To the Editor
With read with interest the article by Bell et al1 about the intrahospital course and anesthetic management of a 36-year-old gravida-2 para-0 woman with genetically nonconfirmed mitochondrial encephalopathy with lactic acidosis and stroke-like episodes (MELAS) syndrome, who experienced severe pre-eclampsia, complicated by hyponatremia, hyperkalemia, and diabetes. We have the following comments and concerns.
Although the patient presented with features suggestive of a mitochondrial disorder, the described phenotype was not genetically confirmed. The patient manifested phenotypically with short stature, hypoacusis, stroke-like episodes (SLEs), cerebral atrophy, hyperuricemia, and arterial hypertension. Because MELAS syndrome was diagnosed also in the mother and sister of the index case, we should be informed if the diagnosis was based on genetic studies in these 2 first-degree relatives. Did muscle biopsy in the index case show typical features, such as ragged fibers, COX-negative fibers, SDH-hyperreactive fibers, deposition of lipid or glycogen droplets, and abnormally shaped and structured mitochondria?
MELAS frequently manifests with epilepsy.2 Was an electroencephalogram recorded during the acute episode with headache, expressive dysphasia, right hemiparesis, and lip tingling? Was cerebral magnetic resonance imaging during this episode unchanged to previous investigations or indicative of a stroke-like lesion, the morphological equivalent of a SLE? Did the patient ever require antiepileptic drug treatment?
The patient is reported to have had developed exertional dyspnea. What was the cause? Heart failure, pulmonary compromise, pulmonary hypertension, arrhythmias, respiratory muscle involvement, acidosis, or infection? Did the patient undergo appropriate investigations to clarify the cause?
The index case is reported to have been pregnant previously without delivering the child. Was the first pregnancy terminated or a spontaneous abortion? Was the first fetus/embryo investigated for features of MELAS or MELAS mutations?
The authors conclude that neuraxial anesthesia is safe in patients with a mitochondrial disorder.1 However, there are a number of reports showing that volatile anesthetics and some local anesthetics may induce severe side effects in these patients.3
The cerebral computed tomography scan shown in Figure 2 of the case report does not show any remnants of the previous SLE at age 23 years. What were the clinical manifestations of this SLE? What were the morphological findings on magnetic resonance imaging? Did the patient present with typical vasogenic edema not confined to a vascular territory in the acute stage? Did the morphological lesion completely resolve?
It is reported that eclampsia may be due to mitochondrial dysfunction.1 Following this assumption, one might expect an increased frequency of eclampsia in women with a mitochondrial disorder, which is obviously not the case. However, a systematic study on this issue has not been performed. A literature search revealed that eclampsia/pre-eclampsia may not only occur in MELAS but also in other specific or nonspecific mitochondrial disorders (Table).
Overall, this interesting case could be more meaningful if the diagnosis would be confirmed by genetic investigations. Because the disease was obviously maternally inherited, we can expect a mtDNA mutation, which can be easily confirmed by mtDNA sequencing. There is also a need to investigate the index case for involvement of organs other than the reported ones. Furthermore, if available, material from the 2 embryos should be investigated for mitochondrial disorder.
Josef Finsterer, MD, PhD
Sinda Zarrouk-Mahjoub, PhD
University of Tunis El Manar and Genomics Platform
Pasteur Institute of Tunis
1. Bell JD, Higgie K, Joshi M, Rucker J, Farzi S, Siddiqui NAnesthetic management of mitochondrial encephalopathy with lactic acidosis and stroke-like episodes (MELAS Syndrome) in a high-risk pregnancy: a case report. A A Case Rep. 2017. doi: 10.1213/XAA.0000000000000520.
2. Finsterer J, Zarrouk Mahjoub SMitochondrial epilepsy in pediatric and adult patients. Acta Neurol Scand. 2013;128:141–152.
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