3/13/2023 0 Comments Image of unequal pupil size![]() Disorders of pupillary function, accommodation and lacrimation. Critical evaluation of the cocaine test in the diagnosis of Horner's syndrome. Kardon RH, Denison CE, Brown CK, Thompson HS.Walsh & Hoyt's Clinical Neuro-ophthalmology. A flow chart for sorting out the anisocorias. Horner's syndrome, Pseudo-Horner's syndrome, and simple anisocoria. In: Walsh and Hoyt Clinical Neuro-ophthalmology, 6th ed, Miller, NR, Newman, NJ, Biousse, V, Kerrison, JB (Eds), Williams & Wilkins, Baltimore 2005. Principles and techniques of examination of the pupils, accommodation and lacrimation. Intracranial sympathetic pathways associated with the sixth cranial nerve. Neuro-Ophthalmology Illustrated, Thieme Verlag, Germany 2009. Prevention: There are many causes, of which some are unpreventable, but traumatic causes may be prevented with appropriate protective gear.The benign causes require no treatment at all. Treatment: This is highly dependent on the cause of the anisocoria. ![]() In the benign type it is advisable to look at older pictures, such as drivers licences (with a magnifying glass) to see if it has always been there (and it usually is). Diagnosis: This will depend on the history and presentation.There may also be double vision or a droopy eye lid. If symptoms are present they are usually of the associated cause, such as a brain tumour. A common cause could be inside the eye, due to previous surgery or trauma. This can range from infections of the nerves to masses pushing on the nerve. Cause: The causes are numerous, but there is usually damage to the nerve that supplys the muscle that either make pupil bigger or smaller.There is a large proportion of the population that has a benign form which is usually noticed incidentally. The causes a numerous from non-life threatening to threatening ones. Definition: Anisocoria is the presence of unequal pupils.The fibres then travel with the fifth cranial nerve and innervate the dilator muscle and the Mueller muscle. The third order neuron then ascends with the carotid artery to the lateral sellar compartment, where it travels near the sixth nerve. The second order neuron travels upward the cervical spine via the brachial plexus and over the apex of the lung to the cervical (superior) ganglion, near the bifurcation of the carotid. The first order neuron descends down to the spinal cord to the T2 level. Dilatation is mediated by sympathetic outflows that originate from the hypothalamus. This is primarily transferred via parasympathetic fibres that originate from the Edinger-Westphal subnucleus of cranial nerve III in the midbrain. Other factors such as the sympathetic tone and may also influence the pupil size.Ĭonstriction is mediated by increasing light and near vision. Pupillary size is determined by a balance between the dilator and sphincter muscles and by reflex actions that are responsive to light. The pathophysiology depends on the underlying cause and an injury in either the dilator or constrictor pathway may cause anisocoria. The imaging modality will depend on the suspected etiology. Third nerve palsies should be presumed compressive if there is a pupillary involvement. For suspected Horner’s syndrome a magnetic resonance imaging (MRI) or angiography may be required. Imaging studies will dependent on the possible cause. Possible exposures should be found. Mechanical cause have an obvious history such as trauma and surgery. Conditions such as third nerve palsy have to be examined. The pharmacologic pupil is larger than most other causes of anisocoria and there is poor response to light. If the anisocoria is greater in light then the number of differentials is increased. If the test show no lag and there are no other features then it is most likely diagnosis is physiological. Cocaine dilates the normal pupil but not the affected pupil, in syndromes such as Horner’s syndrome. If the anisocoria is greater in the dark, then the dilation lag cocaine test is done. First the affected pupil is identified by using the method as detailed above.
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