Differential Diagnosis for Pinpoint Pupils
Single Most Likely Diagnosis
- Opioid use or overdose: This is the most common cause of pinpoint pupils due to the opioid's effect on the parasympathetic nervous system, which causes pupillary constriction.
Other Likely Diagnoses
- Pontine stroke: A stroke affecting the pons in the brainstem can lead to pinpoint pupils due to damage to the pupillary constriction pathways.
- Neurosyphilis: This condition can cause Argyll Robertson pupils, which are small and do not react to light but constrict during accommodation.
- Diphtheria: This bacterial infection can lead to neurotoxic effects, including pupillary constriction.
Do Not Miss Diagnoses
- Subarachnoid hemorrhage: Although less common, a subarachnoid hemorrhage can cause pinpoint pupils due to increased intracranial pressure and brainstem compression.
- Status epilepticus: Prolonged seizure activity can lead to various neurological signs, including pupillary abnormalities.
- Brainstem tumor: Tumors in the brainstem can compress or invade structures controlling pupillary size, leading to pinpoint pupils.
Rare Diagnoses
- Familial amyloid polyneuropathy: A rare genetic disorder that can affect the autonomic nervous system, leading to pupillary constriction among other symptoms.
- Mitochondrial myopathies: Certain mitochondrial disorders can affect the muscles of the eye, leading to abnormalities in pupillary size and reactivity.
- Holocord syrinx: A rare condition where a fluid-filled cavity forms within the spinal cord, potentially affecting autonomic functions, including pupillary control.