Affiliations: Department of Neonatology, The Royal Children's
Hospital, Melbourne, Victoria, Australia | Johns Hopkins University School of Medicine,
Baltimore, MD, USA | Department of Radiology, The Royal Children's
Hospital, Melbourne, Victoria, Australia
Note: [] Correspondence: Dr. Rod W. Hunt, PhD, The Royal Children's
Hospital, Department of Neonatal Medicine, Flemington Road, Parkville 3052,
VIC, Australia. Tel.: +61 3 9345 5008; Fax: +61 3 9345 5067; E-mail:
rod.hunt@rch.org.au
Abstract: Amplitude-integrated electroencephalography (aEEG) findings in
hypoxic-ischemic encephalopathy characterized by secondary energy failure have
been described in detail. In contrast, reports of use of aEEG in patients with
encephalopathy due to primary energy failure as seen in inherited metabolic
disorders are sparse. We report two cases of lethal mitochondrial
encephalopathy due to mitochondrial respiratory chain complex I deficiency. We
present clinical course, laboratory evaluations, aEEG, conventional
electroencephalography, magnetic resonance imaging and magnetic resonance
spectroscopy findings of two cases identified with mitochondrial encephalopathy
between 2002 and 2007. Both infants were born at term. Both presented with
intractable seizures and mild hypotonia within the first days of life, in the
absence of any evidence suggestive of hypoxic-ischemic encephalopathy. Both
cases were treated with multiple anticonvulsants and in neither case were
seizures fully controlled. Magnetic resonance imaging in both cases revealed a
structurally normal brain and case one showed subtle diffuse deep white matter
signal abnormality. Magnetic resonance spectroscopy revealed no elevation of
lactate. In both cases, aEEG tracings were markedly abnormal, confirmed by
electroencephalography. Case one showed status epilepticus on an abnormally
high amplitude background and case two presented with a mainly discontinuous
background pattern with intermittent burst-suppression pattern activity.
Complex I activity in skeletal muscle homogenate was abnormally low in both
patients. The use of aEEG as a valuable assessment and monitoring tool in
patients with metabolic encephalopathy should be further promoted.
