Discussion and Conclusion
Mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like
episodes (MELAS) is the most common maternally-inherited mitochondrial
disorder, which usually becomes symptomatic before the age of 40
years8. MELAS is characterized by stroke-like
episodes, seizures, dementia, encephalopathy, lactic acidosis and also
RRFs on muscle biopsy9.
Previous studies reporting cases of MELAS have shown specific
characteristics on brain MRI imaging of these patients. Transient
stroke-like lesions have been reported in these patients, typically
affecting gray matter without being restricted to vascular areas.
Involvement of white matter has also been observed in MELAS, being more
distinguished in periventricular white matter and centrum semiovale. All
the previously reported cases of MELAS have reported a fluctuating
characteristic for the lesions observed in the brain
MRI10.
The case we report here suffered from progressive cognitive decline,
encephalopathy, seizures and stroke-like episodes, being compatible with
the previously reported cases of MELAS. Nevertheless, this patient had
some unique features, never reported in cases of MELAS so far, leading
to mismanagement. Since structural heart diseases are more common in
young adults with stroke11; to rule out the presence
of any heart diseases, echocardiography was performed in our patient and
patent foramen ovale (PFO) was discovered and confirmed with
trans-esophageal echocardiography (TEE). This finding was first
misdiagnosed as the reason for the patient’s symptoms, medication was
prescribed according to this finding and further investigations were
postponed to his next admissions. Despite treatment with anticoagulant,
the patient had had another stroke, so investigation was done again to
find a cause and led to diagnosis of MELAS.
Our literature review revealed no evidence of existing PFO in MELAS
cases. Johnson et al. described a MELAS patient in their case report who
was once diagnosed with PFO in echocardiography which was later ruled
out with TEE. The only reason they could find for the incidence of
stroke in their patient was MELAS syndrome13.
Another unique presentation in our patient was the pattern of ischemia
lesions being different from the previously reported fluctuating
characteristic of the lesions on MRI, lesions had a progressive pattern
in this patient and every time he was admitted, new lesions were added
to the old ones, without disappearing of previous lesions.
In conclusion, this is the first reported case of MELAS syndrome with
PFO and progressive pattern of ischemic lesions on brain MR imaging. The
presence of PFO has led to mismanagement and late diagnosis in this
patient. For this reason further investigations are recommended to rule
out PFO in MELAS cases presenting by stroke-like symptoms.
All procedures performed in this study were in accordance with the
ethical standards of Shahid Beheshti Medical University research ethics
committee and with the 1964 Helsinki Declarations and its later
amendments. The study was approved by the Bioethics Committee of the
Medical University of the Medical University of Shahid Beheshti.