<prompt> Transtentorial uncal herniation causes all except :Ipsilateral dilated pupilsIpsilateral hemiplegiaCheyne stokes respirationDecoicate rigidity  <response>: Answer is D Decoicate rigidity: Decoicate rigidity is not seen as a manifestation of uncal herniation. All other features form pa of the spectrum. Herniation or coning is said to be occurring when pa of the brain is forced through a rigid hole. Uncal herniation Central herniation The uncus and the temporal lobe are forced through the cerebellar tentorium tentorium that separates the cerebrum from the cerebellum The diencephation i.e. the thalamus and related structures that lie between upper brainstem and cerebral hemispheres are forced through the tentorium. What happens What happens Sequential compression occurs of the - Ipsilateral third nerve Sequential compression occurs of the - Upper midbrain first - Contralateral brainstem later - Pons later - Whole brainstem eventually - Medulla finally Physical signs Physical signs Early Later Still later Early Later Still later IL dilated pupils IL hemiplegia Tetraparesis Errotic respiration Cheyne Fixed Signs of supra Progressive ptosis Be fixed dilated Small reactive pupils. stokes dilated xentorial mass third n palsy pupils Increased limb tone respiration pupils lesions Cheyne- stokes Erratic respiration Bilateral extensor Decoicate Deccrebrate respiration Death plantar rigidity posturing 