100+ Free ABPN Neuromuscular Medicine Practice Questions

Acquired Peripheral Neuropathies

Guillain-Barre syndrome (AIDP, AMAN, AMSAN, Miller Fisher with anti-GQ1b, Bickerstaff brainstem encephalitis) — albuminocytologic dissociation in CSF, IVIG 2 g/kg over 5 days or PLEX (steroids ineffective). CIDP — symmetric proximal+distal weakness >8 weeks, conduction block and temporal dispersion, IVIG/steroids/PLEX first-line. MMN with conduction block (anti-GM1, IVIG only — steroids worsen). Vasculitic neuropathy (mononeuritis multiplex, ANCA panel, biopsy axonal with epineurial vessel inflammation). Diabetic (DSPN, treatment-induced, autonomic, radiculoplexus/Bruns-Garland). Toxic (vincristine, cisplatin, paclitaxel, bortezomib; amiodarone; isoniazid; nitrous oxide). Paraneoplastic (anti-Hu small-cell lung — sensory neuronopathy).

Inherited Neuropathies & Hereditary Disorders

Charcot-Marie-Tooth — CMT1A (PMP22 duplication 17p11.2, demyelinating, most common), CMT1X (GJB1/connexin-32, X-linked, may have CNS findings), CMT2 (axonal, MFN2, NEFL), CMT4 (autosomal recessive demyelinating). HNPP (PMP22 deletion, sausage-like tomacula on biopsy). Hereditary sensory and autonomic neuropathies (HSAN). Familial amyloid polyneuropathy (TTR mutations — patisiran, inotersen, vutrisiran, tafamidis). Friedreich ataxia (frataxin, GAA repeat). Refsum disease (phytanic acid). Fabry disease (GLA, X-linked alpha-galactosidase A — small-fiber painful crises, agalsidase ERT).

Motor Neuron Diseases (ALS, SMA)

ALS — UMN + LMN signs, El Escorial/Awaji-Shima criteria, fasciculations, split-hand sign. Riluzole 50 mg BID prolongs survival ~3 months, edaravone (IV/PO antioxidant), tofersen (SOD1 antisense, FDA 2023). NIV when FVC <50% or symptomatic; PEG when dysphagia/weight loss >10%. Spinal muscular atrophy — SMN1 deletion (5q13) with SMN2 copy number modifying severity; types 0/1/2/3/4. Treatments: nusinersen (intrathecal antisense), onasemnogene abeparvovec (Zolgensma AAV9 gene therapy <2 years), risdiplam (oral SMN2 splice modifier). Kennedy disease (X-linked CAG repeat in androgen receptor — bulbar weakness, gynecomastia, perioral fasciculations). Post-polio syndrome. PLS, PMA.

Neuromuscular Junction Disorders (MG, LEMS)

Myasthenia gravis — fatigable weakness, ocular/bulbar/limb; AChR antibodies (~85% generalized), MuSK (~5%, bulbar/respiratory predominant, atrophy, no thymoma), LRP4, seronegative. RNS decrement >10% at 3 Hz; SFEMG most sensitive (jitter, blocking). Ice pack test for ptosis. CT chest for thymoma. Treatments — pyridostigmine, prednisone, azathioprine/MMF, IVIG/PLEX for crisis, rituximab (especially MuSK), thymectomy (MGTX trial — benefit in AChR+ generalized <65 y), efgartigimod/rozanolixizumab (FcRn), eculizumab/ravulizumab/zilucoplan (C5 inhibitors — meningococcal vaccine required). LEMS — proximal lower limb weakness, autonomic dysfunction, areflexia (post-exercise facilitation), P/Q-type VGCC antibodies, paraneoplastic SCLC (~50%), CT chest screening, treatment 3,4-DAP (amifampridine). Congenital myasthenic syndromes. Botulism — descending paralysis, RNS post-exercise increment >100%.

Inflammatory Myopathies

Dermatomyositis — proximal weakness + heliotrope rash, Gottron papules, shawl/V-sign; perifascicular atrophy with MAC deposition on capillaries; antibodies (anti-Mi-2 classic skin, anti-TIF1-gamma cancer-associated, anti-NXP2, anti-MDA5 amyopathic with rapidly progressive ILD/skin ulcers, anti-SAE). Polymyositis (rare, dx of exclusion) — endomysial CD8+ T-cell infiltrate, MHC-I upregulation. Antisynthetase syndrome (Jo-1, PL-7, PL-12 — myositis, ILD, mechanic hands, Raynaud, arthritis, fever). Immune-mediated necrotizing myopathy — anti-HMGCR (statin-associated, persists after statin withdrawal), anti-SRP (severe) — scattered necrotic fibers with minimal inflammation. Inclusion body myositis — finger flexor + quadriceps weakness >50 y, rimmed vacuoles, anti-cN1A, no immunotherapy response. Treatment — steroids, MTX/AZA/MMF, IVIG, rituximab.

Muscular Dystrophies

Dystrophinopathies — Duchenne (out-of-frame DMD deletions, Gower sign, calf pseudohypertrophy, wheelchair by ~12, dilated cardiomyopathy; deflazacort/prednisone, exon-skipping eteplirsen/golodirsen/casimersen/viltolarsen, gene therapy delandistrogene moxeparvovec 2023), Becker (in-frame, milder). Myotonic dystrophy DM1 (CTG repeat DMPK 19q13, distal weakness, frontal balding, cataracts, cardiac conduction block, insulin resistance, anticipation), DM2 (CCTG ZNF9/CNBP, proximal). FSHD (D4Z4 contraction 4q35 with permissive 4qA, scapular winging, asymmetric facial weakness). LGMD (multiple genes — LGMD2A calpain-3, 2B dysferlin/Miyoshi, 2I FKRP). Emery-Dreifuss (EMD/LMNA — early contractures + cardiac conduction). OPMD (PABPN1 GCN expansion — ptosis, dysphagia). Congenital muscular dystrophies (merosin, collagen VI/Ullrich-Bethlem).

Channelopathies & Metabolic Myopathies

Hypokalemic periodic paralysis (CACNA1S, SCN4A; episodic weakness with high-carb meals or rest after exercise, K+ low, treatment K+ + acetazolamide/dichlorphenamide). Hyperkalemic periodic paralysis (SCN4A; brief attacks, often with myotonia, treatment thiazide/acetazolamide). Andersen-Tawil syndrome (KCNJ2 — periodic paralysis + long QT + dysmorphic features). Paramyotonia congenita (SCN4A — cold/exercise-induced worsening — paradoxical myotonia). Myotonia congenita — Thomsen (AD, CLCN1) and Becker (AR, CLCN1, more severe with warm-up phenomenon). Malignant hyperthermia (RYR1 — halothane/succinylcholine triggers, dantrolene treatment). McArdle disease (myophosphorylase deficiency, type V GSD, second-wind phenomenon). Pompe (acid alpha-glucosidase deficiency, ERT alglucosidase alfa). CPT II deficiency, MADD, mitochondrial myopathies (CPEO, MELAS, MERRF).

Electrodiagnostic Medicine (NCS/EMG)

Nerve conduction studies — distal latency, amplitude, conduction velocity, F-wave, H-reflex. Demyelinating (slow CV <70% LLN, prolonged DL, conduction block, temporal dispersion, prolonged F-waves) vs axonal (low amplitude with relatively preserved CV). Needle EMG — insertional activity, spontaneous (fibrillations, positive sharp waves = denervation; fasciculations, myokymia, myotonic discharges, complex repetitive discharges, neuromyotonia), MUAP morphology (small/short polyphasic = myopathic; large/long polyphasic = chronic neurogenic), recruitment patterns (early in myopathy, reduced/decreased in neurogenic). Repetitive nerve stimulation — slow 3 Hz decrement >10% (MG), high-frequency 50 Hz or post-exercise increment >100% (LEMS, botulism). Single-fiber EMG — jitter and blocking (most sensitive for MG, ~99%). Localizing focal mononeuropathies (carpal tunnel — median at wrist, ulnar at elbow, peroneal at fibular head, radial in spiral groove).

Nerve & Muscle Biopsy

Sural nerve biopsy indications — suspected vasculitis, amyloidosis, sarcoidosis, hereditary (when genetics non-diagnostic), atypical CIDP. Findings — onion bulbs (CMT1, CIDP), epineurial vessel inflammation (vasculitis), Congo red apple-green birefringence (amyloid), tomacula/sausage swellings (HNPP). Muscle biopsy — vastus lateralis or biceps brachii; perifascicular atrophy (DM), endomysial CD8+ infiltrate (PM/IBM), rimmed vacuoles (IBM), necrosis with minimal inflammation (IMNM), ragged-red fibers and COX-negative fibers (mitochondrial), nemaline rods, central cores. Immunohistochemistry for dystrophin/sarcoglycans/dysferlin/merosin. Skin biopsy with PGP9.5 for intraepidermal nerve fiber density (small-fiber neuropathy diagnosis).

Autonomic Disorders & Plexopathies

Autonomic — pure autonomic failure, MSA (autonomic + parkinsonism/cerebellar), diabetic autonomic neuropathy, amyloid, Sjogren, paraneoplastic anti-ganglionic AChR. Tilt-table testing, QSART, valsalva. POTS — HR rise >30 bpm (>40 in <19 y) within 10 min standing without orthostatic hypotension; treatment volume, salt, compression, midodrine, fludrocortisone, propranolol/ivabradine. Small-fiber neuropathy — burning pain, normal NCS, abnormal IENFD on skin biopsy or QSART. Brachial plexopathy — Parsonage-Turner (idiopathic neuralgic amyotrophy — pain then weakness, often anterior interosseous nerve), traumatic, radiation-induced, neoplastic, thoracic outlet. Lumbosacral plexopathy — diabetic amyotrophy (Bruns-Garland), retroperitoneal hematoma. Radiculopathies — C5-T1 and L4-S1 dermatome/myotome patterns.

Treatment & Therapeutics

IVIG — 2 g/kg over 2-5 days for GBS/CIDP/MG/MMN/DM/IMNM; complications include aseptic meningitis, renal failure (sucrose-containing), thrombosis, anaphylaxis (IgA-deficient with anti-IgA), hemolysis. Plasmapheresis — 5 exchanges over 7-14 days for GBS/MG crisis/CIDP; needs central line, removes coagulation factors. Steroids — first-line for CIDP/MG/inflammatory myopathy; calcium/vit D, PJP prophylaxis, bone density monitoring. Steroid-sparing — azathioprine (TPMT testing before initiation), MMF, methotrexate, cyclosporine, tacrolimus. B-cell depletion — rituximab (MuSK MG, IMNM, refractory CIDP). Complement inhibitors — eculizumab, ravulizumab, zilucoplan (AChR+ generalized MG, meningococcal vaccination required). FcRn inhibitors — efgartigimod, rozanolixizumab. Gene therapies — onasemnogene abeparvovec (SMA), delandistrogene moxeparvovec (DMD), tofersen (SOD1 ALS), patisiran/inotersen/vutrisiran (hATTR amyloidosis).