Ch31 Non-entrapment neuropathies

Question 1

What is the difference between a poly and mononeuropathy?

Answer 1

Multiple vs single nerve peripheral neuropathy resulting in weakness, sensory disturbance and abnormal reflexes.

Question 2

What are the causes of peripheral neuropathies?

Answer 2

Mnemonic GRAND-THERAPIST: GB, Renal failure, Alcohol, Nutritional deficiencies, DM Trauma, Hereditary, Entrapment, Radiation, Amyloid, Porphyria/paraneoplastic, Infection (leprosy), Sarcoid and Toxins

Question 3

What are the inherited neuropathies?

Answer 3

Charcot-Marie-Tooth; 7 types mostly AD. Types 1 and 2 are most common. Results in LL motor>sensory deficits. Type 1 continue to ambulate but Type 2 loose ambulation as teenagers.

Question 4

What % of critical care neuropathies resolve completely?

Answer 4

50%

Question 5

What is the classical finding of ETOH neuropathy?

Answer 5

Diffuse sensory loss with loss of ankle jerk

Question 6

What are the causes of a brachial plexus injury?

Answer 6

Trauma Pancoast tumour Cervical rib (thoracic outlet syndrome) DM Vasculitis Viral Inflammatory - Parsonage-Turner syndrome

Question 7

What is the presentation of Parsonage-Turner syndrome?

Answer 7

Intense pain with development of weakness within 2 weeks (80% had a sudden onset of weakness). 50% have a viral prodrome. 50% are confirmed to the shoulder girdle.

Question 8

How can multi-level radiculopathy be distinguished from a plexopathy with EMG?

Answer 8

Sampling of the paraspinal muscles with EMG shows involvement with radiculopathy but not plexopathies

Question 9

What causes lumbosacral plexus neuropathy?

Answer 9

Diabetes. Associated with tenderness over the femoral nerve. If L4 is involved (knee ext weakness) can be mistaken for femoral nerve injury. If L5 is involved (foot drop) can be mistaken for common peroneal nerve injury.

Question 10

How does diabetic neuropathy present? (3 types)

Answer 10

Primary sensory polyneuropathy (glove and stocking) Diabetes proximal neuropathy Autonomic neuropathy (bladder dysfunction and orthostatic hypotension)

Question 11

What are the features of femoral neuropathy?

Answer 11

Femoral nerve root supply = L2,3,4 Weakness with hip flexion and knee extension. Loss of knee reflex and numbness over the anterior thigh / medial calf. Positive femoral stretch test!

Question 12

What are the causes of femoral neuropathy?

Answer 12

Diabetes, femoral entrapment (hernia repair), intra-abdominal tumour, retroperitoneal haematoma.

Question 13

What are the monoclonal gammopathies?

Answer 13

Mulitple myeloma Waldenstrom’s macroglobulinaemia Monoclonal gammopathy of undetermined significance

Question 14

What position causes maximal stretch of the ulnar nerve in the cubital tunnel retinaculum?

Answer 14

Flexion

Question 15

What is a lower trunk brachial plexus neuropathy commonly mistaken with?

Answer 15

Ulnar neuropathy

Question 16

What are amyloid deposits?

Answer 16

Insoluble extracellular protein aggregates that can be deposited in peripheral nerves. Occurs in 15% of patients with multiple myeloma. Causes autonomic dysfunction and symmetric dissociated sensory loss.

Question 17

What neuropathies may result from groin catheter puncture haematomas?

Answer 17

Femoral neuropathy (hip flexion and knee ext weakness) Obturator neuropathy (adductor weakness and groin numbness) Lateral femoral cutaneous nerve (meralgia paraesthetica)

Question 18

How do you treat neuropathies secondary to groin catheter puncture haematomas?

Answer 18

Conservative

Question 19

Label the anatomy of a peripheral nerve.

Answer 19

With labels

Question 20

What are the classification systems for peripheral nerve injury?

Answer 20

Seddon and Sunderland classifications

Question 21

What is the Seddon classification?

Answer 21

Neuropraxia - nerve in continuity, compression or ischaemia causing local conduction block.

Axontomesis - Complete interruption of axons and myelin sheaths. Endoneurium intact. Associated with Wallerian degeneration occurs

Neurotmesis - complete transection of the nerve with loss of continuity. Spontaneous regeneration not possible.

Question 22

What is the Sunderland classification?

Answer 22

Ranges from 1st - 6th degree with 1st degree being a focal demyelination and 6th degree being a complete transection. Note: Sunderland 1 = neuropraxia, Sunderland 2-4 = axonotmesis and Sunderland 5-6 = Neurotmesis.

Question 23

What are the causes of a brachial plexus injury?

Answer 23

Trauma

Traction

Cervical rib

Haematoma

Question 24

What does a Horner’s syndrome in addition to a brachial plexus injury suggest?

Answer 24

Preganglionic injury (interruption of white rami communicans / sympathetic chain).

Question 25

What does Serratus anterior (long thoracic nerve) and Rhomboid (dorsal scapular nerve) muscle weakness suggest?

Answer 25

The injury is proximal to the brachial plexus (preganglionic)

Question 26

What is Erb's palsy?

Answer 26

Waiter's tip position with adducted and internally rotated arm, elbow extension and wrist flexion. Caused by upper brachial plexus injury (C5/6) resulting in deltoid, biceps, supra and infraspinatus injury. Hand function is unaffected.

Question 27

What is Klumpke's palsy?

Answer 27

Lower brachial plexus injury (C8/T1) - look for a pancoast tumour esp if Horner's syndrome! Weakness and wasting of the small muscles of the hand resulting in claw deformity.

Question 28

Which brachial plexus injury is seen with birth trauma?

Answer 28

Erb's palsy (upper trunk C5/6)

Question 29

How do you manage a brachial plexus injury due to a compressive haematoma?

Answer 29

Immediate exploration

Question 30

How do you manage a brachial plexus injury due to a clean cut?

Answer 30

Tension free end to end anastomosis within 24-48 hours

Question 31

How do you manage a brachial plexus injury due to a gunshot wound?

Answer 31

Conservative for 6 months. After that grafts or tendon transfers.

Question 32

How do you manage a brachial plexus injury due to traction injury?

Answer 32

Do EMG at 6 months. Incomplete post-ganglionic injuries tend to improve spontaneously. If no improvement then explore and graft / tendon transfer.

Question 33

How do you manage a brachial plexus injury due to a neuroma in continuity?

Answer 33

a. neurolysis (if SNAP intact) b. nerve graft (if SNAP absent) c. nerve transfer (if SNAP absent)

Question 34

What are the donor sites for nerve transfers with brachial plexus injury?

Answer 34

Spinal accessory Intercostal nerves to musculocutaneous Ulnar nerve fascicles to the median nerve AIN to the median nerve

Question 35

What are the features of thoracic outlet syndrome?

Answer 35

Arterial - UL pallor / ischaemia Venous - UL congestion / oedema Nerve - Lower trunk Muscle - Scalenus (anticus) syndrome

Question 36

Is thoracic outlet syndrome more common in men or women?

Answer 36

Women

Question 37

What investigations would you perform for suspected thoracic outlet syndrome?

Answer 37

EMG - confirms muscle denervation pattern. NCS may show loss of the medial antebrachial cutaneous SNAP. MRI of brachial plexus may show a kink in the lower trunk Cervical spine x-rays with oblique views

Question 38

What is the surgical treatment for thoracic outlet syndrome?

Answer 38

Scalaenectomy and resection of the 1st rib