Treat yoself
What are 3 ways PT can help patients with nerve injuries?
Limb care if sensory loss is present
Muscle activation via E-stim
Exercise to retain function and use of other muscles
ROM
Splints prescribed for normal positioning of limb
How do the EMG findings for amplitude and duration of MUAPs differ for neurogenic vs. myopathic lesions?
Neurogenic- large amplitude, long duration
Myopathic- small amplitude, short duration
What peripheral nerve innervates the hamstrings?
Sciatic nerve
What is the most common LE nerve injury, and name 2 mechanisms/activities that can increase your risk for it.
Sciatica-- lifting a heavy weight, doing manual labor, etc.
What is the hallmark sign of MG?
Specific muscle fatigability
Name 3 different surgical options for nerve injuries, and identify which of the 3 is typically the preferred surgical approach.
Nerve repair (to suture epi/perineurium), nerve graft/transfer, tendon transfer
Nerve graft = preferred
On an EMG, demyelination is indicated by ________, while axonal loss is indicated by __________.
slowed NCV; smaller amplitude CMAP
This syndrome is caused by compression of the deep peroneal nerve under the extensor retinaculum.
Anterior tarsal tunnel syndrome
What is a "scotty dog sign", and which spinal conditions do we see this with?
Elongation/break in the pars interarticularis-- seen with spondylolysis and spondylolisthesis
What organ is implicated in MG? And what is the name of the mechanism responsible for the abnormal body response?
Thymus gland, molecular mimicry
What is a good donor tendon used to improve foot drop?
Tibialis posterior is moved anterior to ankle, to help with DF
What may cause "spontaneous activity" on EMG?
Increased Ach in the denervated muscle
Peroneal neuropathy can cause sensory loss along which part(s) of the LE?
Anterolateral aspect of leg and dorsum of foot
The sciatic nerve encompasses which spinal segments?
L4-S3
What are 2 known viruses that can be a trigger for this autoimmune disorder?
Herpes simplex virus (HSV), and COVID-19
Name 2 options for a tendon transfer hoping to improve wrist drop and lack of thumb extension
Pronator teres to ECRB
Palmaris longus to EPL
What does myotonic discharge on EMG sound like?
revving engine
This disorder is characterized by compression in the tarsal tunnel below the flexor retinaculum. Name the disorder, and 3 muscles it affects.
Tibial nerve palsy/tarsal tunnel syndrome; FDL, FHL, tibialis posterior
Name 3 s/s of sciatica.
Leg muscle weakness, intermittent neurogenic claudication, positive SLR, calf pain that's relieved by spinal flexion, pain in low back and entire leg (except medial side) along sciatic nerve distribution
What are the 3 medical/diagnostic tests for MG? Describe any 1 of your choosing.
(1) Tensilon Test: IV dose of meds that delay removal of Ach from NMJ; obvious recovery in ocular weakness noted
(2) Ach Receptor (AChR) serum antibody testing: blood test in which 85% of MG pts test positive; other antibodies like LRP4 and MuSK may be present
(3) Needle EMG: repeated nerve stimulation leads to obvious decrease in amplitude of the CMAP in hand or arm muscles
Bonus Q (100 points): By the 4th or 5th nerve stimulus, what % decrease in CMAP amplitude will we see compared to the initial stimulation?
Describe the purpose of a nerve graft, and identify the most common nerve used for it.
Nerve grafts provide a channel for growth if the distal endoneurium is intact. Scar tissue is also removed.
Sural nerve is most common used
How do EMG findings for recruitment for a minimal effort contraction differ for a neurogenic vs. myopathic lesion?
Neurogenic-- reduced recruitment/firing rate
Myopathic-- increased early recruitment
What are the spinal segments for the following nerves? Superficial peroneal n., deep peroneal n., tibial n.
Superficial peroneal nerve: L4-S1
Deep peroneal nerve: L5-S2
Tibial nerve: L4-S3
Identify the L1-S2 dermatomes by pointing to your own body.
L1: inguinal ligament
L2: anterior proximal thigh
L3: anterior distal thigh, medial knee
L4: medial lower leg
L5: lateral lower leg, dorsum of foot
S1: lateral foot, heel
S2: poplitty fossa (posterior knee)
What is the pathophysiology of MG, and how does it differ from Eaton-Lambert Syndrome and Botulism?
Circulating antibodies block Ach receptors at post-synaptic NMJ, inhibiting stimulant effects of Ach.
In Eaton-Lambert Syndrome, blocking of calcium channels prevents release of Ach (abnormal presynaptic process).
In Botulism, clostridium botulinum bacteria block the snare proteins in vesicles that help release Ach in the synaptic cleft.