PNS And Skeletal M Flashcards
Neuromuscular diseases are a group of disorders that typically present with what?
Weaknes, muscle pain and sensory deficits
What information do thin unmyelinated fibers convey?
Autonomic functions, pain and temp; slowest conduction speeds due to lack of myelin and small diameter
What information do large diameter axons with thick myelin sheaths convey?
Light touch and motor signals; fast conduction speed
How do pts with peripheral neuropathy generally describe their pain?
As tingling, stabbing, burning or “pins and needles”
What is Bell’s palsy?
A mononeuropathy affecting CN VII —> facial muscle paralysis; occurs between 15-60 yo and generally resolves spontaenously
What are the sx of Bell’s palsy?
One sided facial droop within 48-72 hours of initial sx; assoc with URI and DM; facial tingling, mid severe HA/neck pain, memory problems, balance issues, ipsilateral limb paresthesias, ipsilateral limb weakness and sense of clumsiness
What are other examples of infectious polyneurpathies?
Lyme dz and HIV
What is lyme dz polyneuropathy?
Second and 3rd stages of dz; polyradiculoneuropathy; unilateral or bilateral facial N palsies
What is HIV polyneuropathy?
Early stage HIV infection; mononeuritis multiplex, demyelinating DO that resembles Guillain-Barre, chronic inflammatory demyelinating polyradiculoneuropathy; later stages assoc with distal sensory neuropathy
Disorders that impair function of the NMJ tend to present with what?
Painless weakness and fatigue
What is the development of skeletal M?
During embryogenesis skeletal M develops thru fusion of mononucleated precursor cells (myoblasts) into multinucleated myotubes; these matre into myofibers of varying length that contain 1000s of nuclei; in adults these myofibers are arranged in fascicles each associated with a small pool of stem cells (satellite cells) which can contribute to muscle regeneration following injury
What is juvenile dematomyositis?
Avg age of onset 7 yo; MC inflammatory myopathy in children; calcinosis and lipodystrophy; less likely to be associated with myositis specific Abs, cardiac involvement, ILD or an undelrying malignnacy
What is the first line tx for inflammatory myopathies?
Corticosteoids
If a pt has a steroid resisant inflammatory myopathy, what is used to tx their condition?
Immunosuppressive drugs or steroid sparing agents (azathioprine and MTX)
What is 3rd line tx for inflammatory myopathies?
IVIg, cyclophosphamide, cyclosporine and rituximab
Inclusion body myositis usually responds poorly to what?
Steroids or immunosuppressive tx
Which gene is associated with malignant hyperthermia?
RYR1 gene (ryanodine receptor); 19q13.2
When do congenital myopathies present?
In infancy with M defects that tend to be static or to improve over time; assoc with developmental abnormalities of the CNS as well as progressive M damage
What are muscular dystrophies?
Progressive muscle damage with sx presenting after infancy (between childhood and adulthood)
What are some congenital conditions with defects in ECM surrounding myofibers?
Ullrich congential muscular dsytrophy (UCMD) which leads to hypotonia, proximal contractures and distal hyperextensibility; Merosin deficiency
What are some congential conditions with abnormalities in receptors for ECM?
Congenital muscular dystrophy as well as developmental defects of the CNS and eyes that cause seizures, intellectual disability and blindness
Which proteins are involved in limb girdle muscular dystrophy?
Sarcoglyan complex of proteins
What are the two general patterns of muscle dysfunction seen in diseases of lipid or glycogen metabolism?
Sx with exervise or fasting (severe muscle cramping and pain or extensive muscle necrosis aka rhabdomyolysis) + slowly progressive muscle damage wihtout episodic manifestations
What is spinal muscular atrophy?
Neuropathic disorder, loss of neurons —> muscle weakness and atrophy
