The New England Journal of MedicineCase 12-2024: A 58-Year-Old Woman with Confusion, Aphasia, and Abnormal Head Imaging

Unraveling a Complex Case: Exploring the Intersection of Mitochondrial Disorders and Neurological Manifestations

A complex medical case unfolds as a 58-year-old woman presents with confusion, aphasia, and abnormal head imaging, leading physicians through a diagnostic odyssey encompassing autoimmune encephalitis, infectious etiologies, cancer, strokes, demyelinating disorders, toxic exposures, and genetic considerations, ultimately revealing a rare mitochondrial disorder.

Key Points:

• Presentation and Medical History:
  • The patient initially presented with confusion and expressive and auditory aphasia, with MRI showing signal hyperintensities in the left temporal lobe and elevated CSF glucose and protein.
  • Despite treatment with glucocorticoids and surgical removal of a teratoma, confusion persisted, prompting further investigation.
• Differential Diagnosis:
  • Considerations included autoimmune encephalitis, infections, cancer, multifocal strokes, demyelinating and inflammatory disorders, toxic exposures, metabolic disorders, and genetic disorders.
  • Findings such as generalized EEG slowing, persistent auditory aphasia, and multifocal MRI lesions challenged the initial autoimmune encephalitis diagnosis.
• Genetic Testing and Diagnosis:
  • Mitochondrial disorder was suspected due to family history, sensorineural hearing loss, diabetes, and elevated blood lactate levels.
  • Muscle biopsy revealed ragged-red fibers and COX-deficient fibers, confirming mitochondrial cytopathy, with genetic testing identifying the m.3243A→G pathogenic variant.
• Management and Prognosis:
  • Treatment included mitochondrial supplements, oral arginine for stroke prevention, and rehabilitation, but the patient experienced ongoing cognitive decline and metabolic issues.
  • Despite initial stabilization, the patient’s condition deteriorated, leading to hospitalization and transition to hospice care.

Mitochondrial disease is one of the most common groups of genetic diseases with a minimum prevalence of greater than 1 in 5,000 in adults.

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