Anatomy
Name the structures that are in the carpal tunnel.
Four FDS tendons, one FPL tendon, Median nerve, Four FDP tendon
Is the NCS contraindicated in patients with implanted pacemakers and cardioverter defibrillators?
No
Describe 3 methods to decrease stimulus artifact
1) Place ground between stimulator and recording electrodes
2)Ensure stimulator is optimally directly over the nerve
3) Lower the stimulus intensity
4) Rotate the anode
5) Increase distance between stimulator and recording electrodes
6) Ensure stimulator and recording electrode cables do not overlap
A 3 month old infant developed new onset diffuse weakness and hypotonia with a weak cry. Her parent's report that this just started this morning. They report that she developed a cough last week so they tried some natural remedies last night with local honey in her formula. What are you concerned for and expect to see on NCS/EMG?
Infantile Botulism: no honey for children less than a year of age. Can diagnose with a stool antigen test
Reduced CMAP amplitude, preserved conduction velocities and SNAPs.
Fibrillation potentials and positive sharp waves would be present on EMG
Which type of spinal muscular atrophy (SMA) has the latest presentation?
Which type of SMA has the worst prognosis?
Loss of lower motor neurons with progressive muscle wasting
Type I (Werdnig Hoffman) - onset 0-6mo, "floppy baby", respiratory failure, most do not live past 2yo
Type II (Dubowitz) - onset 6-18 months, variable severity, dec life expectancy but can live to adult hood
Type III (Kugelberg-Welander) - onset >12 months, able to walk at some time, life expectancy generally unaffected
Type IV: adulthood (>30)
What muscles (must name all) does the AIN supply?
Flexor pollicis longus
Pronator Quadratus
Flexor digitorum profundus 1,2
Name two provocative tests for thoracic outlet syndrome
Roos test
Adsons test
______ discharges on EMG may be an important marker for radiation induced injury.
A 14 year old girl notices that she is getting tired earlier than her classmates in gym class. She also notices that her vision becomes blurrier during these episodes and can't seem to keep her eyes open. What is your leading diagnosis and what causes it?
Myasthenia Gravis- caused by autoimmune antibodies binding to postsynaptic acetylcholine channels
A 1 year old baby develops nausea and vomiting and fatigue after she and her family moved into their new house which is a "fixer upper". He was walking but now seems more clumsy than before. What are you concerned for and what would you see on NCS?
Lead polyneuropathy
NCS would show axonal degeneration with more motor involvement than sensory.
What makes up the quadrilateral space in the arm and what nerve exits from that space?
1) Humerus, teres minor, teres major and long head of triceps
2) Axillary
what is synkinesis?
Aberrant regeneration of axons with facial nerve injuries leading to reinnervation of inappropriate muscles. (ie: lip twitching when closing an eye)
During NCS/EMG study, stimulation of the median nerve while recording the APB results in no response, despite normal bulk and strength of the thenar eminence. EMG is normal. What should you consider?
Riche-Cannieu anastomosis
A 6 year old child has been complaining of a headache and now has new onset facial palsy after returning from a family camping trip in the West Virginia countryside. Parents report that they used bug spray and don't remember seeing a rash. What is most common pathogen?
Borrelia burgdorferi from a deer tick causing Lyme Disease.
A 38 year old male reports worsening weakness that he reports started when he was unable to get Christmas decorations out of the attic. He now reports weakness is getting worse and is having trouble swallowing and has a new rash. His lab findings show an elevated CK. What is your diagnosis and what would you see on EMG?
Dermatomyositis
EMG with complex repetitive discharges, fibs and sharp waves and low amplitude polyphasic short duration MUAPs
Name the contents of the tarsal tunnel (in order from anterior to posterior).
Tibialis Anterior
Flexor Digitorum Longus
Posterior tibial artery
Posterior tibial vein
Tibial nerve
Flexor hallucis Longus
Weakness from which muscle causes medial winging?
serratus anterior from long thoracic nerve injury
What electrodiagnostic finding helps differentiate critical illness myopathy from critical illness polynueropathy?
Normal Sensory Nerve Action Potential
A concerned parent brings in her 6 year old son because he doesn't walk or run like the other kids on his soccer team. He met his developmental milestones at the later end of normal. His mother also reports that he has recently been asking to be carried up to his bedroom because the stairs make him too tired. How would you diagnose this patient and if you did a NCS what would you see?
1. CK (>10,000)
2. Genetic Testing: looking for dystrophin deletion
3. Whole genome sequencing
4. Muscle Biopsy
5. EMG/NCS is rarely needed now: would show low amplitude, short duration polyphasic MUAPs with early recruitment. CRDs and spontaneous activity present due to membrane instability
An 18 year old college freshman presents to office with chronic history of having difficulty walking and climbing the stairs. She reports that this has been happening for a while but seems to have been more frequent since moving into her dorm. She reports that she usually feels better after the first 5 stairs and after walking for a little while. She does not have any weakness on exam but does have percussion myotonia. You order an EMG. What is your leading diagnosis and what do you expect to see?
Myotonia Congenita
Emg would show myotonia with warm up phenomenon. Myotonia is reduced after maximal contractions.
Name 7 entrapment sites in the upper extremities
Ligament of Struthers, Bicipital Aponeurosis, PT syndrome, AIN syndrome, CTS, Guyon's canal, Cubital tunnel, Aracade of struthers, Arcade of Frohse, Supinator syndrome, PIN syndrome, spiral groove
If a limb cannot be adequately warmed, what is the correction factor for conduction velocity and distal latency?
Conduction velocity: 1.5-2.5 m/s/C
Distal latency: 0.2 m/s/C
Normal Standard Adult Values for Nerve Conduction Studies are reached by what age?
Ages 3 to 5
A 5 year old kid was playing behind the barn on his grandparent's farm. After dinner, his mother then noticed that he started having tight muscles and difficulty breathing. His grandpa reports that he recently had to bury an old horse that had stopped eating and was stiff behind the barn. What are you concerned for and would see on EMG?
Tetanus
EMG would show sharp waves, fibs, and polyphasia in affected muscles
A family presents to your office and report that their 6 year old son is more sleepy in the day. He has always had "trouble with sharing" and often would grab onto an item and not let go. You notice on physical exam that the child has a tent shaped mouth and his mother has a long thin face. What is your leading diagnosis?
Myotonic muscular dystrophy with unstable CTG repeats. The number of repeats can increase each generation causing symptoms to become more severe and present earlier.