Differential Diagnosis for Sustained Clonus and Decreased GCS

Single Most Likely Diagnosis

• Hypoxic-Ischemic Encephalopathy: This condition is a common cause of decreased Glasgow Coma Scale (GCS) and can lead to sustained clonus due to the brain's attempt to compensate for the lack of oxygen. The justification for this diagnosis is the direct impact of hypoxia on brain function, which can result in a range of neurological deficits.

Other Likely Diagnoses

• Status Epilepticus: Prolonged seizure activity can cause sustained clonus and a decrease in GCS. The ongoing seizure activity can lead to brain injury, further decreasing the patient's level of consciousness.
• Traumatic Brain Injury (TBI): A severe head injury can result in decreased GCS and sustained clonus due to the mechanical damage to brain tissue. The injury can disrupt normal brain function, leading to a variety of neurological symptoms.
• Metabolic Encephalopathy: Conditions such as hepatic encephalopathy or sepsis can cause alterations in mental status, including a decrease in GCS, and can lead to sustained clonus due to the toxic effects on the brain.

Do Not Miss Diagnoses

• Meningitis or Encephalitis: Infections of the brain or meninges can present with decreased GCS and sustained clonus. These conditions require prompt diagnosis and treatment to prevent serious complications or death.
• Subarachnoid Hemorrhage: A sudden bleed into the space surrounding the brain can cause a decrease in GCS and lead to sustained clonus. Early detection is crucial for effective management.
• Cerebral Vasculitis: Inflammation of the blood vessels in the brain can result in a range of neurological symptoms, including decreased GCS and sustained clonus. This condition can be life-threatening if not promptly treated.

Rare Diagnoses

• Creutzfeldt-Jakob Disease: A rare, degenerative, fatal brain disorder that can cause a rapid decline in neurological function, including a decrease in GCS and sustained clonus.
• Hashimoto's Encephalopathy: A rare condition associated with autoimmune thyroiditis, which can cause encephalopathy, including decreased GCS and neurological symptoms like sustained clonus.
• Whipple's Disease: A rare, systemic bacterial infection that can affect the brain, leading to a decrease in GCS and various neurological symptoms, including sustained clonus.