Outline of

Neurosurgery

E. R. Flotte, 2008

Home

Please send comments and corrections to admin@flotte2.com

Peripheral Nerve

Peripheral Nerve Anatomy

Nerve injury

· See Neurosurg Focus 5/04 (Belzberg AJ et al)

· Seddon classification: Neuropraxia > Axonotmesis (perineurium and epineurium intact) > Neurotmesis.

· Sunderland classification I-V.

· Spontaneous recovery: 40% C5/6, 18% C5-7, 5% C5-T1 (flail arm)

· Motor recovery occurs within 18mos (no limit on sensory)

· EMG first performed at 2 weeks in blunt/stretch injuries

· Progressive lesions (hematoma, compartment syndrome, pseudoaneurysm) require immediate evaluation/possible surgery

· Progression of Tinel’s sign (paresthesias on tapping) may be used to follow recovery

Treatment

· Laceration: Repair within 72hrs if sharp. 2-4 weeks if blunt (to allow delineation of injury)

· Penetrating: explore when 1° wound healed.

· GSW: 2-5 mos for GSW with complete or severe lesions-in-continuity

o Early exploration is advocated by some

o Exploration primarily for upper elements (lower not as successful)

· Traction/Blunt :

o Serial EMG/NCVs (& SSEP?) every 3 months, repair if no improvement on EMG or clinically.

o Repair possible for upper elements only. Most effective if patient is <50yo.

o Also surgically explore for pain, pseudoaneurysm.

Surgical Repair

· Priorities for motor recovery are generally: elbow flexion (biceps), shoulder abduction, wrist extension, finger flexion

· Consider tourniquet (remove during intraop nerve testing). Expose normal nerve proximal & distal 1^st.

· Use 10-0 nylon. Consider fibrin glue.

· Epineurial repair is equal to fasicular repair

· Avoid traction. Use of more than 2 sutures to approximate implies unacceptable tension

· Postoperative usually immobilized for 3-6 weeks, then physical therapy

Techniques

· Neuroma: Determine need for resection by palpation (firm = worse), CNAP.

o Nerve Action Potentials (CNAP): Stimulation applied across neuroma or blunt/stretch injury site (proximal stimulation, distal recording).

o Kline: If conduction occurs then only perform neurolysis (others perform neurolysis and distal transfer, or no neurolysis but distal transfer only). If no conduction then perform graft or nerve transfer.

o Others perform graft or transfer regardless of CNAP.

o End-to-side transfer distal to neuroma has been used

· Neurorrhaphy: end-to-end repair.

· Neurolysis: Dissection with lysis of adhesions. If nerve is in continuity and shows evidence of regeneration by positive CNAP distally or muscle contraction in response to stimulation

· Neurotization (nerve transfer): Used for root avulsion.

o Avoid intervening grafts, use direct transfer when possible. Implant as close as possible to the site where function is to be restored

o Examples: elbow flexion=intercostals-to-musculocutaneous; shoulder abduction=spinal accessory-to-suprascapular

· Interposition nerve graft:

o Donors: sural, medial antebrachial cutaneous, superficial radial sensory, lateral cutaneous antebrachial, dorsal cutaneous branch of ulnar

o “Cable graft”: several smaller nerves used to repair large n.

o Synthetic nerve guides have been approved. Used for short segments (few cm). Usually resorbable (non-resorbable may cause late compression syndromes) (N10/06). Also vein conduits used.

· Burying into muscle: equivocal, reported to be efficacious by some

Complex Regional Pain Syndrome

Peripheral Nerve Sheath Tumors

· Present with pain, mass. Percussion of the mass causes paresthesias.

· 62% neurofibromas, 38% schwannomas

· In schannomas function preserved in 89% after resection

· See JN2/05

· Non-nerve sheath tumors include: ganglion cysts, hypertrophic neuropathy, lipomas, hemangiomas, and desmoid tumors. Metastases to nerves can also occur

Entrapment Neuropathies

· Pain is usually at the entrapment site, not in the distribution of the affected nerve. Parasthesias more common than numbness. Clumsiness more common than discreet weakness.

· NCV shows conduction delay across the site of entrapment

· Tinel sign: pain/paresthesias reproduced on mechanically stimulating (eg tapping) the nerve

Upper extremity

Root	Clinically Relevant Gross Motor Function
C5	Shoulder abduction; ± elbow flexion
C6	Elbow flexion, pronation/supination, ± wrist extension
C7	Diffuse loss of function in the extremity without complete paralysis of a specific muscle group
C8	Finger extensors, finger flexors, wrist flexors, hand intrinsics
T1	Hand intrinsics

Brachial Plexus

· Suprascapular n.: Shoulder abduction (first 15º). Supraspinatus/ infraspinatus. Most often repaired by spinal accessory n. transfer.

· Roots (myotomes & dermatomes) show considerable overlap, peripheral nerves have sharp boundaries

· Cords:

o Lateral = muscles to forearm and sensation of median n.

o Medial = all median and ulnar intrinsic hand muscles

Injuries

· Erbs palsy: C5 & 6/upper brachial plexus, bellhops hand

o Erb’s birth injury: Controversial whether to operate or observe

· Klumpkes palsy: C8 & T1/lower brachial plexus, claw hand

· Perinatal Brachial Plexus Palsy

· Ulnar n. vs C8 root injury: Sensation: ulnar n. splits 4^th digit, C8 covers entire finger. Motor: C8 root lesion causes loss of all intrinsic hand muscles (ulnar and median)

· Pancoast tumor: Horners + C8/T1 loss

· Suprascapular entrapment: inability to abduct shoulder first 15°

· Winged scapula:

o long thoracic n. or serratus anterior injury (lymph node biopsy): winging when arm extended (eg against wall)

o spinal accessory n. injury: winging when elbow flexed (across chest)

· Axillary n. injury: Occurs after shoulder dislocation. Impaired abduction

· Spinal accessory n.: injured in surgery of posterior cervical triangle (lymph node biopsy). Weak trapezius – impaired shoulder abduction >90^o, drooping shoulder, winging of scapula, shoulder pain. No sternocleinomastoid paralysis (trapezius only). Shoulder shrug is preserved. SAN is cephalad to great auricular n. at lateral border of SCM. (N11/03)

· Ulnar nerve has worst prognosis for return of motor function (and intrinsic hand weakness in generally usually does not recover). (Radial n. is usually best)

· Radial n. injured with mid-shaft humerus fractures. Brachioradialis improves 1^st.

· Median n.: Benedictine or papal sign - impaired flexion of thumb and index finger

Brachial Plexus Repair

· Priorities for functional improvement: elbow flexion, shoulder abduction, finger flexion, wrist extension, shoulder rotation

· Distal recovery is much more difficult to achieve

Preoperative workup

· MRI, CT-myelogram:

o Kline feels CT-myelogram are usually necessary unless MRI is conclusive for avulsion

o Meningocoeles around nerve root imply root avulsion.

o Absence of a meningocoele does not rule out an avulsion

· EMG: documents the degree and pattern of dennervation, and any signs of reinnervation

o Kline feels that SSEPs do not add any information (citation pending)

o SNAPs (sensory nerve action potentials) are preserved in avulsions since DRG is still connected to the nerve. Absent in distal injuries

· Differentiate root avulsion from postganglionic injury: Horner’s syndrome (C8/T1), paralysis of serratus anterior (winged scapula) or rhomboids, diaphragm paralysis on CXR (C3-5), absent Tinel sign, shoulder protraction test (C5), early neuropathic pain, EMG shows paraspinal deinnervation (wait >3wks), normal SNAP (lost in postganglionic lesions. More sensitive than an absent SSEP), MRI/CT shows meningocoele. (See BertelliJA JN12/06)

Root avulsion

· Most treatment is by nerve transfer.

· No spontaneous recovery. Grafting not yet feasible (experimental).

· Intraoperatively some dissect the nerve root into the foramina to prove avulsion

Obstetrical Brachial Plexus Injury