Differential Diagnosis for Generalized Tonic Posturing in a 3-Month-Old Since 6 Days of Life

Single Most Likely Diagnosis

• Benign Neonatal Sleep Myoclonus: This condition is characterized by sudden, brief contractions of muscle groups that can occur in newborns, often mistaken for seizures. Given the age and presentation, this could be a plausible explanation, especially if the episodes are brief and occur during sleep.

Other Likely Diagnoses

• Infantile Spasms: A form of epilepsy that typically begins within the first year of life, often between 4-8 months, but can start as early as a few weeks of age. The spasms can manifest as tonic posturing.
• Hypoxic-Ischemic Encephalopathy: If the infant experienced a period of hypoxia or ischemia, this could lead to neurological manifestations including seizures or abnormal posturing.
• Metabolic Disorders: Certain metabolic disorders can present with neurological symptoms, including seizures or abnormal movements, due to accumulation of toxic substances or deficiency of crucial metabolites.

Do Not Miss Diagnoses

• Infections (Meningitis, Encephalitis): Infections of the central nervous system can present with seizures, altered mental status, and abnormal posturing. Early diagnosis and treatment are crucial to prevent long-term sequelae or death.
• Intracranial Hemorrhage: Bleeding within the brain can cause increased intracranial pressure, leading to symptoms such as seizures, vomiting, and changes in consciousness or muscle tone.
• Congenital Infections: Infections acquired in utero, such as toxoplasmosis, rubella, cytomegalovirus, and herpes simplex virus, can cause a range of neurological symptoms, including seizures.

Rare Diagnoses

• Aicardi Syndrome: A rare genetic disorder that affects the development of the brain and is characterized by infantile spasms, among other features.
• Tuberous Sclerosis Complex: A genetic disorder that can cause seizures, developmental delay, and characteristic skin and brain lesions.
• Pyridoxine-Dependent Epilepsy: A rare condition where seizures are resistant to conventional antiepileptic drugs but respond to pyridoxine (vitamin B6) supplementation.

Each of these diagnoses requires careful consideration of the clinical presentation, history, and diagnostic findings to determine the most appropriate course of action.