Pupillary Response - an overview | ScienceDirect Topics

Neurologic examination is a broad term that encompasses many aspects of the nervous system. It may include the evaluation of reflexes, motor function, sensory perception, and cognitive function. The neuro exam is often conducted at the beginning of a patient’s visit with their doctor or healthcare provider to help diagnose conditions such as stroke, spinal cord injury, and brain injuries.

However, pupillary evaluation is one of the most commonly performed neurological examinations because it is easy to perform and can be done quickly. It’s also a highly reliable test of the function of the autonomic nervous system and is often used to screen for brainstem or cerebellar dysfunction.

A critical aspect of this pupil evaluation is the percent change in pupil size. In this article, we’ll explain why this is important, how it can help diagnose brainstem damage and the standard limits for pupil size.

What Does the Percent Change in Pupil Size Mean?

There is an interesting relationship between the brain and the eyes. As such, when there is a problem in one, it can often be reflected in the other. This relationship becomes even more significant when considering how the brainstem connects to both.

The brainstem is a collection of neural tissue that sits at the base of the spinal cord and connects it to the eyes and sensory organs, like those in the face and ears.

It is responsible for things like breathing, heartbeat, and blood pressure. This makes it an essential structure in the body but one that can easily be damaged by trauma or disease. When there is damage to this region, it can lead to problems with eye movement and pupil size.

The percent change in pupil size is crucial because it can indicate how much damage has been done to the brainstem. A large decrease in pupil size suggests that there has been significant trauma or injury to this region and that more severe problems are likely to follow.

How Can the Percent Change in Pupil Size Help Doctors to Make a Diagnosis?

If a patient suffers from a TBI, measuring their pupillary response in traumatic brain injury means that doctors can understand how severe their injury is. If the pupil size changes dramatically, it suggests that there has been significant damage to this region and that further testing may be needed.

The percent change in pupil size can also help doctors diagnose patients who are in a coma and cannot communicate in any other way. If a patient’s pupils are small and do not respond to light, this indicates that there is likely damage to the brainstem and that more severe problems may be on the horizon.

What Neurological Tools Can Doctors Use for Checking the Percent Change in Pupil Size?

Every neurological exam relies on several neurological tools to help doctors perform their diagnosis. The most common tool is an ophthalmoscope, which allows doctors to look into the eye and see what’s happening inside it.

Other tools include reflex hammers, which can be used to test reflexes in the body; tuning forks, which measure the vibration frequency of sound waves; and electroencephalograms (EEGs), which measure electrical activity in the brain by placing electrodes around the head.

But the best tool for neurologic exams is the NPi pupilometer. This tool relies on the fact that the pupils of a person’s eyes are directly related to their neurological health. If a person has brain damage, their pupils will be constricted (small) since they can no longer dilate them. Pupils can also tell doctors if a patient is suffering from nerve damage; if so, the pupil will be dilated (large).

The pupilometer is fast and accurate and can be used in various situations — including at the scene of an accident or during an examination. The pupilometer is also noninvasive; no needles or other invasive tools are required, and it takes only seconds to use.

Finally, with the pupilometer, doctors don’t necessarily need the patient to be conscious. The pupilometer is the ideal tool for a doctor to quickly and accurately determine if someone has nerve damage. It’s also straightforward to use; all it takes is a glance at the eye.

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