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Neurology India
Medknow Publications on behalf of the Neurological Society of India
ISSN: 0028-3886
EISSN: 0028-3886
Vol. 52, No. 3, 2004, pp. 353-358
Bioline Code: ni04115
Full paper language: English
Document type: Research Article
Document available free of charge

Neurology India, Vol. 52, No. 3, 2004, pp. 353-358

 en Diagnosis of mitochondrial diseases: Clinical and histological study of sixty patients with ragged red fibers
Challa Sundaram, Kanikannan MeenaA, Jagarlapudi MurthyMK, Bhoompally VenkateswarR, Surath Mohandas


Background: Mitochondrial diseases are caused by mutations in mitochondrial or nuclear genes, or both and most patients do not present with easily recognizable disorders. The characteristic morphologic change in muscle biopsy, ragged-red fibers (RRFs) provides an important clue to the diagnosis.
Materials and Methods: Demographic data, presenting symptoms, neurological features, and investigative findings in 60 patients with ragged-red fibers (RRFs) on muscle biopsy, seen between January 1990 and December 2002, were analyzed. The authors applied the modified respiratory chain (RC) diagnostic criteria retrospectively to determine the number of cases fulfilling the diagnostic criteria of mitochondrial disease.
Results: The most common clinical syndrome associated with RRFs on muscle biopsy was progressive external ophthalmoplegia (PEO) with or without other signs, in 38 (63%) patients. Twenty-six patients (43%) had only external ophthalmoplegia, 5 (8%) patients presented with encephalomyopathy. Specific syndromes were the presenting feature in 8 (13%), Kearns-Sayre syndrome (KSS) in 4 and myoclonus epilepsy with ragged-red fibers (MERRF) in 4. Myopathy was the presenting feature in 5 (8%) and 4 presented with infantile myopathy. Of the 60 patients, 18 (30%) had proximal muscle weakness. Two patients with KSS and one patient with myopathy had complete heart block necessitating pace making. When the modified RC diagnostic criteria were applied, only 26 (43%) patients had one other major criterion in addition to RRFs for the diagnosis of mitochondrial diseases. The remaining 34 (57%) patients with RRFs on muscle biopsy had only some clinical features suggestive of RC disorder but did not fulfill the clinical criteria (of the modified diagnostic criteria) for the diagnosis of mitochondrial diseases.
Conclusion: In patients with clinical features suggestive of RC disorder, demonstration of RRFs on muscle biopsy helps in confirming the diagnosis of mitochondrial disease in only a subgroup of patients.

Mitochondrial disease, Ragged-red fiber, Progressive external ophthalmoplegia, Kearns-Sayre syndrome, Myoclonus epilepsy with ragged-red fibers, Heart block.

© Copyright 2004 Neurology India.
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