Chapter 34 - Nerve Compression Syndromes Flashcards
(93 cards)
How is nerve conduction in the carpal tunnel reported?
Latency is reported in milliseconds (ms)
What is latency?
Latency is the time it takes for an electrical stimulus to travel along a nerve from the site of stimulation to a recording electrode in a target muscle
What is the normal value for motor latency in the carpal tunnel?
Less than 0.4ms
How is nerve conduction at the elbow reported?
Nerve conduction is reported as velocity in meters/sec
What is a clinically significant decrease in velocity at the elbow?
A decrease in velocity of 10m/s or more is considered clinically significant
What is the difference between the compressive neuropathies and peripheral neuropathies?
In peripheral (systemic) neuropathies the nerve conduction is decreased diffusely both proximally and distally in multiple nerves. In compressive neuropathies nerve conduction is decreased distal to the compression only
What are typical EMG findings for long-standing nerve compression and axonal damage?
EMG will demonstrate wide biphasic fibrillation potentials in the presence of long-standing nerve compression
What is double crush syndrome?
The double crush syndrome hypothesizes that a site of proximal nerve compression in a series with a site of distal compression results in the same clinical neuropathy, whereas independently, neither site of compression is severe enough to cause clinical neuropathy
What is the treatment of choice for a ulnar neuroma in continuity with intact motor function?
The current optimal therapy involves micro-dissection of the neuroma using electrostimulation to identify and preserve motor fascicles. En bloc resection of the neuroma is inappropriate, as this would sacrifice nerve fascicles.
What are some of the non surgical modalities that can be used to desensitize an amputation stump neuroma?
Vibration, massage, and transcutaneous nerve stimulation
What is complex regional pain syndrome?
CRPS is a constellation of symptoms including pain at rest, vasomotor instability and swelling that results in functional impairment of the affected hand or limb. It usually is the result after trauma
What diagnostic study can help establish the diagnosis of complex regional pain syndrome?
Three phase bone scintigraphy has been shown to be highly specific for the diagnosis of CRPS in the upper extremity
What nerve is affected with Thoracic outlet syndrome?
Lower trunk of the brachial plexus with symptoms mimicking cubital tunnel syndrome
What are the contents of the thoracic outlet?
Subclavian vein, subclavian arterty, brachial plexus
In what gender is Thoracic outlet syndrome more prevalent?
Females 3.5:1
Among the population of patients with cervical ribs, how many are bilateral?
50%
When do patients with Thoracic outlet syndrome typically get their symptoms?
Symptoms worsen when hands are elevated above their head
What is the Adson maneuver?
Dampening of the radial pulse with inhalation, neck extension, and head rotation towards the affected side in patients with thoracic outlet syndrome.; False positives are common
What is Wright maneuver?
Reproduction of thoracic outlet syndrome symptoms or dampening of the radial pulse with arm hyperabduction with patient’s head neutral or turned contralateral; can be positive in 7% of normal patients
What is Roos maneuver?
Placing both arms in 90 degrees of abduction and external rotation and patient opens and closes hands for 3 minutes. Thoracic outlet syndrome patients will have reproduction of symptoms, normal patients have forearm fatigue; The most accurate of the maneuvers
What are the electrodiagnostic testing results seen with thoracic outlet syndrome?
Negative EMG for ulnar nerve, positive somatosensory -evoked potentials with arm in offending position
What is the first line therapy for thoracic outlet syndrome?
Conservative treatment with exercises to strengthen the shoulder girdle, weight loss, occasionally breast reduction in women
Name two approaches to the thoracic outlet?
Supraclavicular and transaxillary
What is similar and what is different about the presentation of thoracic outlet syndrome and cubital tunnel syndrome?
Both TOS and cubital tunnel syndrome can present with ulnar distributions of numbness, although TOS also presents with medial forearm numbness