Nerve and Muscle Flashcards
(42 cards)
Two tests for Myasthenia gravis:
Tensilon test: edrophonium, a readily reversible ACh esterase inhibitor, or the ice pack test, that can temporarily reverse ptosis.
Myasthenia gravis shows what on EMG?
Decremental response to repetitive stimulation.
What type of antibodies are found in MG?
Anti-ACh receptor, in about 80-90% of patients.
What is MG?
A neuromuscular junction disorder where antibodies block and distort the acetylcholine receptor.
Treatment for myasthenic crisis:
IVIG, plasmapharesis immediately to reduce antibody load in blood, however proactive intubation in an emergency.
What is Lambert-Eaton myasthenic syndrome?
a paraneoplastic disorder. It is characterized by slowly progressive weakness that, in contrast to myasthenia gravis, usually spares eye muscles, and there is a brief improvement in strength with exercise. This is seen on EMG as an incremental response to repetitive stimulation. The mechanism is by the production of antibodies against presynaptic calcium channels.
The tumor most likely to cause Lambert-Eaton myasthenic syndrome is:
Lungs (often small-cell).
Treatment for MG:
Maintenance with pyridostigmine (Mestinon), a reversible cholinesterase inhibitor, steroids (azathioprine) are also standard of care.
What is myasthenic crisis?
Patients will have respiratory insufficiency that is out of proportion to the rest of their muscle weakness or increased generalized weakness of their bulbar muscles necessitating intubation. This is a medical emergency. Patients must be admitted to the ICU and have their respiratory muscle strength monitored with serial FVC measurements.
LP results in GBS:
WBC normal, RBC normal, protein high: this pattern is referred to as albuminocytologic dissociation.
Which infectious agent commonly precedes GBS?
Campylobacter jejuni
Treatment for GBS:
IVIG (easier and less SE), plasmapharesis
Decreased conduction velocity and conduction block indicate a _____.
demyelinating process
What is GBS?
An autoimmune disorder, often following a GI illness, where patients developing ascending weakness with minimal sensory symptoms.
Symptoms develop over hours to days and patients may also have significant back pain due to inflammation of nerve roots.
Loss of reflexes is a key to clinical diagnosis.
Where to look for ulnar nerve symptoms or “claw hand.”
The course of the ulnar nerve around the posterior aspect of the medial epicondyle makes it susceptible to traumatic injury when patients strike the medial epicondyle of the humerus posteriorly, or inferiorly with the elbow flexed, compressing the nerve against the bone.
Drop wrist and numbness on the back of the hand is due to injury of which nerve?
Radial nerve
Injury of femoral nerve presents how?
Weakness of knee extension and hip flexion.
What is lateral femoral cutaneous nerve syndrome?
Meralgia paresthetica: compression of the nerve as it exits the inguinal ligament, presents with sensory symptoms on the lateral thigh and can be treated with weight loss and wearing looser clothes.
Which nerve, when injured, leads to foot drop?
The common peroneal nerve divides into the deep and superficial branches. The deep branch is responsible for foot drop. There is also numbness of the lateral calf and foot.
The tibial nerve is responsible for what?
Foot plantar flexion
The sciatic nerve does what in the leg?
hamstring muscles/knee flexion
C5 and C6 nerve roots mediate which reflexes?
Biceps and brachioradialis
C6 and C7 (mostly C7) mediate which reflex?
Triceps reflex
L3 and L4 (mostly L4) mediates which relfex?
Knee jerk
