Can Seizures Cause Miosis?
Yes, seizures can cause miosis (pupillary constriction), though this is a rare autonomic manifestation compared to the more common ictal pupillary dilation. 1, 2, 3
Evidence for Seizure-Induced Miosis
Direct Clinical Documentation
Focal seizures can present with bilateral pupillary miosis as an ictal manifestation, documented in cases where seizure onset was confirmed by concurrent EEG recordings showing focal spike activity 1, 2
A case series demonstrated miosis occurring during focal seizures originating from left centroparietal cortical dysplasia, with seizure onset coincident with EEG-confirmed epileptic activity 1
Bilateral pupillary constriction and internal ophthalmoplegia have been reported as the only physical manifestation of partial sensory seizures, with onset and offset corresponding precisely to EEG discharges in the left temporo-occipital region 2
Panayiotopoulos Syndrome: A Common Context
Miosis is specifically documented as an autonomic manifestation in Panayiotopoulos syndrome, a benign childhood epilepsy characterized by autonomic seizures 4, 3
In this syndrome, autonomic symptoms include mydriasis (more common) or miosis (less common), along with other autonomic features like emesis, pallor, and cardiorespiratory alterations 4
A prospective study found that syncope-like epileptic seizures in Panayiotopoulos syndrome were associated with concurrent autonomic symptoms including both mydriasis and miosis 3
Mechanism and Localization
The proposed mechanism involves activation of a cortical pupillary constrictive center in the temporal-occipital area, as ictal discharges in these regions can trigger parasympathetic pupillary responses 2
Seizures affecting the central autonomic network can cause various autonomic manifestations including pupillary changes, cardiovascular effects, and other autonomic dysfunction 5
Clinical Significance
Diagnostic Considerations
Miosis during a seizure is an uncommon but recognized autonomic sign that should prompt consideration of focal epilepsy, particularly when other autonomic symptoms are present 4, 3
The presence of miosis with altered consciousness, especially in children, should raise suspicion for Panayiotopoulos syndrome if accompanied by emesis, pallor, or other autonomic features 4
Important Caveats
Pupillary dilation (mydriasis) is far more common than miosis during seizures, so the absence of miosis does not exclude seizure activity 4, 5
Miosis can be mistaken for other conditions; the key is correlating pupillary changes with EEG findings and other ictal features 1, 2
In Panayiotopoulos syndrome, autonomic seizures are frequently misdiagnosed as non-epileptic conditions such as syncope, encephalitis, or gastroenteritis, leading to costly mismanagement 4