Brachial plexus disorders

Dr Dinesh Khandelwal, DMAssociate Professor

Department of NeurologySMS Medical College, Jaipur

Shoulder pain-frozen shoulder, cervical spondylosis, fibromyalgia, brachial plexopathy, parkinsonism

Weakness of shoulder muscles-brachial plexopathy, cervical spondylosis, stroke, muscular dystrophy

Atrophy-sequelae of brachial plexopathy, MND, muscular dystrophy

Presenting to a neurologist

Brachial plexus anatomyDisorders

idiopathic injuryothers

Approach-clinicalelectrophysiological

Management

Brachial plexopathy

Anatomy of brachial plexus

Injury Idiopathic plexitis Thoracic outlet syndrome Metastatic brachial plexopathy Radiation plexopathy Brachial plexus nerve involvement

Disorders of brachial plexus

Idiopathic Familial

Parsonage-Turner syndrome

Unknown etiology, with unilateral/asymmetric involvement of the brachial plexus.

It occurs in all age groups but is more common between the third and seventh decade

Men are affected more often than women Antecedent events occurring days or weeks prior

to the onset have been reported in 28-83% of the cases in various series-Upper respiratory infection, flu-like illness, immunization, surgery and emotional stress have been the common triggers

No triggers can be found in half of the cases

Idiopathic brachial neuritis (IBN)

Beginning as an ache/deep burning around shoulder

Rapidly intense with burning severe pain for few days-rapid development of shoulder weakness-pain subside

Serratus anterior, deltoid, biceps, or triceps-totally or almost paralyzed

Distal muscles can also be involved

Brachial plexitis

No fever/leucocytosis/ESR Occasionally mild pleocytosis in CSF Recovery-usually complete in few months to

12 months Recurrence is rare (except in familial) EPS-early only f wave and motor axonal

after a week

Brachial plexitis..

Highly restricted form-one or two nerve of brachial plexus

Most common-isolated serratus anterior Other-suprascapular, axillary, posterior

interosseus or phrenic nerve (dyspnea/elevated one dome of diaphragm on CXR)

The pathophysiology of IBN is not fully elucidated but is believed to be an immune-mediated disorder.

Brachial plexitis..

Atrophy of muscle if any or twitchings Muscle power testing at each joint and

individual muscle testing at involved joint Sensory testing in each dermatome and

each sensory nerve Conclusion drawn from clinical testing

before proceeding for EPS (extension of clinical examination)

Clinical examination

Clinical course Movements are not painful Numbness more distally, weakness is mild,

exacerbation with neck movement EPS-CMAP, SNAP, EMG MRI- root avulsions, intrinsic and extrinsic

masses of the brachial plexus, pseudomeningoceles, post-traumatic neuromas, hematomas, fibrosis, and inflammatory plexitis such as infectious, immune mediated, radiation induced, or idiopathic

Differentiating form radiculopathy

Routine nerve conduction study-median, ulnar and radial motor sensory study

Erb’s stimulation-axillary, triceps (radial), biceps (musculocutaneous)

Medial antecubital nerve of forearm F wave, SEP Compared with other limb EMG-selecting muscles from each myotome

and each nerve, paraspinal (C5 to T1)

Electrophysiology

It range from normal to mild thickening of the plexus and hyperintensity on T2WI with or without enhancement. Fat deposition and denervation signal-intensity changes appear in the muscles of the shoulder girdle and chest in the subacute and chronic phases of brachial plexitis

MRI brachial plexus

Figure 2 MRI of the chest showing the enhanced signal intensity of the left brachial plexus (arrows).

R.H. Chabot, and P.W. Wirtz Neurology 2011;76:e76

Copyright © 2011 by AAN Enterprises, Inc.

Corticosteroids-limited data are available to support its use A study by van Eijk et al, indicates that oral prednisolone may be

an effective pain treatment for brachial neuritis. A retrospective case series of 50 treated patients compared with

203 untreated cases. Median time-for initial pain relief was 12.5 days in the treated

group compared with 20.5 days in the untreated patients. 18% of the prednisolone patients recovered strength within the

first month of treatment, with only 6.3% of the control group 12% of the patients in the prednisolone group attained a full

recovery within 1 year, while only 1% of the untreated group The authors recommended that oral prednisolone be used during

the acute phase of brachial neuritis; but, they also advised that a prospective, randomized trial be conducted to verify their results.

Physiotherapy

Treatment

Hereditary neuralgic amyotrophy (HNA) is an autosomal-dominant disorder characterized by repeated episodes of paralysis and sensory disturbances in an affected limb preceded by severe pain. HNA is genetically linked to chromosome 17q25, where mutations in the septin-9 (SEPT9) gene have been found

Clinical course is same as that of idiopathic except recurrent attacks

Hereditary Neuralgic Amyotrophy

Symptoms-Pain, paresthesias (ulnar aspect) or weakness in the upper extremity.

Severity-increase after certain activities, and worsens at the end of the day or during sleep.

Advanced cases of nTOS are characterized by objective signs of weakness of the hand, loss of dexterity of the fingers, and atrophy of the affected muscles (thenar>hypothenar).

It is commonly seen in women Often, bilateral cervical rib or enlarged down-curving C7 transverse processes,

fibrous band across the cervical rib and scalene tubercle of the first cervical rib are noted in these cases

X-rays of the chest should be performed to rule out the possibility of an infiltrative process or space-occupying mass (e.g., Pancoast tumor) compressing the brachial plexus.

MRI, especially sagittal T1WI through neurovascular bundles as well as MR angiography and MR venogram of the subclavian vessels in both neutral and abduction positions, aid in depiction of neurovascular compression, stenosis, thrombosis, and aneurysms

Neurogenic Thoracic Outlet Syndrome

Sensory : Absent or reduced amplitude (<12 μV) of the ulnar antidromic sensory nerve action potential (SNAP) or absent or reduced amplitude (<10 uV) of the medial antebrachial cutaneous nerve (MABC) antidromic SNAP, with normal amplitude of the MABC SNAP in the contralateral (unaffected) extremity.

Motor: One or more of the following should be present : (1) Absent or reduced amplitude (<5 mV) of the median nerve compound motor action potential (CMAP). (2) Absent or prolonged minimum latency (>33 msec) of the ulnar F-wave (with or without abnormalities of the median F-wave), and with normal F-waves in the contralateral (unaffected) upper extremity. (3) Needle electromyography (EMG) which shows denervation (e.g. fibrillation potentials, positive sharp waves) in atleast one muscle supplied by each of two different nerves from the lower trunk of the brachial plexus, with normal EMG of the cervical paraspinal muscles and at least one muscle supplied by a nerve from the middle or upper trunk of the brachial plexus.

In addition a) Exclusion of other focal neuropathies or polyneuropathy as a cause for the abnormalities described above and b) the normal amplitude (≥ 15 μV) of the median nerve antidromic SNAP and normal conduction velocity (≥ 50 m/s) of the ulnar motor nerve across the elbow is required.

Electrophysiological diagnosis of TOS

Conservative-modification of activities that exacerbate symptoms, education, postural exercises, physical therapy and anti-inflammatory drug therapy

An observational study of 50 patients showed that strengthening and stretching exercises reduced pain among 80% of the patients after 3 months and among 94% of patients after 6 months

A 2007 systematic review of the available literature concluded that conservative treatment appears to be effective in reducing symptoms, improving function and facilitating return to work

Treatment

Radiation -chest, neck or axillary region-upper brachial plexus involvement Factors like radiation dose (>6000 cGye) and technique for breast, lung

and lymphoma The interval from the last dose of radiation to the first symptom of plexus

disorder is usually a mean of 6 years. Presentation-Limb paresthesia, swelling, and motor weakness, pain is less

severe Mechanism-occlusion of microvasculature and direct injury MRI-thickening and diffuse enlargement of the brachial plexus without the

focal mass, but does not always differentiate metastatic and radiation injuries.[

Nerve conduction studies in the early stages may show features of demyelinating conduction blocks.

EMG-spontaneous activity in the form of myokymic discharges. Palliative management of symptoms FDG PET

Radiation-Induced Brachial Plexopathy

Trauma is one of the most common causes of brachial plexopathy. These injuries usually result from a motorcycle accident or a high-speed motor vehicle accident, fall from a significant height secondary to traction or from a direct blow

Upper brachial plexus Lower brachial plexus Pan brachial plexus Pregnaglionic-root avulsion-poor prognosis Post ganglionic-supraclavicular-more common-

worse prognosis than infraclavicular

Traumatic Brachial Plexopathy

Cleyson Mupfiga HUB117 2011

27

Brachial Plexus Injuries

Upper brachial plexus injuries: “waiter’s tip position”

Lower brachial plexus injuries: short muscles of the hand are affected > “clawhand”

Clinical examination-bulk and power of muscles, sensation testing

EPS-SNAP starts dropping in amplitude by day 7 post-injury and reaches its lowest value by day 10 or 11-distal stump degeneration time

Early-SNAP-normal-misdiagnosis of preganglionic

The SNAP is not useful for predicting recovery in brachial plexus lesions as once absent, it does not return to normal, even with regeneration

Clinical and EPS

Amplitude of the distal CMAP starts to drop by day 3 following the injury, and it reaches its lowest valve by day 7

Severity-judged by day 7 Well-preserved CMAP amplitude from a clinically

weak muscle at least 7 days after the injury suggests a neurapraxic lesion

Amplitude of the CMAP correlates well with the severity of the lesion (till re-innervation has occurred), and it can be judged by comparing the CMAP from the affected limb with that of the unaffected limb 

EPS..

formula U-A/U X 100= % of axon loss, where U = CMAP amplitude of unaffected side, A = CMAP amplitude of affected side. 50-75% indicates a moderate axon loss, >75% a severe axon loss and absent CMAP indicates no viable axons at the time of the study

EPS..

If there is no response, then regeneration has to occur by proximo-distal nerve growth as there are no surviving axons for collateral innervation. If the denervated muscle lies more than 24 inches from the site of a complete nerve injury, recovery is not possible as by the time the nerve (if at all) would reach the muscle, it would have been replaced by fibrous or fatty tissue

EPS..

Nerve growth rate is about one inch a month A progressive increase in the amplitude from

a muscle on serial studies would signify re-innervation of that muscle

Needle Electromyography (EMG) examination is required to document and record the axon loss, its proximal extent, and the completeness of the lesion, especially for proximal muscles where CMAP recording is not possible

EPS..

Needle EMG also documents the earliest sign of recovery in the form of nascent units and unstable polyphasic units.

Axon loss is objectively confirmed by the presence of fibrillation potentials, which develop about 3 weeks after the injury (in the most distal muscles

On voluntarily activating the muscle, if motor units are seen, it indicates that there are surviving axons and the lesion is partial. In such cases, the regeneration will take place by co-lateral sprouting.

EPS..

If there are no motor units and no recordable CMAP from the muscle, it indicates a functionally complete lesion, and re-innervation would happen only by nerve growth from the proximal stump, provided the nerve is in anatomical continuity

After adequate time is allowed, regeneration is detected on needle EMG by the presence of unstable polyphasic units, which suggest ongoing re-innervation

EPS..

Upper limb somatosensory-evoked potentials are useful for documenting a complete pre-ganglionic avulsion of the sensory roots

SEP

MRI findings of asymmetric thickening, T2 hyperintensity, and diffuse contrast enhancement of the injured plexus are observed.

The MRI in pre-ganglionic injuries may show root avulsion, pseudomeningocele (a tear in the meningeal sheath around the nerve roots with extravasation of the CSF in the neighboring tissue), enhancement of the root exit zone, signal-intensity changes in the spinal cord at the level of root avulsion and/or paraspinal muscles and avulsion of the spinal cord.

In post-ganglionic lesions, enhancing nodular thickening (neuroma) and hematoma in the vicinity of the plexus are common imaging findings

MRI of brachial plexus injury

More common in the elderly patients Lung and breast cancers most commonly

metastasize to brachial plexus Pain is more severe Lower plexus is more commonly involved-

direct spread, lymph node involvement MR neurography with MRI helps in

diagnosing FDG PET further help in inconclusive

conditions

Metastatic Brachial Plexopathy

Suprascapular neuropathy-upper trunk-C5,C6

Suprascapular notch (transverse scapular ligament)-Supraspinous fossa-spinoglenoid notch-infraspinous fossa

Causes-repetitive shoulder movements, positions, mass lesions

Symptoms-shoulder pain (adduction of extended arm)

Weakness of shoulder abduction and external rotation

Atrophy of supraspinatus/infraspinatus

Proximal neuropathies of shoulder

D/D Cervical radiculopathy/brachial

plexitis/rotator cuff injury EPS-NCS-normal/EMG-localized to

supraspinatus/infraspinatus muscles

Suprascapular nerve

Originate-posterior cord of brachial plexus (C5-C6)-teres minor and deltoid, sensory over shoulder

Causes-trauma, isolated brachial plexitis

EPS-CMAP of deltoid from Erb’s stimulation

EMG of deltoid and other muscles

Axillary neuropathy

Originate-lateral cord (C5-C6), biceps, brachialis and coracobrachialis muscle, lateral cut N of forearm

Causes-trauma, pressure, entrapment EPS-Erb’s to biceps, sensory-lateral

antebrachial EMG-biceps

Musculocutaneous neuropathy

Origin-direct from C5, C6, C7 roots-serratus anterior muscle-winging of scapula

Causes-brachial plexitis, trauma EPS-difficult, other studies to rule out more

wide spread lesions

Long thorecic neuropathy

THANKS