ABPMR Neuromuscular Medicine flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Amyotrophic lateral sclerosis diagnosis

Defined by upper and lower motor neuron findings in at least two body regions with progressive spread, absent sensory loss, and electromyographic active plus chronic denervation in multiple myotomes.

Spinal muscular atrophy genetics

Caused by homozygous deletion of SMN1; SMN2 copy number modulates severity, so type 1 usually carries two copies and type 3 carries three or more.

Kennedy disease

X-linked spinobulbar muscular atrophy from an expanded CAG repeat in the androgen receptor gene; causes bulbar and limb weakness, gynecomastia, and mild sensory neuropathy.

Syringomyelia

Central cord cavity producing cape-like suspended loss of pain and temperature, lower motor neuron signs at the level, and spasticity below; often associated with Chiari I malformation.

Brown-Séquard syndrome

Hemisection of the cord causing ipsilateral weakness and loss of proprioception with contralateral loss of pain and temperature beginning one to two segments below the lesion.

Parsonage-Turner syndrome

Neuralgic amyotrophy presenting with abrupt severe shoulder pain followed by patchy asymmetric weakness; long thoracic, suprascapular, and anterior interosseous nerves are commonly involved.

Root avulsion electrodiagnosis

Preganglionic avulsion preserves sensory nerve action potentials because the dorsal root ganglion remains intact, while needle electromyography shows dense denervation in the corresponding myotomes.

Erb versus Klumpke palsy

Upper trunk C5-C6 injury (Erb) weakens shoulder abduction and elbow flexion; lower trunk C8-T1 injury (Klumpke) weakens hand muscles and may cause Horner syndrome.

Diabetic lumbosacral radiculoplexus neuropathy

Asymmetric painful thigh and pelvic girdle weakness in diabetes; electromyography shows axonal loss across multiple lumbosacral roots and plexus branches, and weight loss is common.

Pancoast tumor syndrome

Apical lung tumor infiltrating the lower brachial plexus, producing hand weakness, medial forearm sensory loss, and Horner syndrome from sympathetic chain involvement.

Charcot-Marie-Tooth type 1

Demyelinating hereditary neuropathy with uniformly slowed conduction velocities, typically below 38 m/s in upper limb nerves, often from PMP22 duplication on chromosome 17.

HNPP genetics

Hereditary neuropathy with liability to pressure palsies results from PMP22 deletion and shows mild generalized slowing plus focal conduction slowing at common entrapment sites.

Guillain-Barré cerebrospinal fluid

Albuminocytologic dissociation means elevated cerebrospinal fluid protein without pleocytosis, typically appearing in the second week of illness and supporting the diagnosis.

Vasculitic neuropathy

Painful, asymmetric, stepwise sensorimotor axonal neuropathy from nerve ischemia; nerve biopsy shows transmural inflammation and axonal degeneration, and treatment is immunosuppression.

Ulnar neuropathy at elbow

Demonstrated by slowed conduction velocity or conduction block across the elbow segment, with a preserved dorsal ulnar cutaneous sensory response distinguishing it from a lower lesion.

Carpal tunnel syndrome criteria

Median sensory distal latency prolonged relative to the ulnar or radial response, or prolonged median motor distal latency with reduced amplitude; thenar wasting indicates axonal loss.

Repetitive nerve stimulation decrement

A greater than 10 percent decline in compound muscle action potential amplitude between the first and fourth responses at 2-3 Hz stimulation, indicating postsynaptic neuromuscular junction failure.

Single-fiber electromyography

Measures jitter, the variability of interpotential intervals between two muscle fibers of the same motor unit; increased jitter and blocking are the most sensitive findings in myasthenia gravis.

Lambert-Eaton facilitation

Brief exercise or high-frequency stimulation produces a marked increment in compound muscle action potential amplitude, often over 100 percent, because presynaptic calcium influx is enhanced.

Anti-MuSK myasthenia gravis

Subtype with prominent bulbar, facial, and respiratory weakness, frequent muscle atrophy, poor response to thymectomy, and variable response to cholinesterase inhibitors.

Botulism electrodiagnosis

Presynaptic blockade with low baseline compound muscle action potential amplitudes, an incremental response to high-frequency stimulation, and descending flaccid weakness with pupillary dilation.

Thymoma in myasthenia gravis

Present in about 10 to 15 percent of patients with myasthenia gravis; all patients need chest imaging, and thymectomy is indicated for thymoma regardless of antibody status.

Dermatomyositis pathology

Perifascicular atrophy with perivascular inflammatory infiltrates and complement deposition on capillaries; clinically features heliotrope rash, Gottron papules, and proximal weakness.

Inclusion body myositis

Treatment-resistant myopathy after age 50 with asymmetric finger flexor and quadriceps weakness, rimmed vacuoles on biopsy, and mixed myopathic and neurogenic electromyographic changes.

Myotonic dystrophy type 1

CTG repeat expansion in DMPK causing distal and facial weakness, grip and percussion myotonia, cataracts, cardiac conduction defects, and insulin resistance; electromyography shows dive-bomber discharges.

Myopathic electromyography

Short-duration, low-amplitude, polyphasic motor unit potentials with early or full recruitment at low effort; fibrillation potentials may appear in inflammatory and necrotizing myopathies.

McArdle disease

Myophosphorylase deficiency causing exercise-induced cramps, myoglobinuria, and a second-wind phenomenon; forearm ischemic exercise raises ammonia but not lactate.

H reflex

Monosynaptic reflex elicited by submaximal tibial nerve stimulation and recorded from the soleus; useful for studying the S1 root and the proximal tibial nerve.

F wave

Late response from antidromic activation of anterior horn cells that assesses proximal motor nerve segments; absent or prolonged F waves suggest demyelinating neuropathy or radiculopathy.

Fibrillation potential timing

Spontaneous single-fiber discharges appear about two to three weeks after acute nerve injury and indicate active denervation of individual muscle fibers.

Conduction block

A decline in compound muscle action potential amplitude or area across a nerve segment beyond that expected from temporal dispersion, indicating focal demyelination with preserved distal axons.

Myokymic discharges

Grouped, rhythmic motor unit discharges firing at roughly 5 to 60 Hz; they suggest demyelination, radiation plexopathy, brainstem lesions, or Guillain-Barré syndrome.