Muscular dystrophies

1. What is the inheritance of Duchenne's/Becker's MD?
2. What is the clinical presentation of MD?
3. What is seen on muscle biopsy and labs in MD?
4. What is the presentation of myotonic dystrophy?

Answers:
1. X-linked.
2. Prox muscle weakness, calf pseudohypertrophy, cardiomyopathy, mental retardation, Gower's sign, increased lumbar lordosis, abnormal MSR.
3. Biopsy shows no dystrophin (Duchenne) or decreased (Becker). Increased CPK.
4. Autosomal dominant, presents as infant. Distal weakness, hatchet face (wasting of temporalis and masseter), frontal balding, poor vision, hypertrichosis, mental retardation. Biopsy shows type I fiber atrophy and type II fiber hypertrophy.

Myopathy

1. What are seven different categories of myopathy?
2. What is the clinical presentation of myopathy?
3. What is seen on EMG in myopathy?
4. What is the utility of quantitative EMG for myopathy?
5. What is seen with rep stim and SFEMG in myopathy?
6. Which disorders show Type II fiber atrophy on biopsy?

Answers:
1. Dystrophic (Duchenne, Becker), congenital, metabolic (acid maltase deficiency), inflammatory (polymyositis, dermatomyositis), endocrine (thyroid, adrenal), toxic (alcohol, diuretics, vincristine), steroids.
2. Muscle atrophy, hypertrophy, abnormal MSR, weakness, hypotonia, gait abnormalities, or myotonia (painless delayed relaxation of muscles).
3. SNAP normal, CMAP low amplitude, EMG may show fibs, PSW, CRD, or myotonic discharges. Classic MUAPs are small duration, small amplitude due to loss of muscle fibers, but collateral sprouting may result in long duration large amplitude MUAPs. MUAPs may be unstable at the beginning of sprouting.
4. Used to calculate mean duration by using 20 MUAPs.
5. Rep stim may show a decremental response due to reduced safety factor in regenerating immature NMJs. SFEMG shows increased jitter, fiber density, and blocking.
6. Steroid myopathy, myasthenia gravis, deconditioning.

Single fiber EMG

1. When is SFEMG used?
2. What sorts of diseases cause SFEMG to be abnormal?
3. What is fiber density? What is normal density?
4. What is jitter? What is normal?
5. What is blocking? How long does it take to resolve?

Answers:
1. If rep stim of at least three muscles is normal and abnormal diagnosis is still suspected.
2. NMJ disorders, MND, peripheral neuropathy.
3. Represents the number of single fibers belonging to the same motor unit within the recording radius of the electrode. A density of 1.5 is normal, higher represents denervation and reinnervation.
4. Small variation between the interpotential discharges of two muscle fibers of the same motor unit. Normal is 10-60 u.
5. Abnormality that occurs when a single muscle fiber AP fails to appear, which occurs with jitter > 100 u. Resolves in 1-3 months, after reinnervation is completed.

High rate repetitive stimulation

1. What is the rate for HRRS? Is there any substitute for this?
2. What is the effect of HRRS?
3. What occurs as a result of HRRS in MG, LEMS, and botulism?
4. What is pseudofacilitation?

Answers:
1. 10-50Hz. May substitute maximal isometric contraction.
2. Accumulation of calcium in the cell.
3. MG shows a decrement, LEMS shows a 200-300% increment, and botulism shows a mild increment.
4. Pseudofacilitation is the progressive increase in CMAP amplitude with HRRS or voluntary contration in a normal patient, which results from synchronicity of muscle fibers (decreased temporal dispersion).

Post-activation facilitation and exhaustion

1. What is post-activation facilitation? When is it performed?
2. What is post-activation exhaustion? When is this test performed?

Answer:
1. PAF is a 10 second isometric contraction (or tetany-producting stim of 50 Hz) that is done if decrement is noted on LRRS.
2. Response seen as CMAP amplitude decreases, which occurs with a LRRS performed every minute for 5 mins after initial isometric contraction. This test should be used if there is no decrement with LRRS, but a neuromusc junction disorder is still suspected.

Repetitive nerve stimulation

1. What muscles are stimulated in repetitive stim?
2. What decrease in amplitude is significant?
3. What rate is used for low rate repetitive stim (LRRS)?
4. What happens if the safety factor is decreased in LRRS?
5. What is the amplitude change for LRRS in MG, LEMS, and botulism.

Answers:
1. ADM/APB, deltoid, trapezius, orbicularis oculi.
2. Greater than 10% decrease from 1st to 5th waveform.
3. 2-3 Hz.
4. Each stimulus causes the EPP amplitude to drop, so a reduced safety factor will result in the potential falling below the threshold for activation --> reduced MUAP amplitude.
5. All three disorders result in a >10% drop in amplitude.

Botulism

1. What is the mechanism behind botulism?
2. When does botulism occur after ingestion?
3. What is the presentation of botulism?
4. What does EMG show?
5. What is the treatment for botulism?

Answers:
1. Toxin blocks exocystosis of ACh from nerve terminal.
2. Begins 2-7 days after ingestion.
3. Bulbar symptoms first (ptosis, dysphagia, dysarthria), diarrhea, N/V, widespread paralysis or flaccidity, abnormal MSR, respiratory and cardiac dysfunction.
4. SNAP normal, CMAP reduced amplitude, unstable MUAP.
5. Trivalent ABE antitoxin, wait for collateral sprouting.

Lambert-Eaton Syndrome

1. What is the mechanism behind LES?
2. What is the presentation of LES?
3. What does muscle biopsy show?
4. What are the EMG findings in LES?
5. What is the treatment of LES?

Answers:
1. Autoimmune attack on the presynaptic membrane, decreasing Ca entry into the cell and decreased release of ACh. Associated with small cell lung cancer.
2. Proximal fatigue and weakness, LE>UE, abnormal MSR, exacerbated with rest and improved with exercise, rarely involves neck or face or bulbar.
3. Overdevelopment of neuromuscular junction.
4. Normal SNAP, low amp CMAP, unstable MUAP.
5. Treat underlying malignancy, corticosteroids, immunosuppression, plasmapheresis, guanidine (incr ACh quanta).

Myasthenia gravis

1. What is the etiology of MG?
2. What is the presentation of MG?
3. How is it diagnosed?
4. What are the findings on standard EMG for MG?
5. What is the treatment of MG?

Answers:
1. Autoimmune response to the ACh receptors on the post-synaptic membrane. Often associated with thymic disorder.
2. Proximal fatigue and weakness, exacerbated by exercise, heat, or later in the day, improved with rest. Normal MSR. Ptosis, diplopia, dysphagia, dysarthria.
3. Tensilon test: 2mg of edrophonium followed by 8mg dose, improvement in 1 min. Muscle bx shows loss of postsyn junction folds and receptors. Blood shows anti-ACh receptor ab.
4. SNAP and CMAP are normal. EMG shows unstable MUAP.
5. Thymectomy, anticholinesterase drugs, corticosteroids, immunosuppressive agents, plasmapheresis. 1/3 improve spontaneously.

HIV neuropathy

1. What are the 5 major categories of HIV neuropathy?
2. Is HIV demyelinating or axonal?
3. What does the EMG show?

Answers:
1. Distal symmetric polyneuropathy (most common), inflammatory demyelinating polyneuropathy, mononeuropathy multiplex, progressive polyradiculopathy, autonomic neuropathy.
2. Both.
3. CMAP, SNAP, and EMG are abnormal.

Diabetic neuropathy

1. What is the presentation of diabetic neuropathy? What sort of neuropathy is it?
2. What is seen on nerve biopsy?
3. What is seen on EMG?

Answers:
1. Like uremia, this is a mixed axonal/demyelinating neuropathy. It presents with sensory abnormalities.
2. Small and large fiber abnormalities.
3. SNAP, CMAP, and EMG all abnormal.

Alcoholic neuropathy

1. What is the presentation of alcoholic neuropathy?
2. What does nerve biopsy show?
3. What does EMG show?
4. What is the treatment?

Answers:
1. Sensory abnormalities, foot or wrist drop, muscle spasms, Korsakoff's/Wernicke's syndrome. May be associated with a myopathy.
2. Wallerian degeneration.
3. SNAP and CMAP abnormal. EMG shows abnormal activity.
4. Vitamins, diet, stop alcohol, orthotics.

Friedreich's ataxia

1. What is the inheritance of Friedreich's ataxia?
2. What is the onset time?
3. What are the characteristics of Friedreich's ataxia?
4. What does nerve biopsy show? What does EMG show?
5. What is the prognosis?

Answers:
1. Autosomal recessive
2. 2-16 years.
3. Abnormal sensation and weakness, abnormal MSR, ataxia, optic atrophy, kyphoscoliosis, dysarthria, pes cavus, cardiomyopathy.
4. Nerve bx shows abnormal large axons. SNAP is abnormal, CMAP is normal, with EMG showing abnormal acitivity.
5. WC use by age 16.

Charcot-Marie-Tooth (CMT)

1. What is the presentation of Hereditary Motor Sensory Neuropathy I (HMSN-I, Charcot-Marie-Tooth)?
2. What are the lab findings in CMT?
3. What are the EMG findings in CMT?
4. What is the treatment for CMT?

Answers:
1. CMT is an autosomal dominant disease that presents in early childhood. It is slowly progressive and sensory loss is more apparent in LEs than UEs, there is abnormal vibration and proprioception, intrinsic foot atrophy resulting in pes cavus and hammer toes, bilateral foot drop resulting in steppage gait, stork leg appearance, and essential tremor.
2. CSF has increased protein. Nerve biopsy shows onion bulb formation.
3. SNAP is abnormal. CMAP is abnormal with CV less than 70% of normal. EMG may be normal or show signs of reinnervation.
4. Treatment is rehab and orthotics.

Peripheral neuropathy

1. What are the demyelinating polyneuropathies?
2. What are the axonal polyneuropathies? Of these, which have sensory and which have motor findings?
3. What polyneuropathies have both demyelination and axonal loss?

Answers:
1. HMSN-I, III, IV (e.g. Charcot-Marie-Tooth), leukodystrophy, AIDP, CIDP, arsenic, toxins, monoclonal gammopathy, diphtheria, AIDS, leprosy, Lyme disease.
2. Motor: porphyria, vincristine, lead, Dapsone, HMSN-II. Sensory: cisplatinum, Freidreich's ataxia, HSN, Sjogren's, pyridoxine, Crohn's. Sensorimotor: amyloidosis, EtOH, Vit B12, folate, toxins, gold, mercury, paraneoplastic syndrome, sarcoid, Lyme, HIV.
3. DM, uremia.

Finger fractures

1. What is a Bennet's fracture?
2. What is a Rolando's fracture?
3. What is a Boxer's fracture?
4. What is the treatment for finger fracture?

Answers:
1. Oblique fracture or subluxation at the base of the thumb metacarpal.
2. T, Y, or comminuted fracture at the base of the thumb metacarpal.
3. Fracture of metacarpal neck/shaft, often from punching, most commonly seen in 5th digit.
4. Orthopedic referral.

Mallet finger

1. What is the mechanism of mallet finger?
2. What are the symptoms?
3. What is the treatment of mallet finger?

Answers:
1. Sudden passive DIP flexion with finger extended, causing extensor tendon rupture.
2. Flexed DIP joint that can't be actively extended, tenderness and edema in the distal dorsal area.
3. Splinting of DIP in extension for 6-8 wks, followed by 2-4 wks of gentle active flexion with night splinting. Surgical repair if there is poor healing or if there is an avulsed fragment involving > 1/3 of the joint.

Flexor digitorum injury

1. What are causes of flexor digitorum injury (Jersey finger)?
2. What is seen clinically in flexor digitorum injury?
3. What may be seen on imaging?
4. What is the treatment?

Answers:
1. Injury to the FDP or FDS may occur spontaneously in RA or trauma (finger gets caught in the jersey of another player when attempting to grab him.
2. Inability to actively flex DIP.
3. Plain film may show avulsed fragment near tendon insertion.
4. Early surgical repair.

Ligamentous injuries

1. How is the collateral ligament of the finger injured?
2. How is the volar plate injured?
3. How is the ulnar collateral ligament injured (Gamekeepers thumb, Skier's thumb)?
4. What is the treatment of ligamentous injury of the fingers?

Answers:
1. Valgus or varus stress of extended finger.
2. Hyperextension with dorsal dislocation.
3. Valgus stress of thumb at MCP jt.
4. Conservative treatment involves reduction, buddy splinting for 2wks and thumb spica splint for 3-6wks for MCP injury. Surgery for complex lesions.

Trigger finger (Stenosing tenosynovitis)

1. What is the mechanism of trigger finger?
2. What are predisposing factors for trigger finger?
3. What is seen clinically?
4. What is the treatment?

Answers:
1. Repetitive trauma resulting in inflammation of flexor tendon sheaths of digits, resulting in a nodule in the tendon and abnormal glide. This nodule gets caught on the annular sheath.
2. Repetitive trauma, DM, RA, >40yrs.
3. Catching or locking with finger flexion. Palpable nodule.
4. Immobilization by splinting, NSAIDs, steroid injection. Surgical release if conservative treatment fails.

Dupuytren's contracture

1. What is the mechanism of Dupuytren's contractures?
2. What factors predispose to Dupuytren's contractures?
3. What is seen clinically?
4. What is the treatment?

Answers:
1. Thickening of the palmar fascia due to fibrous proliferation.
2. Genetics (Northern Europeans), DM, EtOH, epilepsy, pulmonary TB, men > 40.
3. Painless nodules in distal palmar crease, initially nontender but may become tender. Involved finger may be drawn into flexion.
4. US, splinting, massage, possible surgical release if severe.

Scaphoid fracture

1. What is the usual mechaism of a scaphoid fx?
2. What are complications of a scaphoid fx?
3. How are scaphoid fx's classified?
4. What is seen clinically in scaphoid fx?
5. What are the borders of the anatomical snuff box?
6. What imaging is done to assess scaphoid fx?
7. What is the treatment of scaphoid fx?

Answers:
1. Fall on dorsiflexed wrist.
2. Osteonecrosis due to poor blood supply (supply is mainly to the distal 1/3 of bone) with carpal collapse.
3. By location: tubercle, distal pole, waist, proximal pole.
4. Swelling and tenderness around anatomical snuff box.
5. Base is scaphoid bone, lateral is APL and EPB, medial is EPL.
6. Plain films in ulnar deviation.
7. Fx may not appear on X-ray so treat anyway if suspicioius. If nondisplaced (<2mm),>2mm or not healing, need to consider surgery.

Distal radius fracture

1. What is the most common type of distal radius fracture?
2. What are other types of distal radius fracture?
3. What is the usual mechanism of distal radius fx?
4. What is the treatment of distal radius fx?

Answers:
1. Colles fx: fracture of distal radius with DORSAL angulation.
2. Smith's fx: fx of distal radius with VOLAR angulation (reverse Colles).
3. Fall on an outstretched arm.
4. Ortho referral for closed reduction.

Osteonecrosis of the lunate

1. What is another name of osteonecrosis of the lunate?
2. What is osteonecrosis of the lunate? What are predisposing factors?
3. What is seen clinically?
4. What imaging is used for diagnosis?
5. What is the treatment?

Answers:
1. Klenbock's disease.
2. Idiopathic loss of blood supply to lunate, causing necrosis of the bone and degenerative changes. Etiology is likely repetitive trauma or possibly short ulna.
3. Ulnar sided pain and swelling over dorsal wrist, reduced grip strength.
4. Plain films may show fracture/flattening/sclerosis of lunate, bone scan, MRI.
5. Ortho referral.

Ganglion cyst of the wrist

1. What is a ganglion cyst?
2. What is seen clinically?
3. What is the treatment?

Answers:
1. Cyst that arises from the synovial sheath of the joint and is filled with synovial fluid.
2. Small smooth mass, pain with pressure or ranging of wrist.
3. Immobilization, aspiration of cyst (90% recur), surgical removal (10% recur).

DeQuervain's tenosynovitis

1. What is the mechanism of DeQuervain's?
2. What is seen clinically?
3. What is Finkelstein's test?
4. What is the treatment of DeQuervain's?

Answers:
1. Repetitive or direct trauma to the sheath of the EPB and APL (first extensor compartment of the wrist).
2. Pain and tenderness on the radial side of the wrist.
3. Flex thumb into palm of hand, making a fist, while examiner ulnarly deviates the wrist. Pain is positive.
4. Thumb spica splint, NSAIDs, steroid injection. ?Surgery.

Arthritis of the wrist

1. What are two different kinds of arthritis that affect the wrist?
2. What is seen clinically in Rheumatoid arthritis?
3. What is a swan-neck deformity?
4. What is Boutonniere's deformity?
5. What is seen clinically in osteoarthritis?
6. Where is wrist osteoarthritis most common?

Answers:
1. Rheumatoid arthritis (autoimmune attack on synovial tissue, which destroys the articular cartilage and leads to bone destruction) and osteoarthritis (deterioration of articular cartilage and formation of new bone at joint margins).
2. Swelling of the wrists, MCP and PIP, ulnar deviation of the wrist, dorsal subluxation of the ulna, erosion of the ulnar styloid.
3. Contracture of hand intrinsics, resulting in MCP flexion, PIP hyperextension, DIP flexion.
4. Tearing of the extensor hood, resulting in MCP hyperextension, PIP flexion, and DIP hyperextension.
5. Heberden's (DIP) and Bouchard's (PIP) nodules, tenderness along the area of involvement and crepitus of the wrist, cyst formation in the joint space.
6. First CMC joint.

Wrist anatomy

1. What are the carpal bones?
2. What are the wrist flexors?
3. What are the wrist extensors?
4. How many extensor compartments are there in the wrist?

Answers:
1. Proximal: Scaphoid, Lunate, Triquetrum, Pisiform; Distal: Trapezium, Trapezoid, Capitate, Hamate. (Some Lovers Try Positions That They Can't Handle)
2. FCR, FCU, palmaris longus, FDS, FDP, FPL.
3. ECRL, ECRB, ECU, extensor digitorum, EDM, EIP, EPL.
4. Six.

Olecranon fracture

1. How does an olecranon fracture usually occur?
2. What is a possible complication of olecranon fx?
3. How is an olecranon fx treated?

Answers:
1. Direct blow to elbow, fall on elbow with elbow flexed, or fall on outstretched arm.
2. Ulnar nerve involvement.
3. Nondisplaced fractures are immobilized. Displaced fractures are treated surgically.

Radial head fracture

1. What sort of elbow injury often is associated with radial head fractures?
2. How does a radial head fx usually occur?
3. How many types of radial head fx's are there? How are they treated?

Answers:
1. Elbow dislocation.
2. Fall on outstretched arm.
3. Type I (nondisplaced) is treated with short immobilization (3-5days) and early ROM. Type II (min displaced) is fixed surgically if there is greater than 2mm displacement or 30% radial head involvement. Type III (comminuted) is treated surgically.

Humeral fractures

1. What sort of nerve injury is associated with humeral shaft fracture?
2. How are humeral shaft fractures treated?
3. How are distal humerus fractures classified?
4. What are complications of a distal humerus fracture?
5. How is a distal humerus fracture treated?

Answers:
1. Radial nerve injury, 95% of which recover in 6 mo.
2. Splint for 2 wks.
3. Displaced or nondisplaced.
4. Neurovascular injury, nonunion, malunion, elbow contracture, poor ROM.
5. Displaced fractures require open reduction. Nondisplaced fractures can be splinted.

Osteochondrosis dissecans of the elbow

1. What is another name for OD of the elbow?
2. What is seen clinically?
3. What is seen on imaging?
4. What is the treatment?

Answers:
1. Panner's disease.
2. Tenderness and swelling in lateral elbow, limited extension on ROM, usually in young boys.
3. Plain films show sclerosis and patchy areas of lucency with fragmentation.
4. Immobilization, then gradual ROM.

Radial/Ulnar collateral ligament sprain

1. How does radial vs. ulnar collateral ligament sprain occur?
2. What is seen clinically in UCL sprain? How is it tested?
3. What is seen clinically in RCL sprain? How is it tested?
4. What imaging is used for UCL/RCL sprain?
5. How are collateral ligament sprains treated?

Answers:
1. UCL sprain occurs via valgus stress across elbow during a throw. RCL sprain occurs via traumatic elbow dislocation.
2. Medial elbow pain after a throw, pop or click, pain with valgus stress test (medial elbow tenderness, increased with valgus stress).
3. Recurrent locking or clicking of the elbow with extension and supination, pain with varus stress test (medial elbow tenderness, increased with varus stress). The lateral pivot-shift test is also used to assess the RCL for posterolateral instability.
4. Plain films, varus (RCL) and valgus (UCL) stress radiographs will show 2mm joint space.
5. Rest ice, NSAIDs, strengthening and stretching rehab, return to play criteria. Surgery if needed.