A concussion is a mild traumatic brain injury resulting from a jolt or blow to the head or body that causes the brain to move rapidly within the skull. This movement can disrupt normal brain function, leading to a variety of symptoms. While concussions are generally not life-threatening, their effects can range from temporary to more prolonged, impacting how a person thinks, feels, and acts. Some concussion symptoms can also affect the eyes and vision.
Pupil Changes After Concussion
Pupil changes can occur after a concussion, but dilation is not the only or most common response. While pupils may dilate, they can also exhibit other alterations like constriction, slow reaction to light, or unequal size (anisocoria). Approximately 90% of individuals with a concussion may experience some form of eye-related symptoms. These pupil changes are important indicators of head injury, but their presence alone does not exclusively confirm a concussion, as other factors can influence pupil size.
How Concussions Affect Pupils
Concussions disrupt the brain’s normal functioning, including areas that control involuntary actions like pupil size. This disruption can involve the autonomic nervous system, which regulates many bodily functions without conscious effort. The sympathetic branch causes pupils to dilate, while the parasympathetic branch controls constriction. An impact from a concussion can affect the brainstem, which plays a role in controlling pupil size. The oculomotor nerve, also known as the third cranial nerve, is crucial for pupil constriction; its function can be temporarily impaired, leading to delayed, slowed, or reduced pupillary responses.
Interpreting Pupil Changes
Different types of pupil changes carry distinct significance after a head injury. Unequal pupils, or anisocoria, where one pupil is noticeably larger than the other, can indicate a structural brain injury or pressure on certain nerves. Sluggish reaction to light, where pupils are slow to constrict when exposed to brightness, or fixed pupils that do not react, are also important signs. These observations are part of a broader set of concussion symptoms and are important for medical assessment. However, individuals should not attempt to self-diagnose based solely on pupil changes.
When to Seek Urgent Care
Immediate medical attention is necessary if certain pupil changes or other severe symptoms appear after a head injury. Urgent care is warranted if one pupil is larger than the other, or if pupils do not react to light. Other concerning symptoms include a worsening headache, repeated vomiting, increasing drowsiness, seizures, and slurred speech. Any loss of consciousness, even brief, also requires prompt medical assessment. Professional medical evaluation is important for any suspected concussion, particularly if eye or vision changes are observed.