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
What is the mode of inheritance of LGMD-Type 1?
Autosomal Dominant
What is the mode of inheritance of LGMD-Type 2?
Autosomal Recessive
What is the mode of inheritance of Myotonic Dystrophy Type 1?
Autosomal Dominant
What is the mode of inheritance of Myotonic Dystrophy Type 2?
Autosomal Dominant
What is the mode of inheritance of Duchenne Muscular Dystrophy and Becker Muscular Dystrophy?
X-linked recessive
What is the gene and protein involved in Duchenne muscular dystrophy?
DMD- absence of Dystrophin
What is the mode of inheritance of paramyotonia congenita and gene involved?
autosomal dominant channelopathy caused by a mutation in the sodium channel gene SCN4A
What is the hisopathologic finding in Duchene Muscular Dystrophy?
showing endomysial fibrosis, loss of muscle fibers with residual fibers of different sizes, some of which are very large and eosinophilic, and others very small and atrophic
What is the mode of inheritance of central core myopathy and gene involved?
autosomal dominant disease
mutation in the ryanodine receptor gene RYR1 on chromosome 19q13.1
What are the antibodies involved in autoimmune myasthenia gravis?
Acetylcholine receptor modulating antibodies
Anti-striational muscle antibodies
anti–muscle-specific tyrosine kinase (MuSK) antibodies
What is the antibody involved in Lambert–Eaton syndrome?
Antibodies against presynaptic P/Q-type voltage-gated calcium channel
What is the antibody involved in polymyositis?
Anti-Jo 1 antibodies
What are the histopathologic findings in dermatomyositis?
atrophic fibers in the borders of the fascicles, which is known as perifascicular atrophy.
What are the histopathologic findings in polymyositis?
inflammatory infiltrate composed of lymphocytes and macrophages surrounding muscle fibers (endomysial infiltrates)
-Presence of regeneration and necrotic areas
What are the histopathologic findings in inclusion body myositis?
- endomysial inflammation,
- groups of atrophic fibers
- intracytoplasmic vacuoles with granular material known as rimmed vacuoles
What is the gene involved in LGMD-1A?
Myotilin
What is the gene involved in LGMD-2A?
Calpain-3
What is the gene involved in LGMD-1B?
Laminin A/C
What is the gene involved in LGMD-2B?
Dysferlin
What is the gene involved in LGMD-2I?
Fukutin
What is the gene involved in LGMD-2C-2F?
Sacroglycans
What is the gene involved in LGMD-2K?
POMT-1
What is the gene involved in Emery-Drefuss syndrome and gene involved?
Autosomal Dominant- Laminin A/C
X-linked- Emerin
What is the gene involved in Central Core Myopathy?
RYR1 (Ryanodine Receptor)
What is the histopathologic finding of central core myopathy?
Central pale cores in NADH stain from absence of mitochondria
Which of the following does not present with Arthrogryposis?
A. Werdnig-Hoffmann Motor Neuron Disease
B. Angelman Syndrome
C. Prader-Willi Syndrome
D. Neonatal Neuropathy
Angelman Syndrome
Patient with muscular weakness. Inquired if he needed to be evaluated for cardiac status.
What are the neuromuscular weakness that need to be evaluated?
M3EL
Myotonic Dystrophy Myofibrillar Myopathies Mitochondrial Disorders Emery-Dreifuss Dystrophy Limb Girdle Type 1B
