Neuromuscular Flashcards
What is the inheritance and gene defect of hypokalemic periodic paralysis?
Autosomal Dominant but may have sporadic cases;
2 types of mutation
Type 1: Calcium channel gene CACNA1S on Chromosome 1q31)
Type 2: Sodium channel gene SCN4A
What are the Creatinine Kinase Level in Steroid-Induced Myopathy and EMG findings?
serum CK normal
EMG are nonspecific
What is the histopath findings in Steroid Myopathy?
atrophy of type II fibers
Patient presents with hypotonia and weakness at birth with ptosis and ocular palsies. There is involvement of facial, pharyngeal, laryngeal and neck muscle weakness. Diagnosis?
Centronuclear Myopathy
What is the histologic findings in muscle biopsy of centronuclear myopathy?
small muscle fibers and central nucleation, as well as predominance of type I fibers, which are small and hypotrophic
Age of onset of myasthenia gravis
bimodal for both men and women:
Women (20-24yrs old and 70-75yrs old)
Men (30-34yrs old and 70-74yrs old)
Female > Male (7:3)
What is the most common type of Myasthenia Gravis?
Ocular MG most common (ptosis and diplopia)
What is the pathophysiology of MG in its most common form?
Autoimmune due to antibodies against the acetylcholine receptor
What is the finding of Tensilon Test in MG? What is the function of Edrophonium?
administration of edrophonium leads to transient improvement of weakness within minutes of administration. Edrophonium is an IV acetylcholinesterase inhibitor
What is the EMG and RNS finding in Myasthenia Gravis?
EMG: electrodecremental response and increase jitter
RNS: presence of a 10% or greater decrement in amplitude of a CMAP between the first and fourth to fifth stimuli (suggest NMJ Disorder)
What is the most sensitive test form MG?
Single-fiber EMG is the most sensitive test of NMJ transmission
How to differenitiate Dystrophic Myotonia Type 1 from Type 2
Type 1 (Distal) vs Type 2 (proximal) Cardiac and cataracts more common in DM Type 1
What is the histologic finding of Dystrophic Myotonia?
muscle fiber size variability, many fibers with multiple (5 to 10 or more) internalized nuclei, and atrophic fibers with nuclear clumps
What is the mutation in Dystrophic Myotonia Type II?
CCTG repeat expansion in an intron of the zinc finger protein 9 gene on chromosome 3q
associated with intranuclear accumulation of the expanded RNA transcripts
What is the gene involved in Fukuyama CMD?
Fukutin gene on Chromosome 9q
What is the histopathologic finding of Fukuya CMD?
dystrophic changes and reduced α-dystroglycan
20/Female presenting with slowly progressive weakness affecting shoulder, asymmetric present with difficulty lifting their arms above their head, with prominent involvement of the upper arms (scapular muscles, biceps, triceps, trapezius, serratus anterior, and pectoralis), with relative sparing of the deltoids. The upper arm seems to be more atrophic than the forearms, making the bones of the shoulder appear prominent. Facial weakness is evident, with weakness of the orbicularis oculi, zygomaticus, and orbicularis oris. Diagnosis and Defect?
facioscapulohumeral muscular dystrophy (FSHD)
Autosomal Dominan
D4Z4 located on chromosome 4q35
late-onset muscular dystrophy with manifestations restricted to the ocular and pharyngeal regions. Frequent in French-Canadian Descent. Diagnosis and defect?
oculopharyngeal muscular dystrophy
autosomal dominant
GCG repeat expansion in the poly-A–binding protein 2 gene on chromosome 14q11