Posterior reversible encephalopathy syndrome

Hypertensive emergency is severe hypertension (usually above 180/120 mmHg) with acute target-organ damage such as encephalopathy, stroke, acute heart failure, myocardial ischemia, aortic dissection, or acute kidney injury. It requires controlled intravenous blood pressure reduction, with the target and pace determined by the specific end-organ involved.

New-onset hypertension after 20 weeks of gestation with proteinuria or end-organ dysfunction, driven by abnormal placental spiral artery remodeling and widespread endothelial dysfunction. Eclampsia is preeclampsia complicated by seizures; magnesium sulfate treats and prevents seizures, and prompt delivery is the only definitive cure for both.

Reversible cerebral vasoconstriction syndrome (RCVS) is recurrent thunderclap headache with multifocal constriction of intracranial arteries that normalizes within 3 months, usually triggered by vasoactive drugs or the puerperium, and it is the second most frequent cause of thunderclap headache after subarachnoid hemorrhage. Diagnosis follows noncontrast CT, lumbar puncture, and MRA or CTA; treatment is removal of the trigger, blood pressure control, and verapamil, with glucocorticoids and triptans avoided.

Thrombosis of the dural venous sinuses or cortical veins that impairs cerebral venous drainage and CSF absorption, producing headache, papilledema, focal deficits, or seizures; MRI/MRV or CT venography establishes the diagnosis, and anticoagulation is first-line even when hemorrhagic venous infarction is present.

Subarachnoid hemorrhage is sudden bleeding into the subarachnoid space, most often from a ruptured saccular (berry) aneurysm, presenting as the worst headache of a patient's life. Diagnosis is noncontrast head CT, then lumbar puncture if CT is negative, then catheter angiography to define the aneurysm; management is early aneurysm securement, blood pressure control, and nimodipine to reduce delayed cerebral ischemia from vasospasm.

Spontaneous bleeding into brain parenchyma, most often from chronic hypertension affecting deep penetrating vessels or from cerebral amyloid angiopathy in lobar locations, diagnosed by noncontrast CT and managed with acute blood pressure lowering, reversal of anticoagulation, and surgical evacuation for select cerebellar or deteriorating hemorrhages.

Status epilepticus is a generalized tonic-clonic seizure lasting more than 5 minutes, or repeated seizures without return to baseline, and is a neurologic emergency. Treatment is a timed escalation: IV benzodiazepine first, then an IV antiepileptic drug, then anesthetic coma with continuous EEG if convulsions persist.

A first or provoked seizure requires a focused history to distinguish it from syncope or a nonepileptic event, urgent glucose and electrolyte testing, brain MRI, and outpatient EEG; an unprovoked seizure with normal imaging and EEG usually does not require antiepileptic drug therapy, since epilepsy is defined only after a second unprovoked seizure or a high-risk first one.

Progressive multifocal leukoencephalopathy is an opportunistic demyelinating brain infection caused by reactivation of JC virus in significantly immunosuppressed patients, most often with AIDS or on natalizumab, rituximab, or other immunomodulators. Diagnosis rests on MRI white matter lesions plus CSF JC virus PCR; there is no antiviral treatment, so management is restoring immune function.

Solid organ transplant complications arise from the immunosuppression that prevents graft rejection, producing a predictable, time-dependent pattern of rejection, opportunistic infection, and malignancy. Diagnosis rests on allograft biopsy and pathogen-specific testing, and first-line treatment pairs targeted therapy of the complication with a deliberate adjustment, not blanket discontinuation, of the immunosuppressive regimen.

In adults, brain metastases (lung, breast, kidney, melanoma) are the most common intracranial tumors, meningioma is the most common primary tumor, and glioblastoma multiforme is the most aggressive primary glioma. Management combines resection when feasible, radiation, and chemotherapy (temozolomide for glioblastoma, methotrexate-based regimens for CNS lymphoma) with corticosteroids and antiepileptics for symptom control.