The structure of the midbrain has three layers. The excitations of the sensitive midbrain nerves are transmitted from the midbrain to the cerebrum (telencephalon), where they are switched to motor nerves. The extrapyramidal system is a neurophysiological concept for all movement control processes outside the pyramidal tracts in the spinal cord. The midbrain belongs to the so-called extrapyramidal system, which cannot always be clearly separated from the pyramidal system of motion control. The eye muscles are primarily controlled in this area of the brain. The midbrain is the portion of the brain stem between the bridge (pons) and the midbrain (diencephalon). The Argyll-Robertson sign is an indication of a cerebral disorder in the midbrain, which manifests itself in a reflective pupil rigidity. This phenomenon plays a role in diseases like neurolues. A midbrain lesion cancels the light responsiveness of one or both eyes. Argyll Robertson pupil Definition, Symptoms, Cause.The Argyll Robertson pupil is a reflective pupil rigidity with intact near accommodation of the eyes.Once a person get infected, this test will always come positive because of presence of antibodies against it. This test measures the level of antibodies against cardiolipin but do not calculate level of antibiotics against treponema. When the treatment has started, it is important to perform plasma regain test. Medication therapy of syphilis include intravenous administration of penicillin doxycycline and tetracycline can be administered instead of penicillin. Most of the time, its leading cause is syphilis, which should be treated 1st. Treatment regarding Argyll Robertson pupil is not discovered yet but its underlying cause must be treated to cure it. Atrophy and depigmentation are also reported as rare causes. If it occurs secondary to syphilis, then pupil generally appears to be unequal and irregular. This area involves pupillary fibers which are responsible for reflecting light. Scientist believe that roastal midbrain present in vicinity of cerebral aqueduct of third ventricle is the main area of damage regarding Argyll Robertson pupil. The Argyll Robertson pupil results in lesion to the pretectal nuclei in the mid brain. The main mechanism or etiology is still unclear but it can occurs secondary to many diseases like syphilis. It is similar to near sightedness in which far vision is blurred and near vision is accurate. Vision is effected and patient is not able to see distinct objects but can see nearly placed objects. Other symptoms reported are iris atrophies along with loss in its radial folds. The abnormal functioning of pupil starts with a very sluggish response to direct light and this abnormal response to direct light leads it towards complete loss of reflection to light. Some scientist believe that the rostal midbrain in the vicinity of the sylvian aqueduct of the 3rd ventricle is area of damage.Īrgyll Robertson pupil shows consistent pupillary findings with the passage of time from months to years. Pathophysiology behind Argyll Robertson pupil is not clear yet. This condition was 1st described by a scientist named Douglas Argyll and named this disease after his own name. As miotic pupil occurs due to lesion in dorsally placed fibers which are responsible for light response. The pupil better respond to accommodation as compare to stimulus of light. The diagnostic test of Argyll Robertson pupil does not require any special equipment and can be diagnosed easily. It is considered a neurological disorder biomarker like in neurosyphilis, neuro sarcoidosis and multiple sclerosis. This reaction of pupil is a way to confirm the functionality of the optic nerve pathway. Its been more than a century, this condition is describing. Argyll Robertson pupil is a miotic pupil which cannot reflect to direct light but efforts towards accommodate light. It is a symptom of tabetic neurosyphilis. There is a loss of pupillary reflex to direct light and have normal constriction of pupil while seeing near objects. Argyll Robertson pupil is a type of reflex iridoplegia along with miosis and irregular shape.
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