brachial plexus palsies Flashcards
Plexus brachialis
Anatomy
Summary:
- 5 Zones: spinal nerve roots, trunks, divisions, cords and terminal branches
- C5-6 upper trunk, C7 middle trunk, C8-Th1, lower trunk
- anterior division of upper and middle trunk - lateral chord
- posterior division of all trunks - posterior chord
- anterior division of the lower trunk - medial chord
- lateral and medial chord - n. medianus
- lateral chord terminates into the n. musculocutaneus
- medial chord terminates into the n. ulnaris
- posterior chord terminates into n. axillaris and the n. radialis
- omohyoid muscle separates the posterior triangle into a superior, omotrapzial triangle and an inferior, omoclavicular triangle
- upper and middle trunk and their divisions lies in the omotrapzial triangle
- lower trunk lie in the omoclavicular triangle
- upper, middle and lower trunk ramify into their respective divisions posterior to the clavicle
- divisions form chords which lies around the a. axillaris with name based on the relationship to the a. axillaris
convergence of C5 and C6 called Erb’s point
Clinical examination
after 3 weeks - complete Wallersche degeneration - no changing of the injury
after 6 Month - end of the golden period of the primary brachial plexus surgery (primary repair, grafting, nerve transfer) - at this point muscle or tendon transfers are the treatment options
History of plexus brachialis injury
- the energy and thus the severity of the injury
- nature and radiation of pain
- presence of reinnervation
- patient’s social circumstances
motorcycle accidents are the most cause for brachial plexus injury in 82%, sport too, 50% football players - traction to the arm,
Physical examination
4 questions:
- what is the extend of the injury (partial or complete)
- level of injury (proximal musculature preserved
- what is the severity of the injury (avulsion or a rupture)
- what are the time related changes (recovery)
C5 - supraspinatus, infraspinatus, deltoideus
C6 - biceps
C7 - triceps and the forearm extensors
C8 and T1 - flail hand - digital flexors and intrinsic function is absent
Inspection
root avulsion:
C5,6, and maybe 7 - scapula winging and wasting trapezius
C8 and T1 - Horner syndrome
cervical scoliosis - ruptur of the posterior branches of the spinal nerves innervating the neck musculature
dry skin in an anaestetic area - suggest a post-ganglionic lesion, normal moisture pre-ganglionic lesion
Palpation
important is the testing of dermatomes
C7 - middle finger
C6 - supplies the thumb
C5 - the lateral arm
C8 - the little finger
T1 - the medial forearm
testing the muscles:
avulsion or rupture? avulsion can only treated with nerve transfers, whereas ruptures can be treated with nerve repair with grafting
- (C4) phrenic nerve - diaphragma
- (C5) long throcic nerve - serratus anterior muscle (C5, C6, C7 and maybe C8) - scapula winging with margo inferior pulls backwards to the spine (trapezius winging - margo inferior moves laterally) - when both muscles are paralysed the inferior margo goes up
- (C5) - dorsal scapular nerve innervates the rhomboid and the levator scapulae - both muscles moves the scapula medial to the spine (antagonist of the serratus anterior)
BPI facts
- open, closed or caused by a gunshot
- 2 weeks are required for both antegrade and retrograde Wallerian degeneration
- another 2 weeks for sprouding of the proxima stump
- growth 1mm per day
- options for neural reconstruction include external and internal neurolysis, direct nerve repair, repair with cable grafts and neurotization
anatomy and basis science
- differnce between preganlionic and postganglionic avulsions/ruptures - with preganglionic lesion the nerve keep alive because of the fact that the cell body is still alive
- roots are located in the posterior triangle of the neck between the anterior and the middle scalene, underneath the deep cervical fascia
- omohyoid subdivides the posterior cervical triangle into superior/occipital and inferior/subclavian triangles
- upper and middle trunk - superior/occipital
- lower trunk - inferior/subclavian
- most common are the roots C5-Th1 - about 71%
- upper trunk - C5-C6
- middle trunk - C7
- lower trunk - C8-Th1
- each trunk divides into anterior and posterior divisions
- coalesce into the posterior, medial and lateral cord
- cords branches into peripheral nerves
- injuries are classified based on the anatomic level
- roots and trunks are superior to the clavicle
- divisions are deep under the clavicle
- cords and branches are distal to the clavicle
- anatomy is very important to rule out the height of BPI lesion
epidemiology
- incidence about 0,6 per 100.000 persons
- usually high energy traumata or penetrating injuries (stap wound or gun shots)
- men women = 9:1
- age about 30
- most common cause are traffic accidents - mototrcycle, all-terrain vehicle or snowmobile, penetrating trauma or sudden impact of the shoulder girdle
- pull to the upper extremity - upper BPI
- sudden hyperabduction - lower BPI
pathophysiology of nerve injury and nerve repair
seddon classification
- conduction block - neuroproxia
- lesion in continuity - axonotmesis
- complete division - neurotmesis
sunderland classification
- expanded for axonotmesis - which part is transected
- sunderland’s classification directly correlates with the histologic findings
- injured nerve undergo morphological changes decribed by August Waller - called Wallerian degeneration of the nerve
- begins 24 to 48h after the injury - distinctive loss of fascicular elements are lossed with a microscope
- process (degradation of axoplasm and axolemma) is fascilitated by a calcium influx accompanied by proteases at the time of the injury
- Myelin is phagocytosed
- Schwann cell’s de-differentiate into Büngner’s bands that align along the basal lamina
- bands span the gap between the injured nerve ends to help organize the reperative response and outgrowth of the healthy end
- this response is further mediated by a host of inflammatory cytokines which recruit macrophages to the site of the injury
- common neutrophic factors include nerve growth factor (neurotropin 3-5, epidermal growth factors, insulin-like growth factors I and II, glial-derived neurotropic factor and brain-derived neurotropic factors) - advancement of the growing cone
- neurotropism describes the ability of the regenrating growth cone to preferentially select its correct destination (motor Schwann cell tubes for motor fascicles and sensory tubes for sensory fascicles)
evaluation
- more than one associated injury
- initial evaluation of the plexus begins normally at the trauma day with triage and effective management of the severly injured patient
- mostly head injuries, shoulder girdle fracture dislocations and chest wall trauma occur most frequently
- cervical spine injuries and/or spinal cord injury also should be noted (preganglionic injury)
- vascular injury in about 20% of cases
- normally the plexus treatment is done subacutely when the injury zone has declared itself
- common injury patterns: C5-C8 (pan plexus), C5-C6 upper plexus and C5-C7 upper plexus (isolated lower plexus injuries are seldom)
- pan plexus about 40% of BPIs with combination of preganglionic and postganglionic trauma
- high likelihood of a graftable spinal nerve (usually C5) in pan plexus injury is important - because of limited intraplexal and extraplexal nerve transfers
- informations from clinical history, physical examination, electrodiagnostic studies and advanced imaging must answer the following questions
- which elements are injured and how does this effect the patiens function
- is it a nerve root avulsion, rupture or both
- what is the anticipated natural history of the neurologic deficits given from the time of the injury
History
1970 - 1980 - Millesi - first grafts for birth and traumatic injuries of the Plexus brachialis
1980 - 1990 - more diagnostic and advanced surgical techniques
2005 - nerve transfer becomes more and more important
Traction injury
caused by traction or stretch injury -
low energy cause traction and streching without avulsion or rupture - (Sunderland I) or lower degress of axonotmesis (Sunderland II) maybe ischemic injury
high-energy cause - ruptur of plexal elements (Sunderland V)
shoulder neck angle widening - mostly C5, C6 and mabe C7 are involved - have a good fixation to the bone - mostly disruption
scapulo-humeral angle is widening - mostly C8 and Th1 are involved - no good fixation to the bone - mostly avulsion injuries
most patient show a variable and mixed type of injury with avulsion and rupture or stretching
mostly accompanied injuries - the whole shoulder girdle - the chest wall - the lung - the spine - the head - 20% have vascular traum
gunshot wounds
plexal elements usually in continuity but some elements are transected
low- and high-velocitiy damage - direct damage or by second condition (shockwave only with high-velocitiy)
good oberservation - often a spontaneous recovery - if not surgical repair is required
laceration injury
sharp - with knifes or glasses
blunt - with fan, motor blade, chain saws or animal bites
immidiate surgical exploration - 30% required vascular surgery - maybe development associated hematoma, pseudoaneurysm fistula (as with gunshots or traction)
common patterns of BPI
preoperative evaluation
no further recovery - surgery should be achieved in the first 2-3 month -
preganglionic - no graft repair possible- often early surgery is necessary
each patient needs an individual approach - multidisciplinary clinic
History:
understand the mechanism of the injury - more severe trauma have a less potential of spontaneous recovery - severe pain in an anesthetic extremity could be a root avulsion
Physical examination
special documentation sheets
serial examinations over the first month may help to determine the presence or absence of ongoing nerve degeneration or prognosis for recovery
injury of rhomboid and serratus anterior indicates a proximal preganglionic nerve root avulsion
Horner Syndrome indicates a lower preganglionic low plexus injury (T1 sympathetic ganlion is closed to the T1 root)
absence of tinel sign suggests a preganglionic root avulsion
later on muscular artrophy of the paraspinal muscles indicates a preganglionic root avulsion with shifting the head to the contralateral side
postganglionic: precence of tenderness supra- and infraclaviculary region - absence of sweating and minimal preservation of movement - advancing Tinel sign is suggestive of a recovering lesion
Imaging Evaluation
normal x-rays for treatment of trauma patients - elevated diaphragma indicates a preganglionic nerve root avulsion of C3-5 - fractures of the transversal process of the spine - especially with good fixation with the nerve root (C5-C6) - rib fractures are important for later nerve transfer (10% of nerves are damaged with fractures)
later on - Myelography and CT-Myelography - in the modern times also the MRI for a lot of centres
classification of Nagano and collegues
N, normal
Al, slightly abnormal root sleeve shadow
A2, obliteration of the tip of the root sleeve with shadow of root or rootlets showing
A3, obliteration of the tip of the root sleeve with no root and rootlets shadow visible
D, defect instead of root sleeve shadow
M, traumatic meningocele
Myelography is normally performed after 3-4 weeks - blood clot wil be dissolve and the pseudomenigocele to form and visualize
MRI can see more peripheral findings
maybe a angiography and CT angiography is performed to achieve the blood supply especially for free functional muscle transfer (FFMT)
pulmonary function test
special case of diaphragma involvement and the possibility to harvest intercostal nerves - normally a good patient tolarates the four or five intercostal nerve transfers even if concomitant phrenic nerve dysfunction becomes present
electrodiagnostic evaluation
can diagnose, localize and characterize the nerve lesion and gives evidence of potential recovery
baseline 3-4 weeks after trauma to allow the complete wallarian degeneration
should include EMG and nerve conduction studies (NCS)
EMG
fibrillation at rest and absence (complete injury)
fibrillation reduced (partial injury)
nascent motor unit potentials (low in amplitude, polyphasic in configuration and of variable duration) signs of reinnervation
e.g. rhomboids, seraratus anterior and cervical spine muscle with an abnormal EMG may suggest a high proximal preganglionic injury
trapezius should be evluated for potential nerve transfer of the spinal accessory nerve
NCS are helpful for differentation of injury level
SNAP - sensory nerve action potentials - preganglionic SNAP are preserved because of the viable cell body - if postganglionic injury the SNAP will be lost. - MNAP (motor nerve action potenials) will be lost with both kinds of injury
the electrodiagnosis is repeated 2 month after the first baseline to determine changes of recovery - although there is a recovery (advancin tinel sign, presence of nascent units and the improvement of function) all findings can not necessarily eliminate the need for surgery
Indications for surgery
no hope of spontaneous recovery or for further recovery
patients with any traumatic mechanism
laceration immidiate
gunshots delayed
traction injuries normally delayed with a observation of about 2-3 month
if a patient could clearify identified with a preganglionic nerve root avulsion surgery can done earlier because there is no possibility for spontaneous recovery
every operation should be indicated by the individual situation of the patient the examinations in the context of time
contraindications for surgery
absolute contraindications are rare
stiffness, contracture, medical comorbidity, associated traumatic brain injury or spinal cord injury should be considered
no surgery to patients with a good recovery - outcomes in literature are seen to be better without surgery
C8-Th1 is a relative contraindication for surgery because the nerve cannot reach the hand - forearm nerve transfers or secondary reconstruction (tendon transfers) should be achieved
if more than one year has passed primary plexus surgery is contraindicates, maybe in special cases distal nerve transfers can be considered up to 18 month after trauma
Timing of surgery
based on three principles:
- better functional outcome in patients with spontaneous recovery
- surgical intervention for patients with no hope for spontaneous recovery
- surgical outcome is better with early performance
Immediate surgery
sharp open injury - immediate injury
blount laceration - maybe delayed within 3-4 weeks - better definition of the injury zone
occassionally the nerve surgeon could join the operation when the vascular surgeon reconstructed the vessels - than the nerve surgeon could explore the plexus in the same time for later surgery planning - sharp devisions can repair immediately, blunt devision are coapted loosely and marked with radiopaque vascular clips - than exploration 3-4 weeks later with a good surgery plan
avulsed roots can be perform immediately or at a second setting depending on the patiens condition
nerve are stretched but in continuity - this should be observed
delayed surgery
gunshot wounds and traction injury is usually observed if there is any sign of spontaneous recovery
the surgeon have to determine the probability of spontaneous recovery
root avulsions should be explored earlier
pan plexus - after 2-3 month
no suspicion of root avulsion could wait 3 to 6 month
is there a high rate of spontaneous recovery you can wait 5-6 month
no surgery after 6 month - bad outcome
intraoperative monitoring for NAPs will help to determine the grade of sponataneous recovery for intraoperative decisions
secondary reconstruction
FFMT, tendon transfers, bony or soft tissue procedures should be used for patients seen after 12 month
algorith in surgery treatment of adult BPI by Millesi
tinel consistently negative, no MUAP - supect preganglionic 5-level injury - do surgery
tinel positive but stationary, no MUAP - suspect postganglionic injury leve IV/V - do surgery
tinel positve and advancing MUAP present - suspect postganglionic injury leve II/III - continue oberservation for 4-6 weeks with reassessment
is there ongoing clincal recovery
yes - level II injury - no surgery
yes - level III - but plateaued - do surgery when recovery do not progress
no - level III injury with external or internal compression - do surgery
approach
different types - maybe 2 incisions to prevent scar forming - want to see the whole than zigzag incision from the proximal lateral border of the SCM to clavicle ongoing to the coracoid process and than through the deltapectoral groove to the medial arm
divide the m. omohyodius in the lateral neck triangle - the underlaying fat patty has to be mobilized - now the subclavian artery and vene can be seen medially -
plexus lays between the anterior and medial scalene muscle - the anterior scalene can be resected for better overview of the plexus - identify the n. phrenicus and carefully hold is medially - now the upper plexus can be seen -
superficial cervical artery over the upper trunk
transverse cervical artery over the middle trunk
the pectoralis major is mobilized medially, the pectoralis minor is divided hold proximal and distal - now the infraclavican plexus can be carefully preparated
intraoperative assessment
inspection and palpation is not as reliable as in other surgeries, intraoperative assessment is very important
using of electrodiagnosis with:
SSEP (somatosensory evoked potentials), MEP (motor evoked potentials) from the contralateral skulp to proofe nerve roots in continuitiy and NAP (nerve action potentials)
Choline acetyltransferase activity - more in motor than in sensory nerves - CAT has a good qualitiy with higher than 2000 cpm