From the Research
Pontine lesions typically present with pinpoint pupils, which are small, equal, and reactive to light, due to damage to the sympathetic pathways while preserving parasympathetic function. The location and extent of the lesion can affect the pupillary findings, with lateral pontine lesions potentially causing Horner's syndrome (miosis, ptosis, and anhidrosis) on the same side as the lesion 1. In cases of extensive pontine damage, such as pontine hemorrhage or "locked-in syndrome," bilateral pinpoint pupils are typically present, which may still retain some reactivity to light despite their small size.
When evaluating a patient with a pontine lesion, it is essential to consider the potential impact on the pupil, as well as other ocular movement abnormalities, such as horizontal gaze palsy, which can be a rare presentation of multiple sclerosis 1. The presence of pinpoint pupils in a comatose patient should raise suspicion for a pontine lesion, opioid overdose, or organophosphate poisoning, requiring immediate neurological evaluation and management of the underlying cause.
Key points to consider in the evaluation of pontine lesions and their impact on the pupil include:
- The location and extent of the lesion can affect the pupillary findings
- Lateral pontine lesions can cause Horner's syndrome on the same side as the lesion
- Extensive pontine damage can result in bilateral pinpoint pupils
- Ocular movement abnormalities, such as horizontal gaze palsy, can be a presentation of multiple sclerosis 2, 1
- The presence of pinpoint pupils in a comatose patient requires immediate neurological evaluation and management of the underlying cause.