Features of tentorial herniation include

. *trans tentorial herniation of the uncus may compress the ipsilateral 3rd nerve and usually involves the pupillary fibres first ,causing a dilated pupil :however ,a false localised contralateral 3rd nerve palsy may also occur ,perhaps due to extrinsic compression by the tentorial margin.vomiting,coma,bradycardia and aerial hypeension are later features. Ref Harrison20th edition pg 2345