Subacute necrotizing encephalopathy

Subacute Necrotizing Encephalopathy

Subacute Necrotizing Encephalopathy (SNE), also known as Leigh Syndrome, is a rare, progressive neurodegenerative disorder that primarily affects the central nervous system. It is characterized by the degeneration of the brain, particularly the basal ganglia, thalamus, brainstem, and spinal cord.

Etiology

SNE is most commonly caused by genetic mutations that affect mitochondrial function. These mutations can be inherited in an autosomal recessive, X-linked, or mitochondrial pattern. The most common genetic cause is a mutation in the MT-ATP6 gene, which is involved in the production of ATP, the energy currency of the cell.

Pathophysiology

The pathophysiology of SNE involves defects in mitochondrial energy production, leading to a lack of ATP and an accumulation of lactic acid. This results in the death of neurons and the characteristic lesions seen in the brain. The mitochondrial respiratory chain is often impaired, particularly complexes I and IV.

Clinical Features

Symptoms of SNE typically begin in infancy or early childhood, although adult-onset cases have been reported. Common symptoms include:

• Developmental delay
• Hypotonia (reduced muscle tone)
• Ataxia (lack of voluntary coordination of muscle movements)
• Seizures
• Respiratory problems
• Ophthalmoplegia (paralysis or weakness of the eye muscles)

Diagnosis

Diagnosis of SNE is based on clinical presentation, neuroimaging, and genetic testing. MRI of the brain often shows symmetrical lesions in the basal ganglia and brainstem. Genetic testing can confirm mutations in genes associated with the disease.

Treatment

There is currently no cure for SNE. Treatment is supportive and focuses on managing symptoms and complications. This may include:

• Nutritional support
• Physical therapy
• Anticonvulsants for seizures
• Respiratory support

Prognosis

The prognosis for individuals with SNE is generally poor, with many affected individuals not surviving beyond early childhood. However, the course of the disease can vary depending on the specific genetic mutation and other factors.

Research

Ongoing research is focused on understanding the genetic and biochemical basis of SNE, as well as developing potential therapies. Gene therapy and mitochondrial replacement therapy are areas of active investigation.

See Also

• Mitochondrial diseases
• Leigh Syndrome
• Neurological disorders

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NIH genetic and rare disease info

• NIH info on Subacute necrotizing encephalopathy

Subacute necrotizing encephalopathy is a rare disease.