Magnetic resonance imaging correlates of genetically characterized patients with mitochondrial disorders: A study from south India.
BACKGROUND
Large studies analyzing magnetic resonance imaging correlates in different genotypes of mitochondrial disorders are far and few. This study sought to analyze the pattern of magnetic resonance imaging findings in a cohort of genetically characterized patients with mitochondrial disorders.


METHODS
The study cohort included 33 patients (age range 18 months-50 years, M:F - 0.9:1) with definite mitochondrial disorders seen over a period of 8 yrs. (2006-2013). Their MR imaging findings were analyzed retrospectively.


RESULTS
The patients were classified into three groups according to the genotype, Mitochondrial point mutations and deletions (n=21), SURF1 mutations (n=7) and POLG1 (n=5). The major findings included cerebellar atrophy (51.4%), cerebral atrophy (24.2%), signal changes in basal ganglia (45.7%), brainstem (34.2%) & white matter (18.1%) and stroke like lesions (25.7%). Spinal cord imaging showed signal changes in 4/6 patients. Analysis of the special sequences revealed, basal ganglia mineralization (7/22), lactate peak on magnetic resonance spectrometry (10/15), and diffusion restriction (6/22). Follow-up images in six patients showed that the findings are dynamic. Comparison of the magnetic resonance imaging findings in the three groups showed that cerebral atrophy and cerebellar atrophy, cortical signal changes and basal ganglia mineralization were seen mostly in patients with mitochondrial mutation. Brainstem signal changes with or without striatal lesions were characteristically noted in SURF1 group. There was no consistent imaging pattern in POLG1 group.


CONCLUSIONS
Magnetic resonance imaging findings in mitochondrial disorders are heterogeneous. Definite differences were noted in the frequency of anatomical involvement in the three groups. Familiarity with the imaging findings in different genotypes of mitochondrial disorders along with careful analysis of the family history, clinical presentation, biochemical findings, histochemical and structural analysis will help the physician for targeted metabolic and genetic testing.
Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.
Parayil Sankaran
PS
Bindu
Department of Neuroimaging and Interventional Radiology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.
Hanumanthapura
H
Arvinda
Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India. Electronic address: abtaly@yahoo.com.
Arun B
AB
Taly
Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.
Chikanna
C
Govindaraju
Department of Clinical Neurosciences, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.
Kothari
K
Sonam
Department of Clinical Neurosciences, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.
Shwetha
S
Chiplunkar
Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.
Rakesh
R
Kumar
Department of Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.
Narayanappa
N
Gayathri
Department of Neurochemistry, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.
Srinivas
S
Bharath Mm
Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.
Madhu
M
Nagappa
Department of Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, India.
Sanjib
S
Sinha
Centre for Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR-CCMB), Hyderabad, India.
Nahid Akthar
NA
Khan
Centre for Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR-CCMB), Hyderabad, India.
Periyasamy
P
Govindaraj
Centre for Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR-CCMB), Hyderabad, India.
Vandana
V
Nunia
Centre for Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR-CCMB), Hyderabad, India.
Arumugam
A
Paramasivam
Centre for Scientific and Industrial Research-Centre for Cellular and Molecular Biology (CSIR-CCMB), Hyderabad, India.
Kumarasamy
K
Thangaraj
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D000074002:DNA Polymerase gamma; D004259:DNA-Directed DNA Polymerase / Q000235:genetics; D006801:Humans; D007194:India; D007223:Infant; D008279:Magnetic Resonance Imaging; D008297:Male; D008565:Membrane Proteins / Q000235:genetics; D008875:Middle Aged; D028361:Mitochondrial Diseases / Q000473:pathology*; D024101:Mitochondrial Proteins / Q000235:genetics; D017354:Point Mutation; D012189:Retrospective Studies; D017384:Sequence Deletion; D055815:Young Adult
D008565:Membrane Proteins; D024101:Mitochondrial Proteins; C092928:Surf-1 protein; D000074002:DNA Polymerase gamma; D004259:DNA-Directed DNA Polymerase; C413027:POLG protein, human
MELAS; MRI; Mitochondrial disorders; POLG1; SURF1; Stroke like lesions; m.3243A>G