in 25/60 investigated muscles suggests subclinical involvement of certain limb muscles in MCP.

Why did only 8% of the patients present with additional non-neurological manifestations? Multisystem involvement is a dominant feature in the majority of MCP patients.[3] Could the low number of patients with cardiac involvement result from the small number of patients undergoing comprehensive cardiologic examination? Only 35 had an ECG and only 13 underwent echocardiography. Which specific abnormalities were found in the 13 who underwent echocardiography? Did the investigators also look for left-ventricular hypertrabeculation?

Also noteworthy are the low prevalence of diabetes, hyper-CK-aemia, and polyneuropathy. In a retrospective study on 130 MCP-patients, the prevalence of diabetes was 12%,[3] that of hyper-CK-aemia 42%, and that of polyneuropathy 35%.[3]

Latency between onset and diagnosis was relatively short. The number of 6.7y remains questionable given the fact that mean age at onset was 19.7y and mean age at diagnosis 29.3y.

We don′t agree with the statement that MCP is mostly associated with various central-nervous-system (CNS) symptoms. Although subclinical abnormalities, like cortical or cerebellar atrophy, homogenous parieto-temporal hyperintesities, non-specific white matter lesions, or uni- or bilateral basal ganglia calcifications are often found in adult MCP patients, overt CNS-affection, including dementia, migraine, stroke, Parkinson syndrome, spasticity, ataxia, or dystonia, is rather rare among adults. The authors themselves report only 5/60 patients presenting with encephalomyopathy.

Overall, there is subclinical muscle-affection in MCP long before any clinical manifestation; MCP can be diagnosed even without sophisticated and cost-expensive methods; there is multi-organ involvement in MCP; onset of MCP is quite variable, and patients with suspected MCP should be thoroughly investigated for clinical and subclinical affection of the CNS, PNS, endocrinologic system, heart, eyes, ears, guts, dermis, and bone-marrow.


1.Challa S, Kanikannan MA, Murthy JMK, Bhoompally VR, Surath M. Diagnosis of mitochondrial disease: Clinical and Histologic study of sixty patients with ragged red fibers. Neurol India 2004;52:353-8.  Back to cited text no. 1    
2.Bernier FP, Boneh A, Dennett X, Chow CW, Cleary MA, Thorburn DR. Diagnsotic criteria for respiratory chain disorders in adults and children. Neurology 2002;59:1406-11.  Back to cited text no. 2  [PUBMED]  [FULLTEXT]
3.Finsterer J, Jarius C, Eichberger H, Jaksch M. Phenotype variability in 130 adult patients with respiratory chain disorder. J Inher Metab Dis 2001;24:560-76.  Back to cited text no. 3    
4. Finsterer J, Stöllberger C, Blazek G, Spahits E. Cardiac involvement in myotonic dystrophy, Becker muscular dystrophy and mitochondrial myopathy: A five year follow-up. Can J Cardiol 2001;17:1061-9.

Copyright 2004 - Neurology India

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