Leigh syndrome, a mitochondrial encephalo(myo)pathy. A review of the literature

Infant onset subacute necrotizing encephalomyelopathy (Leigh's disease)

We reviewed six cases of proven or probable subacute necrotizing encephalomyelopathy with an onset under 12 months of age. All children had been investigated at the Adelaide Children's Hospital in the period 1975-90. Seizures (five of six) and cortical blindness (five of six) were more prominent clinical features at presentation than the literature would suggest, while respiratory abnormalities and developmental delay were also frequent. Flash visual evoked responses, brain-stem auditory evoked responses, and the interictal electroencephalogram did not contributed to diagnosis. Computerized tomography brain scans were abnormal in three of four cases with typical basal ganglia lesions in one case and brain atrophy in two cases. The diagnosis was suspected in four cases with raised blood or cerebrospinal fluid lactate concentrations. The importance of obtaining a blood or cerebrospinal fluid lactate in all infants with unexplained seizures, cortical blindness or apnoea is emphasized.

Proton spectroscopy in five patients with Leigh's disease and mitochondrial enzyme deficiency

Five children with Leigh's disease and progressive neurological symptoms were compared with 14 control children. In all patients, MRI showed bilateral lesions of the putamina and caudate heads. Serum lactate was normal for four of the children, and CSF lactate slightly elevated for three. Volume-selective proton MR spectroscopy (1H-MRS) of the basal ganglia in the Leigh patients revealed elevated lactate, giving further evidence for a defect of energy metabolism in the brain. 1H-MRS is an important tool for non-invasive brain tissue analysis in Leigh's disease, particularly in the absence of peripheral lactate elevation.

A second missense mutation in the mitochondrial ATPase 6 gene in Leigh's syndrome

By direct sequencing, we have discovered a novel heteroplasmic mutation (T-->C) at nucleotide position 8993 in the mitochondrial ATPase 6 gene in a family with Leigh's syndrome. Another mutation in the same codon (T8993G) has been reported before in Leigh's syndrome. As these two mutations led to different amino acid substitutions, it provides strong evidence for the relevance of ATP synthase dysfunction in maternally inherited Leigh's syndrome.

Molecular genetic characterization of an X-linked form of Leigh's syndrome

We report a patient with necrotizing encephalomyelopathy (Leigh's syndrome) associated with a deficiency of pyruvate dehydrogenase complex activity. The underlying mutation is an A to C transversion in the pyruvate dehydrogenase complex E1 alpha subunit gene. As the E1 alpha subunit is encoded on the X chromosome, this observation confirms that some patients with Leigh's syndrome may potentially exhibit X-linked inheritance.

Aplasia of the retinal vessels combined with optic nerve hypoplasia, neonatal epileptic seizures, and lactic acidosis due to mitochondrial complex I deficiency

A newborn male with mitochondrial complex I deficiency suffered from neonatal epileptic seizures, which later developed into infantile spasms. The infant was blind due to aplasia of the retinal vessels and hypoplasia of the optic nerve. There was congenital lactic acidosis, which persisted in later life. The boy was microcephalic and retarded. Muscular hypotonia later shifted to spasticity. Succinic acid was increased in urine. We assume that the aplasia of the retinal vessels is due to damage of the retinal ganglion cells caused by the mitochondrial disease in the first 3 to 4 months of pregnancy.

Assessment and therapy monitoring of Leigh disease by MRI and proton spectroscopy

In a 2-year-old boy with Leigh disease, spasticity, dysarthria, and optic atrophy gradually developed. Computed tomography and magnetic resonance imaging disclosed progressive, symmetric basal ganglia lesions. In muscle tissue, a defect of pyruvate dehydrogenase complex was found. Magnetic resonance volume selective proton spectroscopy (MRVS) of the basal ganglia demonstrated an abnormal lactate peak. A ketonemic diet coincided with clinical stabilization and arrest of progressive brain lesions. Lactate could no longer be demonstrated by MRVS. It reappeared with a new brain lesion coinciding with discontinuation of the diet. MRVS, therefore, appears to be a sensitive tool to evaluate pathologic lactate production in metabolic brain disease with disturbed energy metabolism and allows noninvasive therapy monitoring.

Bilateral striatal necrosis, dystonia and optic atrophy in two siblings

Two siblings developed a neurological disorder in the first decade characterised by generalised dystonia, hypokinesia, and subacute visual loss. CT and serial MRI examinations showed bilateral lesions of the striatum, mainly in the putamen. The classification of these patients is discussed in relation to infantile bilateral striatal necrosis (IBSN), Leigh's disease, and Leber's optic neuropathy. The literature shows a clinical and aetiopathogenetic overlap between these syndromes. In our cases parental consanguinity and the involvement of a single generation suggest a new clinical condition with autosomal recessive transmission.

Stroke in pediatric acquired immunodeficiency syndrome

In a 4 1/2-year period, 4 of 68 children in a longitudinal study of neurological complications of human immunodeficiency virus (HIV) infection had clinical and/or neuroradiological evidence of stroke, yielding a clinical incidence of stroke in this population of 1.3% per year. During this period, 32 subjects died, and permission for autopsy was granted in 18 of the patients, including 3 of 4 who had clinical evidence of stroke. The prevalence of cerebrovascular pathological features in our consecutive autopsy series was higher than the clinical incidence. At autopsy cerebrovascular disease was documented in 6 (24%) of 25 children with HIV infection, including all 3 children who had clinical evidence of stroke. Four patients had intracerebral hemorrhages, 6 patients had nonhemorrhagic infarcts, and 3 had both. Hemorrhage was catastrophic in 1 child and clinically silent in 3 children, all of whom had immune thrombocytopenia. One child had an arteriopathy that affected meningocerebral arteries. In another child, the arteries of the circle of Willis were aneurysmally dilated. Two children had coexisting cardiomyopathy and subacute necrotizing encephalomyelopathy with vascular proliferation. These results suggest that stroke should be considered when children with HIV infection develop focal neurological signs.

Neuropathologic findings after bone marrow transplantation: an autopsy study

Clinicopathologic records and neuropathologic tissues of 109 patients who underwent necropsy after treatment with bone marrow transplantation (BMT) were examined. Underlying disorders included leukemia (70), aplastic anemia (25), solid tumors (7), lymphoma (5), Hodgkin's disease (1) and Wiskott-Aldrich syndrome (1). There were 34 females and 75 males, ranging in age from 2 to 56 years. Survival after transplantation averaged 3.6 months. The most common findings were cerebrovascular lesions (29), including hematomas, hemorrhagic necrosis, and infarcts. Central nervous system infections comprised the next most common finding, including 10 fungal and four bacterial infections. A recurrence of underlying malignancy for which transplant had been performed occurred in five patients. Leukoencephalopathy of varying severity was found in eight patients, half of whom had received intrathecal chemotherapy and/or cranial radiation. Patients with systemic graft-versus-host disease had a variety of nonspecific neuropathologic findings in the nervous system; however, nearly half (44%) showed no detectable changes. Other nonspecific alterations included hypoxic/ischemic changes, vascular siderocalcinosis, and neuroaxonal spheroids (associated with hemorrhage or necrosis). These findings provide a guide as to likely causes of a neurologic syndrome in a patient who has undergone BMT, and can be compared with neuropathologic findings in other forms of immunosuppression.

Acute respiratory failure precipitated by general anesthesia in Leigh's syndrome

Three patients with Leigh's syndrome developed respiratory failure following general anesthesia. Although all three had respiratory symptoms prior to the anesthetic, the diagnosis was not suspected at the time of the procedure in two of the children. We reviewed the case notes of 16 other patients with Leigh's syndrome. Eight had received anesthetic agents without incident. Although the majority subsequently developed respiratory abnormalities and died with respiratory failure, this problem was not evident at the time of anesthesia. In the presence of respiratory abnormalities, general anesthesia carries significant risks in Leigh's syndrome.

Subacute necrotizing encephalomyelopathy (Leigh disease): CT and MRI appearances

Subacute necrotizing encephalomyelopathy (SNE) is a genetic disorder of pyruvate metabolism. Until recently the diagnosis of SNE could only be made at autopsy. However, an antemortem diagnosis can now be suggested by the correlation of clinical and laboratory data with computed tomography (CT) and/or magnetic resonance imaging (MRI). Five children with clinical and laboratory data suggesting the diagnosis of Leigh disease were evaluated by CT and MR. MR was found to be more sensitive than CT in the detection of areas of necrosis in the brain of the five children we studied. The absence of focal lesions detected by either modality in one of our patients did not exclude the diagnosis of SNE since focal lesions were present at autopsy one month following CT and MR.

Acute metabolic encephalopathy: a review of causes, mechanisms and treatment

Acute encephalopathy is a relatively common problem: one of the causes is metabolic disorders. A detailed history, examination and investigations performed during the acute illness (blood sugar, blood gases, plasma ammonia, blood lactate, plasma ketones, plasma amino acids, liver function tests, and urinary organic acids) should identify those patients in whom a metabolic disorder is likely. More detailed studies may be needed to establish a precise diagnosis. The mechanism of the acute brain dysfunction is multifactorial. Factors that contribute include changes in blood flow and, initially, a disturbance in neurotransmitter function followed by failure of energy metabolism and cellular depolarization. Treatment of these conditions is largely supportive, with special attention to the management of cerebral perfusion pressure.