The size of the pupil and its reaction to light can indicate where the lesion is most likely to be located. An oculomotor injury can be the consequence of lesions located anywhere from the oculomotor nucleus in the midbrain to the termination of the third cranial nerve in the extraocular muscles within the orbit. Unfortunately, the pathological basis of isolated 3cnP has been poorly described in previous reports. In terms of clinical presentation, it can be found in combination with other cranial nerve deficits (particularly VI, V, and VI), can be unilateral or bilateral, and can be transient or permanent. Isolated 3cnP is very rare its incidence ranges from 8 to 16%, depending on the clinical series. Isolated 3cnP can be found in the absence of posttraumatic space-occupying mass lesion, yet it is often considered as a devastating prognostic factor in the context of diffuse axonal injury (DAI). 3cnP represents a worrying neurological sign because it is often associated with an expanding mass lesion, such as extradural or subdural haematomas. Third cranial nerve (oculomotor) palsy (3cnP) is seen in all grades of traumatic brain injury (TBI), either immediately after the traumatic event or evolving hours to days after it. ![]() Nonetheless, even when an overall good neurological outcome is achieved, recovery of isolated 3cnP is dismal, and only rarely the visual deficit completely resolves. ![]() Our experience corroborates data from the literature showing that, even in Grade III DAI, prompt recognition of isolated 3cnP can guide adequate treatment. Understanding the exact mechanism underlying the onset of 3cnP is key to provide an informed clinical decision-making to the patients and ensure their best chances of recovery. Through the analysis of five exemplificative cases and a thorough review of the literature, we identified four possible mechanisms leading to 3cnP: (1) a partial rootlet avulsion at the site of exit from the midbrain, representing a direct shearing injury to the nerve (2) a direct traction injury due to the nerve stretching against the posterior petroclinoid ligament at the base of the oculomotor triangle secondary to the downward displacement of the brainstem at the time of impact (3) a direct vascular compression as a result of internal carotid artery (ICA) dissection or pseudoaneurysm (4) an indirect injury caused by impaired blood supply to the third nerve in addition to the detrimental biochemical effects of the underlying brain injury itself. Other medicines that get in the eyes, including medicine from asthma inhalers, can change pupil size.Third cranial nerve palsy (3cnP) following traumatic brain injury (TBI) is a worrying neurological sign and is often associated with an expanding mass lesion, such as extradural or acute subdural haematomas. The use of eye drops is a common cause of a harmless change in pupil size. Unequal pupil sizes of more than 1 mm that develop later in life and do not return to equal size may be a sign of an eye, brain, blood vessel, or nerve disease. If there are no other symptoms and if the pupils return to normal, then it is nothing to worry about. If other family members also have similar pupils, then the pupil size difference could be genetic and is nothing to worry about.Īlso, for unknown reasons, pupils may temporarily differ in size. Most often, the diameter difference is less than 0.5 mm, but it can be up to 1 mm.īabies born with different sized pupils may not have any underlying disorder. Slight differences in pupil sizes are found in up to 1 in 5 healthy people. ![]() ![]() It gets larger in dim light and smaller in bright light. The pupil is the black part in the center of the eye. Anisocoria Enlargement of one pupil Pupils of different size Eyes/pupils different sizeĪnisocoria is unequal pupil size.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |