A. Neuropraxia
1. Focal conduction block
2. Local myelin injury, primarily larger fibers
3. Axon intact
4. No wallerian degeneration
5. Recovery in weeks to months
B. Axonotmesis
1. Loss of nerve conduction at injury site and distally
2. Disruption of axonal continuity with wallerian degeneration
3. Connective tissues intact
4. Strength return through sprouting (if incomplete) and/or nerve regrowth
5. Prognosis can be good
C. Neurotmesis
1. Same as for axonotmesis
2. Severance of the entire nerve
3. Surgical connectin of nerve ends required
4. Prognosis guarded at best
A. Carpal Tunnel Syndrome
A 35-year-old female presents to your office with an 8-week history of right hand pain. The pain is associated with numbness and paresthesias in the right thumb and index finger. The symptoms are intermittent and wake her up at night. She shakes her wrist out when she is awoken by the symptoms and this gives her some relief. She recently gave birth to her first child. Her job involves a lot of typing on a computer keyboard.
On physical examination she has diminished 2 point discrimination and pinprick sensation in the right median nerve distribution. She has no atrophy of any muscle group and her strength is normal except for slight weakness of her right APB. Her reflexes are symmetric. She has positive Tinel's sign and Phalen's sign.
1. Workup Electrodiagnostic Studies - impression:
a. abnormal study
b. Slowing across the carpel tunnel of the median sensory and median motor nerve without loss of amplitude are consistent with an early carpal tunnel syndrome
c. No evidence of a cervical radiculopathy
2. Definition:
a. A group of signs and symptoms secondary to dysfunction of the median nerve within the carpal tunnel.
3. Prevalence: - 55-125 cases per 100,000 the most common nerve entrapment
4. Risk Factors: - female > male (3:1)
- Repetitive activity involving the wrist
- Pregnancy
- RA, thyroid, diabetes
5. Classification
a. Early
1) numbness, paresthesias, pain in the median nerve distribution
2) symptoms are intermittent and worse at night (shaking wrist out in the middle of the night is common)
b. Intermediate
1) Continuously diminished sensation in the median nerve distribution
2) Reduced ability to manipulate fine objects
3) Tendency to drop objects
4) Can have burning sensation of the hand
5) Physical examination reveals decreased sensation in the median nerve distribution; mild thenar wasting
c. Advanced
1) Sensory and muscle atrophy are severe
2) Hand function has been affected
6. Treatment
a. Early
1) NSAID, wrist splints and corticosteroid injection (conservative intervention)
b. Intermediate
1) can try the above conservative intervention, but patients respond best to surgical release at the transverse carpal ligament
c. Advanced
1) surgical decompression of the transverse carpal ligament
B. Lumbosacral Radiculopathy
A 26-year-old female presents with a 6 months history of back and left lower extremity pain. The pain is most severe in the buttock region, and it is deep and has a burning quality. The pain radiates to her calf. She represents a pharmaceutical company and spends many hours driving a car. She has to frequently load and unload her car with product samples. She also complains of numbness involving the left lateral foot and leg. Climbing stairs has become very difficult for her, but she doesn't know the reason.
Physical examination reveals decreased sensation on the lateral foot. Her left ankle jerk is diminished. She can walk on her left heel but cannot perform 5 toe rises on the left. She squats but on retum to stand she has some difficulty and she shifts her weight to the right.
1. Workup:
a. Electrodiagnostic studies impression:
1) Abnormal study
2) Subacute left S, radiculopathy
b. MRI results: a large herniated nucleus pulposus at the L5S, level with degeneration disc disease at L34 L45
2. Epidemiology
a. 85% of Americans will have low back pain sometime during their lives.
b. 5%-10% of the causes of low back pain are due to lumbar radiculopathies
c. L5 followed by S1 are the most commonly affected nerve roots in radiculopathies
3. Conservative Treatment
a. Bedrest: No
b. NSAIDs: for 2 weeks and then re-evaluate
c. Other medications: Neurontin, TCAs, Trazodone, Tegretol, narcotics
d. Epidural steroid injections: Up to 3/year
e. Physical therapy: to include McKenzie techniques, body mechanics work station evaluation, flexibility, strengthening, HEP
f. Braces: not recommended
4. Treatment
a. Absolute indication for surgery:
1) bowel/bladder incontinence
2) saddle numbness
3) progressive weakness
b. Relative indication for surgery:
1) Continued symptoms despite adequate conservative management
2) Time ?
5. How long should a patient be given a trial of conservative treatment before surgery is appropriate?
Answer: it depends on the patient when there is a relative indication for surgery
6. Outcomes
a. Surgery: 56-90% Good to Excellent
b. Conservative: 70-90% Good to Excellent
c. Comparing surgery and conservative: outcomes are equal
C. Peroneal Neuropathy at the Fibular Head
55-year-old woman presents with a 3 week history of right sided foot drop after waking up from sleeping on a chaise lounge outdoors at a party. She admits to drinking alcohol at the party. Now she has difficulty walking and easily falls because of the right foot drop. She has no back pain. There is a sensory loss over the dorsum of her right foot and the lateral aspect of the right leg.
Physical examination reveals 0/5 ankle dorsiflexion, 2/5 ankle eversion, 5/5 ankle inversion and normal strength of all other muscles tested. Sensation is reduced to pinprick and light touch over the dorsum of the right foot, including the first web space, and over the lateral aspect of the right leg. All reflexes are present and symmetrical.
1. Workup:
a. Electrodiagnostic study impression:
1) Abnormal study.
2) Evidence of an acute peroneal neuropathy at the fibular he (mostly neuropraxic) with a good prognosis for recovery
3) No evidence of a lumbosacral radiculopathy, plexopathy or sciatic neuropathy
2. The most common focal neuropathy in the lower extremities
a. Typical presentation:
1) foot drop and weak ankle eversion
2) steppage and slippage gait
3. Etiology
a. Compression: habitual leg crossing, precipitous weight loss, hard mattress or bed railing in patients who are debilitated, comatose, or under the influence of drugs/alcohol
b. Trauma: bullet wounds, lacerations and distal femur fractures
c. Occupation: walking in the squat position to plant or pick crops (strawberry pickers palsy)
d. Other: ankle sprains, proximal fibular fractures, knee dislocations, after total knee or hip arthroplasties
4. Treatment
a. Etiology specific
1) Compression: eliminate offending agent
2) Trauma: if there is a suggestion of nerve section (arrow) surgery
b. Generally
1) The majority of peroneal nerve injuries are incomplete and patients will have a functional return
2) Orthoses: to assist with footdrop
3) Prevention: to avoid further compression of the nerve eg, ICU
D. Cervical Radiculopathy
The patient is a 40-year-old mechanic who slipped on a wet greasy floor two weeks prior to being seen. He tried to prevent the fall by grabbing an overhead beam. This caused his neck to jerk strongly and he felt something snap in his neck. He now presents with persistent neck pain referred down the arm that is associated with numbness of his thumb.
On physical exam, sensation is decreased in the thumb. He has some weakness of resisted external rotation of the right shoulder and abduction of the shoulder, especially through the first 30E. On resisted forward thrust of an outstretched arm there is slight winging of the scapula. Otherwise, strength is normal. He has an asymmetric biceps muscle stretch reflex with the right being less active than the left.
1. Workup
a. Electrodiagnostic studies: Performed 3 weeks after the injury impression:
1) Abnormal study
2) Evidence of an acute right C6 radiculopathy
b. MRI: 5mm HNP at the C. level. Otherwise, normal MRI with no encroachment on the thecal sac
2. Epidemiology
a. 2nd to lumbosacral region in percentage of radiculopathies (cervical=5-36%, lumbosacral = 62-90%)
b. C7 followed by C, is the nerve roots most commonly involved
3. Conservative treatment
a. Similar to lumbosacral
b. Bracing: can be helpful for periods of time
4. Treatment
a. Absolute indication for surgery
1) Signs of a cervical myelopathy
2) Progressive neurologic deficits
3) Disc extrusion
b. Relative indication for surgery
1) continued intractable pain despite adequate conservative management and pain correlates with a recognizable clinical and radiologic pain generator
5. How long should patients be given conservative treatment before surgery is appropriate?
a. patient specific
6. Outcomes
a. Surgery: good to excellent results in 64-90%
b. Conservative: between 80-90% of patients respond well
c. Comparing surgery to conservative: No studies
E. Ulnar Neuropathy at the Elbow
A 46-year-old anesthesiologist has gradually noted mild but progressive weakness in his right hand and numbness in the ring and little finger, He comes to see you after his wife commented on the wasting in his right first web space. His numbness is constant and involves both dorsal and palmar aspects of the little finger and palm but does not extend proximally. He has no other symptoms in his other limbs and denies neck pain except when working with certain surgeons in the operating room.
Physical examination reveals wasting in the hypothenar and first web space. Strength is 4/5 in finger abduction and adduction and thumb adduction. Sensation is decreased over the little finger and ulnar aspect of the hand. All muscle stretch reflexes are easily elicited and symmetrical.
1. Workup
a. Electrodiagnostic study: Impression
1) Abnormal study
2) Evidence of an ulnar neuropathy at the elbow
3) No evidence of a cervical radiculopathy
2. Ulnar nerve compromise about the elbow is second to CTS in upper extremity focal neuropathies
3. Risk Factors
a. repeated elbow flexion or extension eg. truck drivers
b. leaning on the elbow eg, students when they study
4. Categories
a. Intermittent symptoms of mild paresthesias and hypesthesias
b. Persistent sensory complaints with some degree of intrinsic muscle weakness
c. Marked sensory loss, weakness, and muscle atrophy
5. Treatment
a. Conservative: -NSAIDs, rest and splinting of the elbow in extension
b. Surgery: - resection of arcuate ligament
1) medial epicondylectomy
2) transposition of the ulnar nerve
3) decision on which procedure may not be determined until the time of the operation
A. Why order an EMG and not go straight to an MRI?
1. An MRI takes a picture in time while an EDx evaluates the physiology of the neuromuscular system.
2. 39% of patients had different diagnoses after the EDx from that of the referring physician. (Kothari et a12006)
B. How quickly should an EMG be ordered after a patient presents to your office with clinical findings?
1. The highest yield will be obtained at 3-4 weeks post onset of symptoms.
C. What are the indications to do an EDx study in a patient with obvious carpal tunnel syndrome?
1. There are many people that have carpal tunnel rebuses followed by ulnar nerve transpositions who finally have relief of their symptoms after they undergo a cervical laminectomy/discectomy.