Synopsis
Choose dedicated imaging for sellar and posterior-fossa disease, recognise optic-pathway, brainstem and CSF-flow emergencies, and keep adult pituitary and age-specific posterior-fossa pathways distinct.
- Use a dedicated sellar MRI protocol with thin coronal and sagittal images to assess pituitary size, haemorrhage, stalk, cavernous sinuses and optic chiasm; a routine brain MRI can miss small lesions.
- Pituitary apoplexy is treated from the clinical endocrine and visual syndrome: obtain urgent MRI when feasible, use CT as an acute alternative and never delay indicated steroid replacement for imaging.
- Posterior-fossa interpretation follows the fourth ventricle, cerebellar hemispheres and vermis, brainstem, cisterns and foramen magnum, with special attention to CSF obstruction.
Key red flags
Sudden headache with visual loss, ophthalmoplegia, altered consciousness, hypotension or hyponatraemia suggests pituitary apoplexy and requires urgent endocrine and neurosurgical assessment.
Drowsiness, repeated vomiting, bradycardia, cranial-nerve dysfunction or worsening ataxia with a posterior-fossa lesion may indicate brainstem compression or obstructive hydrocephalus.
A child under 12 with headache plus morning waking, vomiting, ataxia, altered consciousness or squint needs same-day neurological assessment under NG127.
Do not perform lumbar puncture when posterior-fossa mass effect, obstructive hydrocephalus or neurological deterioration creates a herniation risk.
A normal or non-diagnostic CT does not exclude small sellar lesions, pituitary infarction or subtle posterior-fossa disease; persistent localising signs require MRI.
Bitemporal field loss suggests chiasmal compression, while ophthalmoplegia may reflect cavernous-sinus involvement. Document acuity, fields and ocular movements rather than saying vision affected.
Sudden headache, vomiting, reduced acuity, field loss, ocular palsy, altered consciousness and circulatory disturbance can accompany haemorrhage or infarction in a pituitary lesion.
Gait or limb ataxia, dysarthria, nystagmus, cranial-nerve deficits and long-tract signs localise to cerebellum or brainstem and can be subtle on CT.
Assess fourth-ventricular distortion, enlargement upstream, transependymal CSF seepage and basal cisterns. Clinical decline converts ventricular enlargement into an emergency.
Investigation priorities
Characterise sellar and suprasellar anatomy, optic-chiasm contact, cavernous-sinus involvement and haemorrhage or infarction.
Management branches
An adult presents with acute severe headache, ophthalmoplegia, visual deterioration and haemodynamic disturbance.
- Treat possible pituitary apoplexy as an endocrine emergency, obtain urgent safety and pituitary bloods if this will not delay treatment, and give indicated glucocorticoid replacement.
- Arrange urgent dedicated pituitary MRI as the investigation of choice, using CT when MRI is not immediately feasible, and contact endocrine and neurosurgical specialists.
A stable adult has an incidental sellar lesion and no acute apoplexy features.