Neurology

Bell's palsy is an acute idiopathic unilateral peripheral facial-nerve palsy; forehead involvement and isolated lower-motor-neurone weakness support the diagnosis, but eye protection and exclusion of stroke, Ramsay Hunt syndrome and other causes are essential.

A brain abscess is a focal intracranial collection of infected material that combines a deep infection with an expanding mass, requiring urgent neurosurgical, infectious-disease and source-control management.

Brain tumours are primary or metastatic intracranial neoplasms that can present through seizures, progressive focal dysfunction or raised intracranial pressure; diagnosis and treatment depend on imaging, tissue, molecular profile, site and performance status.

Cerebral venous sinus thrombosis is thrombosis of a dural venous sinus or cerebral vein that obstructs venous drainage, causing raised intracranial pressure, venous infarction, haemorrhage, seizures and focal or diffuse neurological dysfunction.

A syndrome of acquired cognitive and functional decline whose cause must be established through longitudinal history, collateral information, examination and targeted investigation, with delirium and treatable contributors addressed first.

Encephalitis is inflammation of the brain parenchyma causing altered mental state, seizures or focal neurological dysfunction, usually from infection or autoimmunity; suspected herpes-simplex encephalitis needs immediate empirical intravenous aciclovir while investigations are arranged.

A disorder of enduring susceptibility to recurrent seizures caused by abnormal, hypersynchronous electrical activity in brain networks; diagnosis is clinical, seizure type determines treatment, and prolonged or repeated seizures are emergencies.

Essential tremor is an isolated, usually bilateral upper-limb action tremor lasting at least 3 years, diagnosed clinically after characterising the tremor and excluding parkinsonism, dystonia, ataxia, drugs and systemic causes.

An acute immune-mediated polyradiculoneuropathy causing progressive symmetrical weakness, areflexia and potentially rapid respiratory or autonomic failure.

Metastatic spinal cord compression is compression of the spinal cord or cauda equina by malignant disease and an oncological emergency; progressive spinal pain, gait change, weakness, sensory loss or bladder/bowel symptoms in someone with current or previous cancer need immediate MSCC-pathway escalation.

Motor neurone disease (MND) is a progressive neurodegenerative syndrome affecting upper and lower motor neurones, usually with preserved sensation and eye movements but possible cognitive, behavioural, bulbar and respiratory involvement; suspected MND needs prompt specialist assessment and coordinated multidisciplinary care.

A chronic immune-mediated disease of the central nervous system causing neurological lesions and symptoms that are disseminated in space and time; diagnosis is specialist-led, relapses and progression must be distinguished, and disease-modifying therapy is selected according to disease activity.

An autoimmune neuromuscular-junction disorder causing fluctuating, fatigable weakness with particular risk to ocular, bulbar and respiratory muscles.

A progressive neurodegenerative disorder causing bradykinesia with rigidity or tremor, usually asymmetrically at onset, with treatment focused on individualised motor control, non-motor symptoms, rehabilitation, safe medicines and future planning.

Peripheral neuropathy is dysfunction of one or more peripheral nerves; the common chronic form is a length-dependent distal polyneuropathy, but focal, multifocal, autonomic, demyelinating and acute patterns require different investigation and urgency.

Radiculopathy is dysfunction of a spinal nerve root causing radiating pain, sensory change, weakness or reflex loss in a root distribution; most lumbar sciatica improves with conservative care, but cauda equina, cord compression, progressive deficit, infection and malignancy require urgent escalation.

Raised intracranial pressure is a dangerous final pathway in which increased volume within the fixed skull reduces cerebral perfusion and may cause herniation; the cause, visual risk and speed of neurological deterioration determine the emergency pathway.

Spinal cord injury disrupts motor, sensory and autonomic pathways below a lesion; early priorities are spinal protection, oxygenation, perfusion and specialist trauma care, with neurogenic shock and autonomic dysreflexia as key emergencies.

Convulsive status epilepticus is a self-sustaining seizure state in which gamma-aminobutyric acid (GABA) inhibition fails, so seizures no longer stop spontaneously and grow harder to treat every minute.

Sudden focal neurological loss from arterial occlusion or vessel rupture: occlusion leaves a dying core around which viable brain can still be rescued, rupture makes any antithrombotic dangerous.

A transient focal neurological syndrome caused by cerebral, spinal or retinal ischaemia without acute infarction; symptoms may resolve quickly, but the event is a medical warning that requires immediate aspirin and specialist assessment within 24 hours.

Trigeminal neuralgia causes recurrent, brief, severe electric-shock-like facial pain triggered by innocuous stimuli; diagnose the phenotype clinically, investigate atypical or secondary features, offer carbamazepine first-line and refer early when treatment fails or procedures may be needed.

Wernicke-Korsakoff syndrome is a spectrum of thiamine deficiency: acute Wernicke's encephalopathy is a treatable medical emergency, while Korsakoff's syndrome is a chronic amnesic disorder requiring abstinence support, rehabilitation and tailored long-term care.