You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Eye examination of a patient revealed lack of upward gaze and dilated pupils fixed to light. What is the MOST probable location of the lesion? and explain in detail?
In a patient with lesion of the superior colliculus, there is loss of upward gaze associated with dilated pupils that are fixed to light. Lesions in the collicular region is caused by pressure and distoion of underlying structures in the midbrain and not by damaged to specific pathways traversing the colliculi. It can produce any combination of impaired upward gaze, impaired downward gaze, pupillary abnormalities or loss accommodation reflex can occur. The general name for the clinical picture produced is called Perinaud's syndrome. Ref: Textbook of Ophthalmology edited by Sunita Agarwal, page 284.