ABPN Neurology cheat sheet

Lateral corticospinal tract fibers decussate at the medullary pyramids; a lesion above the decussation causes contralateral spastic weakness, while anterior corticospinal fibers decussate segmentally.

Dorsal column fibers carry vibration and proprioception, synapse in nucleus gracilis and cuneatus, and cross as internal arcuate fibers to form the medial lemniscus.

Spinothalamic fibers cross one to two segments above entry in the anterior white commissure; a central cord lesion produces suspended cape-like loss of pain and temperature.

Posterior communicating artery aneurysm compresses CN III and causes a painful pupil-involving third nerve palsy; microvascular ischemia typically spares the pupil.

Lateral medullary (Wallenberg) syndrome: ipsilateral facial pain and temperature loss, Horner syndrome, ataxia, dysphagia, and contralateral body pain and temperature loss.

Broca aphasia: nonfluent speech with preserved comprehension from dominant inferior frontal gyrus damage; Wernicke aphasia: fluent speech with poor comprehension from dominant superior temporal damage.

Direct basal ganglia pathway (D1) inhibits GPi/SNr and facilitates movement; indirect pathway (D2) increases GPi/SNr inhibition and suppresses movement.

Motor homunculus: leg on medial cortex supplied by ACA, face and hand laterally supplied by MCA; occipital cortex is PCA territory.

Cerebellar hemispheric lesions cause ipsilateral limb ataxia; vermian lesions cause truncal and gait ataxia.

Alzheimer disease: early episodic memory loss, medial temporal and parietal atrophy, amyloid plaques, and tau neurofibrillary tangles; acetylcholinesterase inhibitors or memantine are symptomatic.

Behavioral variant frontotemporal dementia: disinhibition, apathy, loss of empathy, hyperorality, and executive deficits with frontal and anterior temporal atrophy; memory is relatively spared early.

Dementia with Lewy bodies: fluctuating cognition, visual hallucinations, parkinsonism, REM sleep behavior disorder, and neuroleptic sensitivity; occipital hypometabolism on FDG-PET.

Vascular dementia: stepwise decline with executive dysfunction, gait disturbance, urinary symptoms, and focal signs; subcortical white matter hyperintensities are common.

Primary progressive aphasia variants: semantic variant with temporal pole atrophy and anomia; logopenic variant with impaired repetition and phonological loop deficits.

Delirium: acute fluctuating attention and disorientation, often from drugs, infection, or metabolic derangement; dementia has insidious progressive decline with preserved attention until late.

Creutzfeldt-Jakob disease: rapidly progressive dementia, myoclonus, startle, and periodic sharp wave complexes; RT-QuIC and 14-3-3 support diagnosis.

Normal pressure hydrocephalus: gait apraxia, urinary incontinence, and dementia, with ventriculomegaly and a positive large-volume lumbar puncture tap test.

Gerstmann syndrome: acalculia, agraphia, finger agnosia, and right-left disorientation from dominant inferior parietal lobe damage.

Intravenous alteplase is indicated within 4.5 hours of ischemic stroke onset when blood pressure is below 185/110 mm Hg and there is no hemorrhage on CT.

Mechanical thrombectomy is standard for large vessel occlusion up to 6 hours and selected patients up to 24 hours using DAWN or DEFUSE-3 imaging criteria.

TOAST stroke subtypes: large artery atherosclerosis, cardioembolism, small vessel occlusion, other determined cause, and undetermined cause.

Lacunar syndromes: pure motor (posterior limb internal capsule), pure sensory (thalamus), sensorimotor, ataxic hemiparesis, and dysarthria-clumsy hand.

ACA infarction: contralateral leg greater than arm weakness, abulia, and incontinence; MCA infarction: face and arm greater than leg weakness, aphasia or neglect.

Cerebellar hemorrhage larger than 3 cm or causing brainstem compression warrants surgical evacuation; malignant MCA infarction may require decompressive hemicraniectomy within 48 hours.

Subarachnoid hemorrhage: thunderclap headache, CT sensitivity highest within 6 hours, xanthochromia on lumbar puncture; nimodipine reduces delayed cerebral ischemia.

Cerebral venous thrombosis presents with headache, seizures, and hemorrhagic infarction; anticoagulation is given even in the presence of hemorrhagic transformation.

Basilar artery occlusion causes fluctuating consciousness, quadriparesis, and cranial nerve palsies; early revascularization improves outcome.

Focal temporal lobe seizures: epigastric rising sensation, déjà vu, automatisms, and impaired awareness; EEG may show temporal spikes.

Childhood absence epilepsy: 3 Hz generalized spike-and-wave, brief staring without postictal confusion, provoked by hyperventilation; ethosuximide is first line.

Juvenile myoclonic epilepsy: morning myoclonic jerks, generalized tonic-clonic seizures, 4-6 Hz polyspike-wave; valproate is effective but teratogenic.

Status epilepticus: benzodiazepine first, then fosphenytoin, valproate, or levetiracetam; refractory cases require anesthetic infusion and continuous EEG.

Carbamazepine and oxcarbazepine can worsen absence and myoclonic seizures; valproate, levetiracetam, and lamotrigine are broader-spectrum options.

West syndrome: infantile spasms, hypsarrhythmia, and developmental regression; treat with ACTH or vigabatrin.

Lennox-Gastaut syndrome: multiple seizure types, slow spike-and-wave, drop attacks, and intellectual disability; broad-spectrum therapy is often required.

SUDEP risk is increased by uncontrolled generalized tonic-clonic seizures, nocturnal seizures, and young adult age; nocturnal supervision may reduce risk.

Migraine without aura: 4-72 hours, unilateral pulsating pain, nausea, photophobia, and phonophobia; aura typically lasts 5-60 minutes.

Cluster headache: 15-180 minutes of severe periorbital pain with ipsilateral autonomic signs and restlessness; high-flow oxygen and sumatriptan are acute treatments.

Trigeminal neuralgia: lancinating V2 or V3 pain triggered by touch; carbamazepine is first line, and MRI evaluates for vascular compression or multiple sclerosis.

Medication overuse headache: headache on 15 or more days per month with frequent acute medication use; withdrawal of the offending agent is required.

Headache red flags: thunderclap onset, fever with neck stiffness, papilledema, new onset after age 50, positional worsening, and focal neurologic deficit.

Idiopathic intracranial hypertension: obese young woman, papilledema, pulsatile tinnitus, and elevated opening pressure; acetazolamide and weight loss are treatments.

Giant cell arteritis: age over 50, jaw claudication, scalp tenderness, elevated ESR/CRP, and visual loss; give corticosteroids immediately and confirm with temporal artery biopsy.

Postherpetic neuralgia: gabapentin, pregabalin, tricyclic antidepressants, or lidocaine patch; opioids are not first line.

Pain transmission: A-delta fibers carry fast sharp pain, C fibers carry slow dull pain, and gate control theory predicts that nonpainful input can modulate pain.

Myasthenia gravis: fatigable ptosis and diplopia, bulbar weakness, acetylcholine receptor antibodies, decrement on repetitive nerve stimulation, and jitter on single-fiber EMG.

Lambert-Eaton myasthenic syndrome: proximal weakness, autonomic symptoms, reflexes that increase after exercise, voltage-gated calcium channel antibodies, and small cell lung cancer association.

Guillain-Barré syndrome: ascending areflexic weakness, albuminocytologic dissociation, nadir within 2-4 weeks, and treatment with IVIG or plasma exchange.

Chronic inflammatory demyelinating polyneuropathy: progressive or relapsing weakness over more than 8 weeks, sensory involvement, demyelinating EMG, and response to IVIG, steroids, or plasma exchange.

Amyotrophic lateral sclerosis: upper and lower motor neuron signs without sensory loss; riluzole and edaravone modestly slow progression.

Myotonic dystrophy type 1: CTG repeat expansion, distal weakness, myotonia, cataracts, and cardiac conduction disease; autosomal dominant with anticipation.

Duchenne muscular dystrophy: X-linked dystrophin deficiency, Gowers sign, calf pseudohypertrophy, elevated creatine kinase, and cardiomyopathy; corticosteroids slow decline.

Charcot-Marie-Tooth type 1A: demyelinating neuropathy from PMP22 duplication, pes cavus, hammer toes, and slow nerve conduction velocities.

Botulism: descending flaccid paralysis, autonomic dysfunction, and pupillary dilation from presynaptic acetylcholine release blockade.

Parkinson disease: asymmetric resting tremor, bradykinesia, rigidity, and postural instability; levodopa is the most effective symptomatic therapy.

Progressive supranuclear palsy: vertical supranuclear gaze palsy, early falls, axial rigidity, and midbrain atrophy with the hummingbird sign.

Multiple system atrophy: autonomic failure, cerebellar ataxia, and parkinsonism; MRI may show the hot cross bun sign in the pons.

Corticobasal syndrome: asymmetric apraxia, alien limb phenomenon, cortical sensory loss, and dystonia.

Huntington disease: CAG repeat expansion, chorea, psychiatric symptoms, dementia, and caudate atrophy; autosomal dominant with anticipation.

Essential tremor: bilateral action and postural tremor, alcohol responsiveness, and treatment with propranolol or primidone.

Tardive dyskinesia: involuntary oro-bucco-lingual movements after dopamine antagonist exposure; treat with VMAT2 inhibitors such as valbenazine or deutetrabenazine.

Wilson disease: low ceruloplasmin, elevated urinary copper, Kayser-Fleischer rings, liver disease, and psychiatric symptoms; chelation therapy is essential.

Restless legs syndrome: urge to move legs at rest, worse in evening, relieved by movement; iron deficiency should be evaluated.

Multiple sclerosis 2017 McDonald criteria require dissemination in space and time; typical MRI regions are periventricular, juxtacortical, infratentorial, and spinal cord.

Neuromyelitis optica spectrum disorder: AQP4-IgG, severe optic neuritis, longitudinally extensive transverse myelitis, and area postrema syndrome; complement inhibitors prevent relapse.

MOG antibody disease: optic neuritis, ADEM-like presentations, and transverse myelitis; MOG-IgG testing confirms.

ADEM: post-infectious encephalopathy with multifocal white matter lesions, often in children; corticosteroids are first-line treatment.

Herpes simplex encephalitis: fever, seizures, confusion, and temporal lobe involvement; CSF PCR and early intravenous acyclovir are standard.

Neurosyphilis: CSF VDRL, pleocytosis, and elevated protein; intravenous penicillin G is treatment.

Lyme neuroborreliosis: facial nerve palsy, radiculitis, and CSF pleocytosis; doxycycline or ceftriaxone is effective.

Progressive multifocal leukoencephalopathy: JC virus, progressive asymmetric white matter lesions without mass effect or enhancement; natalizumab and immunosuppression increase risk.

Anti-NMDA receptor encephalitis: young women, ovarian teratoma, psychiatric symptoms, seizures, dyskinesias, and hypoventilation; immunotherapy and tumor removal are indicated.

Glioblastoma: IDH-wildtype, ring-enhancing intra-axial mass with central necrosis and edema, often crossing the corpus callosum; temozolomide and radiation follow resection.

Meningioma: extra-axial, homogeneously enhancing mass with a dural tail; most are benign and observation or resection is based on symptoms and growth.

Pituitary adenoma: bitemporal hemianopia from optic chiasm compression; prolactinomas are treated with dopamine agonists.

Spinal cord compression: back pain, weakness, sensory level, and bowel or bladder dysfunction; urgent MRI and dexamethasone are indicated.

Papilledema: bilateral optic disc swelling from raised intracranial pressure, often with absent spontaneous venous pulsations and enlarged blind spots.

Optic neuritis: painful monocular vision loss, reduced color vision, relative afferent pupillary defect, and Uhthoff phenomenon; brain MRI predicts multiple sclerosis risk.

Nonarteritic anterior ischemic optic neuropathy: painless altitudinal visual loss with sectoral disc edema in older patients with vascular risk factors.

Vestibular schwannoma: unilateral sensorineural hearing loss and tinnitus; gadolinium MRI shows an enhancing internal auditory canal mass.

Benign paroxysmal positional vertigo: brief positional vertigo with upbeat torsional nystagmus on Dix-Hallpike; canalith repositioning is curative.

Simple febrile seizure: age 6 months to 5 years, generalized, under 15 minutes, no recurrence within 24 hours; daily antiepileptic therapy is not indicated.

Neonatal seizures: often subtle with apnea or autonomic changes; hypoglycemia and hypocalcemia must be checked, and phenobarbital is first line.

Cerebral palsy: nonprogressive motor impairment; spastic diplegia is associated with periventricular leukomalacia in preterm infants.

Fragile X syndrome: FMR1 CGG repeat expansion, macroorchidism, long face, autism, and intellectual disability.

Rett syndrome: MECP2 mutation in girls, developmental regression, hand-wringing stereotypies, and acquired microcephaly.

Tuberous sclerosis: TSC1 or TSC2 mutation, ash-leaf spots, facial angiofibromas, cortical tubers, subependymal giant cell astrocytoma, and infantile spasms.

Neurofibromatosis type 1: NF1 mutation, café-au-lait spots, axillary freckling, Lisch nodules, optic glioma, and pheochromocytoma.

Dravet syndrome: SCN1A mutation, prolonged febrile seizures, developmental regression, and temperature-sensitive seizures.

Chiari II malformation: myelomeningocele, hydrocephalus, and tectal plate beaking; associated with folate deficiency prevention.

Glasgow Coma Scale: eye 4, verbal 5, motor 6; scores 13-15 are mild, 9-12 moderate, and 3-8 severe traumatic brain injury.

Epidural hematoma: middle meningeal artery injury, biconvex shape on CT, temporal bone fracture, and a lucid interval.

Subdural hematoma: bridging vein tearing, crescent-shaped collection, elderly patients and anticoagulation are risk factors.

Diffuse axonal injury: gray-white junction, corpus callosum, and brainstem lesions; MRI susceptibility-weighted imaging is more sensitive than CT.

Cushing reflex: hypertension with bradycardia and irregular respiration indicates raised intracranial pressure and impending herniation.

Cerebral perfusion pressure equals mean arterial pressure minus intracranial pressure; target is typically 60-70 mm Hg after severe traumatic brain injury.

Neurogenic shock: hypotension and bradycardia from loss of sympathetic tone after cervical spinal cord injury; spinal shock is areflexia without hypotension.

Central cord syndrome: hyperextension injury with greater arm than leg weakness; surgical decompression is considered for persistent compression.

Wernicke encephalopathy: ophthalmoplegia, ataxia, and confusion from thiamine deficiency; give intravenous thiamine before glucose to prevent Korsakoff syndrome.

Vitamin B12 deficiency: subacute combined degeneration with dorsal column and corticospinal signs, paresthesias, and macrocytic anemia.

Hepatic encephalopathy: asterixis, confusion, and elevated ammonia; lactulose and rifaximin reduce ammonia production.

Carbon monoxide poisoning: bilateral globus pallidus lesions and cherry-red skin; treat with high-flow oxygen or hyperbaric oxygen.

Methanol poisoning: severe metabolic acidosis, visual loss, and putaminal necrosis; fomepizole or ethanol blocks metabolism.

Ethylene glycol poisoning: metabolic acidosis, oxalate crystals, and hypocalcemia; fomepizole is antidotal.

Organophosphate poisoning: SLUDGE and DUMBELS from acetylcholinesterase inhibition; atropine and pralidoxime are treatments.

Serotonin syndrome: hyperthermia, clonus, hyperreflexia, and agitation after serotonergic drugs; stop the agent and give cyproheptadine if severe.

Osmotic demyelination syndrome: rapid correction of hyponatremia causes pontine and extrapontine demyelination; correct sodium slowly.