Focal limb weakness

Focal limb weakness is reduced muscle power affecting one limb or one side of the body (monoparesis, hemiparesis) with onset over minutes to days. The second is to localise the lesion from the cortex to the muscle.

Clinical relevance. Acute stroke treatment depends on the interval from onset. Thrombolysis is time limited and thrombectomy needs rapid imaging.

Anatomy and localisation. Hemiparesis with facial involvement points above the pons (cortex, corona radiata, internal capsule). A pure motor hemiparesis is typical of a lacunar infarct. Crossed signs (ipsilateral cranial nerve palsy with contralateral limb weakness) point to the brainstem. Weakness of one leg with a contralateral loss of pain and temperature points to a hemicord lesion (Brown Sequard syndrome). Monoparesis with root, plexus or nerve territory deficits indicates a lower motor neuron cause.

Upper versus lower motor neuron. Upper motor neuron weakness shows spasticity, brisk reflexes, extensor plantars and a pyramidal pattern (extensors in the arm, flexors in the leg). Lower motor neuron weakness shows wasting, fasciculation, hypotonia and reduced reflexes.

Temporal patterns. Sudden (stroke, haemorrhage, hypoglycaemia, post-ictal paresis, migraine), hours to days (demyelination, infection, abscess, subdural haematoma, neuropathy), subacute (tumour, mononeuropathy, vasculitis).

History. Exact time of onset or time last known well (record clock time), speed of onset, associated headache, vomiting, speech or visual change, facial droop, sensory symptoms, seizure, neck pain or trauma, palpitations, chest pain, fever, back pain, recent surgery, pregnancy or postpartum, prior similar episodes, and baseline function. Ask whether the patient woke with symptoms.

Risk factors and drug history. Hypertension, atrial fibrillation, diabetes, smoking, dyslipidaemia, previous stroke or transient ischaemic attack, carotid or heart valve disease, endocarditis risk, injecting drug use, cancer, HIV, sickle cell disease, migraine, oral contraceptives, anticoagulants and antiplatelets, thrombophilia, recent head or neck manipulation, cocaine and amphetamines, and recent dental procedures.

Examination.

• Vital signs, blood pressure in both arms, pulse rhythm, capillary glucose, temperature, oxygen saturation.
• Neurological: Glasgow Coma Scale, National Institutes of Health Stroke Scale (0 to 42; scores over 15 indicate severe stroke), face, arm and speech test, language, neglect, visual fields, eye movements, pupils, facial power, limb power at each joint, tone, reflexes, plantar responses, coordination, gait, and sensation.
• Cardiovascular: murmurs, carotid bruits, irregular pulse, signs of endocarditis, peripheral emboli.
• Spine: tenderness, sensory level, bladder distension, anal tone.
• Skin: rash, vesicles, livedo reticularis.
• Breath and head: head injury signs, tongue bite, neck stiffness.

Red flags

• Onset within the last 4.5 hours, or time last known well within 24 hours (any large vessel occlusion features: gaze deviation, severe weakness, neglect, aphasia)
• Reduced consciousness, severe headache, vomiting, or seizure at onset
• Fever, neck stiffness, spinal pain or a sensory level
• Anticoagulant use or head injury
• Pregnancy or postpartum, or young age without risk factors
• Bilateral signs, or rapidly progressing weakness
• Cancer, HIV, or immunosuppression
• Hypoglycaemia or hyperglycaemia

Special groups. Pregnancy and postpartum: cerebral venous thrombosis, reversible cerebral vasoconstriction, pre-eclampsia, thrombotic thrombocytopenic purpura. Young adults: dissection, patent foramen ovale, sickle cell disease, thrombophilia, drugs. Children: sickle cell, moyamoya disease, arteriopathy. Region specific: neurocysticercosis, tuberculoma, cerebral malaria, rheumatic and Chagas heart disease as embolic sources, and HIV related stroke.

Cerebral and brainstem vascular

• Ischaemic stroke: large artery atherosclerosis, cardioembolism (atrial fibrillation, valve disease, endocarditis, myocardial infarction, atrial myxoma), small vessel lacunar infarct, cervical artery dissection, vasculitis, hypercoagulable states, moyamoya disease, sickle cell disease, cerebral venous sinus thrombosis
• Transient ischaemic attack
• Intracerebral haemorrhage, subarachnoid haemorrhage, subdural and extradural haematoma
• Hypertensive encephalopathy and posterior reversible encephalopathy syndrome
• Cerebral amyloid angiopathy

Structural and infective

• Brain tumour (primary or metastatic), abscess, tuberculoma, neurocysticercosis, toxoplasmosis, progressive multifocal leukoencephalopathy
• Subdural empyema, meningoencephalitis

Inflammatory and demyelinating

• Multiple sclerosis, acute disseminated encephalomyelitis, neuromyelitis optica spectrum disorder, CNS vasculitis, neurosarcoidosis

Spinal and lower motor neuron

• Hemicord lesion (Brown Sequard syndrome), cervical myelopathy with root compression, disc prolapse
• Brachial or lumbosacral plexopathy (neuralgic amyotrophy, diabetic amyotrophy)
• Mononeuropathy: radial, ulnar, median, common peroneal, femoral; mononeuritis multiplex
• Radiculopathy, motor neuron disease (focal onset)

Other

• Todd paresis after seizure, hemiplegic migraine
• Hypoglycaemia (can cause hemiparesis), hyperglycaemia
• Hypokalaemia or hyperkalaemia with unilateral presentation (rare)
• Myasthenia gravis and myopathy (usually bilateral), inflammatory myopathy
• Functional weakness (Hoover sign: weak hip extension that returns with contralateral hip flexion against resistance; hip abductor sign)
• Complex regional pain syndrome, arthritis, musculoskeletal pain limiting effort
• Compartment syndrome and arterial occlusion causing a weak, cold limb

Reasoning. Treat sudden focal weakness as a stroke until imaging says otherwise. Check glucose, secure time of onset, scan, and decide on reperfusion within minutes. Then determine the mechanism to direct secondary prevention. For gradual presentations, localise first.

Immediate tests (within 10 minutes). Capillary glucose, blood pressure, ECG, oxygen saturation, temperature.

Imaging.

• Non-contrast CT head immediately (haemorrhage excluded, early ischaemic change). CT angiography of head and neck and CT perfusion (or MRI with diffusion and perfusion) when thrombectomy is possible; selection extends the treatment window to as late as 24 hours from last known well in patients with salvageable tissue.
• MRI with diffusion weighted imaging detects small, posterior fossa and early infarcts that CT misses; use when the diagnosis is unclear, in young patients, and for suspected demyelination, abscess, venous thrombosis (with venography) or tumour.
• MRI spine urgently for spinal pain, sensory level or bladder symptoms.

Blood tests. Full blood count, urea, electrolytes, creatinine, glucose, HbA1c, lipids, clotting (international normalised ratio, activated partial thromboplastin time), troponin, ESR and C reactive protein, blood cultures if febrile, group and save, and in selected cases thrombophilia and autoimmune screening, HIV and syphilis serology, haemoglobin electrophoresis, toxicology.

Cardiac and vascular work up. 12 lead ECG, continuous cardiac monitoring for at least 24 hours (longer prolonged ambulatory monitoring or implantable loop recorder for cryptogenic stroke to find atrial fibrillation), echocardiography (transthoracic first, then transoesophageal or bubble study when indicated), carotid duplex or CT angiography.

Lumbar puncture (after imaging) for suspected meningitis, encephalitis, demyelination or vasculitis; subarachnoid haemorrhage with a negative CT.

Neurophysiology. Nerve conduction studies and electromyography for plexus, nerve, root or motor neuron disease.

Limitations. Early CT is often normal in ischaemic stroke, and infarcts in the posterior fossa may be missed. Stroke mimics (hypoglycaemia, seizures, migraine, functional weakness) account for a notable minority and should not delay imaging.

Immediate care. Airway, breathing and circulation. Oxygen only when saturation is under 94 percent. Treat hypoglycaemia (glucose under 4 mmol/L: 10 percent glucose 150 to 200 mL IV over 15 minutes, repeated until over 4 mmol/L). Keep nil by mouth until swallow screening is done. Treat hyperthermia (paracetamol 1 g every 6 hours, maximum 4 g in 24 hours). Avoid hypotension and treat hyperglycaemia (target 7.8 to 10 mmol/L).

Acute ischaemic stroke

• Intravenous thrombolysis within 4.5 hours of onset once haemorrhage is excluded and exclusion criteria are checked. Alteplase 0.9 mg/kg IV (maximum 90 mg): 10 percent as a bolus over 1 minute and the remainder over 60 minutes. Alternative: tenecteplase 0.25 mg/kg IV as a single bolus (maximum 25 mg).
• Main exclusions: any intracranial haemorrhage, recent major surgery or serious trauma within 14 days, gastrointestinal or urinary tract haemorrhage within 21 days, previous intracranial haemorrhage, international normalised ratio over 1.7, platelet count under 100 x 10^9/L, glucose under 2.7 mmol/L, use of a direct oral anticoagulant within 48 hours (unless drug specific levels are normal), heparin with raised activated partial thromboplastin time, uncontrolled blood pressure, suspected aortic dissection, infective endocarditis, intracranial tumour or aneurysm, and extensive hypodensity on CT.
• Blood pressure under 185/110 mmHg before treatment and under 180/105 mmHg for 24 hours after; labetalol 10 to 20 mg IV over 1 to 2 minutes, repeated once, or an infusion; avoid in asthma, heart block and bradycardia.
• No antiplatelet or anticoagulant for 24 hours after thrombolysis, with repeat imaging before they start.
• Mechanical thrombectomy for proximal anterior circulation large vessel occlusion (internal carotid, M1, sometimes M2) within 6 hours, and up to 24 hours when imaging shows salvageable tissue, with consideration for basilar artery occlusion. Immediate referral to a thrombectomy capable centre.
• Aspirin 300 mg orally (or rectally or by nasogastric tube) daily for 14 days when thrombolysis is not given and haemorrhage is excluded, then long term single antiplatelet therapy (clopidogrel 75 mg daily preferred, or aspirin 75 mg daily with a proton pump inhibitor in selected patients).
• Minor non-cardioembolic stroke or high risk transient ischaemic attack (ABCD2 score of 4 or more, or high risk imaging features, NIHSS 3 or less): aspirin 300 mg plus clopidogrel 300 mg loading dose within 24 hours, then clopidogrel 75 mg and aspirin 75 mg daily for 21 days, then single antiplatelet therapy.
• Atrial fibrillation: anticoagulation with a direct oral anticoagulant (apixaban 5 mg twice daily; reduce to 2.5 mg twice daily if two of age 80 or more, weight 60 kg or less, creatinine 133 micromol/L or more), started 2 to 4 days after mild to moderate stroke and about 6 to 8 days after large infarcts, with timing adjusted to infarct size and imaging.
• Atorvastatin 80 mg orally at night, with a later target LDL cholesterol under 1.8 mmol/L, increased intensity as needed.
• Blood pressure: start or adjust antihypertensives after the first 24 to 72 hours; long term target under 130/80 mmHg.
• Symptomatic carotid stenosis of 50 to 99 percent (NASCET method), ideally 70 to 99 percent: carotid endarterectomy within 2 weeks of the event.
• Early swallow assessment, enteral feeding if unsafe, prevention of venous thromboembolism with intermittent pneumatic compression (add enoxaparin 40 mg subcutaneously daily when immobile and no haemorrhage), early mobilisation after 24 hours, stroke unit care, and rehabilitation.

Intracerebral haemorrhage

• Systolic blood pressure target 130 to 150 mmHg within 1 hour of treatment, avoiding falls under 130 mmHg; labetalol 10 to 20 mg IV or glyceryl trinitrate infusion.
• Anticoagulant reversal: warfarin with vitamin K 5 to 10 mg IV and prothrombin complex concentrate 25 to 50 IU/kg adjusted to the international normalised ratio and product label; dabigatran with idarucizumab 5 g IV; apixaban or rivaroxaban with andexanet alfa or prothrombin complex concentrate dosed as the product label states; heparin with protamine 1 mg for each 100 units given in the last 2 to 3 hours (maximum 50 mg).
• Neurosurgical referral for cerebellar haemorrhage over 3 cm, hydrocephalus, or brainstem compression, and for selected supratentorial lesions.
• Platelet transfusion only for thrombocytopenia (not for antiplatelet associated haemorrhage).

Other causes

• Cerebral venous sinus thrombosis: enoxaparin 1 mg/kg subcutaneously every 12 hours (adjust when creatinine clearance is under 30 mL/min), even with haemorrhagic infarction, then oral anticoagulation for 3 to 12 months.
• Space occupying lesion with vasogenic oedema: dexamethasone 10 mg IV, then 4 mg every 6 hours, with gastric protection and glucose monitoring; neurosurgical and oncology referral.
• Brain abscess: neurosurgical referral and ceftriaxone 2 g IV every 12 hours plus metronidazole 500 mg IV every 8 hours, with vancomycin added when staphylococcal or resistant organisms are possible.
• Bacterial meningitis or encephalitis: ceftriaxone 2 g IV every 12 hours with dexamethasone 10 mg IV every 6 hours for 4 days (first dose before or with the antibiotic), ampicillin 2 g IV every 4 hours if over age 60 or immunocompromised, and aciclovir 10 mg/kg IV every 8 hours for suspected encephalitis (adjust in renal impairment).
• Multiple sclerosis relapse or acute demyelination: methylprednisolone 1 g IV daily for 3 to 5 days, with gastric protection and glucose monitoring.
• Spinal cord compression: dexamethasone 16 mg orally or IV daily (or 10 mg IV then 4 mg every 6 hours) while arranging emergency MRI and neurosurgical or oncology referral.
• Todd paresis: observe, with resolution usually within 24 to 48 hours; treat the seizure cause.
• Hemiplegic migraine and functional weakness: diagnosis after exclusion of stroke, with specialist management.

Monitoring. Neurological observations and NIHSS at baseline, 1, 6 and 24 hours; blood pressure, glucose, temperature and oxygen saturation; swallow; signs of haemorrhagic transformation or oedema; bladder and bowel function; mood.

Referral and escalation. Immediate stroke team and thrombectomy centre referral for any suspected acute stroke within 24 hours. Neurosurgery for haemorrhage, hydrocephalus or space occupying lesion. Vascular surgery for symptomatic carotid disease. Cardiology for cardioembolic sources. Neurology for demyelination and inflammatory disease.

Admission criteria. All acute focal weakness, including transient ischaemic attack with high risk features; low risk transient ischaemic attack needs specialist review within 24 hours and can be managed as an outpatient.

Discharge and safety netting. Return immediately for new or worsening weakness, speech or visual loss, severe headache, drowsiness or seizure. Advise on driving restrictions, secondary prevention, smoking cessation and rehabilitation access.