Josef Finsterer

Josef Finsterer,Neurological Department,Messerli Institute,Vienna 1180,Austria

Abstract

Key words: Heteroplasmy;mtDNA;Oxidative phosphorylation;Stroke-like episode

TO THE EDITOR

In a recent article,Fuet al[1]reported about a 52 years female with a mitochondrial disorder (MID) due to the variant m.10158T＞C inMT-ND3.The patient manifested phenotypically with recurrent stroke-like episodes,cluster headache,and epilepsy.We have the following comments and concerns.

We do not agree with the statement that the m.10158T＞C variant inND3is a common mutation[1].When searching PubMed for this particular mtDNA variant only five hits could be achieved.Thus,the variant m.101157T＞C has to be classified as a rare variant.

Since the index patient had undergone a spinal tap,we should know if cerebrospinal fluid (CSF) lactate was elevated or not upon investigations of the CSF.

Since up to 75% of the mtDNA variants are transmittedviaa maternal line of inheritance[2],we should know if the mother or any other first degree elative was clinically affected and if the mtDNA variant m.10158T＞C was detected in any of the other first degree relatives.

Stroke-like lesions (SLLs) in the acute/expanding stage typically manifest with hyperperfusion on single-photon emission computed tomography or perfusion weighted imaging.Thus,we should know if perfusion weighted imaging was applied and if hyperperfusion could be detected.It is also crucial to demonstrate reduced oxygen extraction within the SLL by means of oxygen extraction fraction-MRI.Was this technique applied and was there reduced oxygen extraction?

Since SLLs may disappear without any remnants on MRI,or may end up as white matter lesion,laminar cortical necrosis,cysts,or the toenail-sign[3],we should know the outcome of the various SLLs in this patient.Which were the results of the longterm follow-up on MRI?

The index patient obviously did not only manifest in the cerebrum (SLLs,seizures,cognitive impairment) but also in the endocrine system (short stature),and the heart(atrial fibrillation).Since patients with a MID most frequently manifest with multisystem disease[4],we should know if the index patient was prospectively investigated for manifestations of the genotype in organs other than the brain and the endocrine organs.We also should be informed why the patient received oral anticoagulation with a vitamin-K antagonist.Was this due to atrial fibrillation,heart failure,or valve replacement therapy?

Missing is the current medication of the patient.Since the patient had experienced recurrent seizures,it is crucial to know the antiepileptic drug (AED) regimen.Since some of the AEDs are potentially mitochondrion-toxic[5]we should know if recurrence of seizures and SLLs could be attributed at least in part to the application of mitochondrion-toxic AEDs or to in-effectivity of the AEDs.

Cluster headache had been occasionally reported as a manifestation of a MID[6,7].Did cluster headache in the index patient resolve upon application of widely agreed therapies for cluster headache?

Overall,this interesting case could be more meaningful by providing more data about multisystem disease,the current medication,the CSF findings,the phenotype and genotype of other first-degree relatives,outcome of the SLLs on imaging,and by discussing more profoundly the imaging findings and their significance.