Neuromuscular Jxn and Myopathy Flashcards
Baclofen
GABA 8 Receptor agonist
Anterior horn cells
Stimulated by Glutamate
Inhibited by GABA and Glycine
Glutamate is broken into GABA
By enzyme:
Glutamate Decorboxylase (GAD)
GAD65 Ab blocks this enzyme in stiff person syndrome
Tetanus
Blocks the release of presynaptic GABA and Glycine
NeuroMyotonia
Voltage gated K+ channel antibodies
Myokymia is charachteristic
(another pathognomonic Myokymia was XRT induced Plexopathy)
Pre-Synaptic Toxins
Magnesium/Mg: Blocks Ca++ Channels
Botulinum: Blocks Ach release
Lathrotoxin (Black Widow): Excessive release of Ach
Tick Paralysis: Blocks Ach realease
Scorpion Venoum: Causes Ach release
B-Bungarotoxin (Snake Venoum): Inhibits Ach release
Post Synaptic Toxins
Curare: Binds nicotinic Ach receptors
Organophosphatase Poisoning
inhibts acetylchilnestrase so there is too much Ach
Leading cause of death:
Bronchospasm and Bronchorrhea
DUMBELLSS:
Diarrhea, Urination, Miosis, Bradycardia, Bronchospasm, Emesis, Lacrimation, Lethargy, Salivation, Seizure
AntiCholinergic symptoms
Usually Drug side effect
(Reduced Ach)
Antihistamines, antipsychotics, antidepressants, antiparkinsonian drugs, Atropin, Benztropin, Scopolamine
Blurry vision, Hallucination/Delirum, Mydriasis, Ileus, Urinary retention, Flushing, Hyperthermia
Blind as a Bat, Mad as a Hatter, Red as a Beet, Hot as a Hade, Dry as a bone
Meds Absolutely Contraindicated in MG
D-Penicillamine
Curare
Botulinum Toxin
Interferon-alpha
Neomycine and Quinine are contraindicated.
Myopathies with Normal CK
Steroid Myopathy
Hyperthyroid Myopathy
Mitochondrial Myopathy
Chanelopathies
Myopathies with Markedly elevated CK
Dystrophionopathies
Myoshi distal myopathy
Rhabdo, malignant hyperthermia and NMS
Polymyositis
X-Linked Myopathies
Men only
Gower’s Maneuver when standing (may show video or pic)
Duchenne’s: Dystrophin is completely absent. Very severe disease. Death by late teens to 20 y.o
Becker’s: Dystrophin very reduced. Death by 30-60’s
Emery-Dreifuss: Emerin Deficiency. Joint contractures; mostly arms and shoulder. Elbow contracture is pathognomonic for ABPN.
Autosomal Dominant Muscular Dystrophies.
FSHD: face and winged scapula. Popeye appearance (Deltoid and Bicep spared). Big wide eyes, pouting mouth.
Oculopharyngeal muscular Dystrophy: French Canadian descent. Ptosis and Dysphagia. No other eye symptoms. If Ptosis and Diplopia think MG
Limb Girdle Muscular Dystrophy (LGMD):
LGMD type 1 is AD
LGMD type 2 is AR
Myotonic Dystrophy (DM1) Type 1: CTG repeat. Long face, Temporal wasting, frontal balding, Myotonia (grabs door handles and can’t let go. CARDIAC COMPLCATIONS
Autosomal Recessive MD’s
LGMD type 2: accounts for 60% of Distal Myopathies
MD2: much less common than MD1. Milder and no cardiac complications
Distal Myopathies
LGMD type 2
Myotonic muscular Dystrophy
Inclusion Body Myositis
Myotonia congenita
Chloride Channel disorder. Get stiff with sitting for a while (Rusted Tin man) Onset age 4-12 yo AD form is milder AR form is more severe
Pompe’s
Acid Maltase Deficiency
Glycogen storage disease
Mostly a child disoder but:
in Adult: SOB, Proximal Weakness, and Myotonic discharges in Paraspinal muscles (this is the giveaway)
It leads to respiratory failure in adults. It’s a Neurologic emergency.
TX: IV alpha-Glucosidase
Myotonia
Improves with Repetition/exercise
Para Myotonia Congenita
Face muscles; usually eyes
Myotonia worsens with repetition.
Video of patient closing her eyes and can not open anymore; it’s stuck
Worsens with Cold and Hyperkalemia
Imitermittent Myopathies
Familial Hyperkalemic Periodic Paralysis. AD. Na+ Channel
Familial Hypokalemic Periodic Paralysis. AD. Ca++ Channel
Myophosphorylase Deficiency (McArdle’s dz)
Carnitine Palmityl Transferase Deficiency
HyperK PP
AD
Ca++ channel
Children, paralysis minute to hours, Progression variable, Insulin Helps Treated HIGH Carb diet EMG=Myotonia
HypoK PP
AD
Na+ Channel
Adolescent, Paralysis hours to days Progressive weakness in adulthood Insuline Aggrevates Treated with LOW Carb diet EMG NO myotonia
MyoPhosphorylase Deficiency
McArdle’s disease
Weakness and pain with exercise (hits a wall/Barrier)
improve with rest
Gets a second wind
Carnitine Palmityl Transferase deficiency
Myoglobulinuria post exercise in fasting state
Young guy, may be army, forced march without breakfast has severe weakness and very high CK
May be also triggered with Cold and Meds (Advil, Diazepam, general anesthetics)
Ophthalmoplegic Myopathies
Kearns-Sayre Syndrome: Mitochondrial
Ophthalmoplegia; Hearing Loss
Characteristic feature: Retinits Pigmentosa and Heart Blocks
Progressive External Ophthalmoplegia: Mitochondrial Ophthalmoplegia Ptosis Hearing loss Similar to MG BUT NO Diplopia
Dermatomyositis
Painful, Rash, and Muscle weakness
(Rash on face, chest, hands, but Elbow knockles, knees are typical because not seen in Lupus)
EMG: small motor units
Can be a/w Breast Ca
Anti Jo-1 Ab: Indication of Interstitial lung dz
Dermatomyositis Histology
PeriFascicular atrophy/inflammation
CD4 predominant
Polymyositis Histology
Endomysial inflammation
CD8 predominant
Polymyositis
Painless muscle weakness
the more severe the pain, the less likely it is Polymyositis
Woman 40-60
may be a/w viral prodrome
Inclusion Body Myositis
Most common Myopathy in >50 yo
Distal muscle weakness and atrophy (Hands/feet)
NO FASICULATION, NO HYPERREFLEXIA (DDX with ALS due to the hand atrophy)
Rimmed Vacuoles and inclusion bodies on biopsy
