Original Editors - Jesse Demeester
Parsonage–Turner syndrome (PTS) is the term used to describe a neuritis involving the brachial plexus, and is also referred to as idiopathic brachial plexopathy or neuralgic amyotrophy. It may present with symptoms of an isolated peripheral nerve lesion, although the pathology is thought to lie more proximally. PTS is a rare disorder that generally involves one upper limb, mostly the axillary nerve, the upper trunk of the brachial plexus, the suprascapular nerve, and the long thoracic nerve are affected.
Clinically Relevant Anatomy
The brachial plexus is a network of nerve fibres formed by the ventral branch of the lower four cervical nerve roots (C5-C8) and first thoracic nerve root (T1). It passes through the cervico-axillary canal in the neck, over the first rib, and into the axilla where it innervates the upper extremity (the brachium, antebrachium, and hand) as well as some muscles of the neck and shoulder.
The incidence of neuralgic amyotrophy is approximately 2-3 per 100,000 persons per year. It is more prevalent in men than in women (approximately 3:2), with the highest incidence occurring between the third and seventh decades. PTS occurs with an overall reported incidence of 1.64 cases per 100,000 persons per year. There does not appear to be a prevalence for hand dominance nor is there a general trend towards development of the condition more on the left versus the right. The etiology of the syndrome is unclear, being reported in various clinical situations including post-operatively, post-infectiously, post-traumatically and post-vaccination.
Initially, a sudden, constant, severe shoulder girdle pain develops. This pain may extend to the trapezius ridge, upper arm, forearm, and hand. The pain is not positional and usually worse at night and may be associated with awakenings from sleep. The pain is often described as a severe ache or throbbing radiating from the shoulder distally down the arm or proximally into the neck. The duration of pain is almost always self-limiting, lasting 1 to 2 weeks but on rare occasions can persist for longer periods of time.
Other symptoms are:
- Sensory deﬁcits (not in all the patients)
- Muscle weakness
- Muscle-atrophy (within a month)
Scapular winging may be seen when there is involvement of the scapulothoracic nerve innervating the serratus anterior muscle. The weakness may be limited to muscles innervated by a single peripheral nerve or any combination of peripheral nerves or the brachial plexus.
On EMG study a widespread denervation is seen of the affected muscles.
MRI may show a nonspecific inflammatory response in the brachial plexus in case of PTS.
In the beginning, the pain is situated around the shoulder girdle. It can present similar to numerous other shoulder problems, such as:
Weakness of distal muscles can also occur, again presenting similar to other shoulder conditions, such as:
- Discogenic nerve root compression
- Tumors of the spinal cord
- Thoracic outlet syndrome (TOS)
- Cervical artery dissection
- Disuse atrophy of shoulder girdle muscles
- Quadralateral space syndrome
- Other entrapment syndromes around shoulder
The characteristic pattern of pain followed by profound weakness are generally the clues to the diagnosis of Parsonage– Turner syndrome with confirmation being sought by electromyography. This pain is often described as a severe ache or throbbing radiating from the shoulder distally down the arm or proximally into the neck Because of the often atypical distribution, EMG- studies need to be extremely detail- oriented in the systematic approach to testing specific muscles of the upper limb. Testing of muscles that are not routinely examined during EMG studies should be interrogated by needle EMG even when they appear to be clinically asymptomatic. Because Parsonage – Turner Syndrome is an axonal disorder commonly affecting proximal muscles of the upper limb, the motor and sensory nerve conduction velocities and distal latencies routinely tested on the distal upper limb are usually normal.
Clinical examination confirmed paralysis of flexor pollicis longus (FPL) and flexor digitorum profundus (FDP) of his index finger (4/5 weakness, Medical Research Council grade)
Physical examination of the muscles is essential for physicians to determine the presence and extent of muscle weakness in patients suspected of having Parsonage-Turner Syndrome.
Personage-Turner syndrome will lead to:
- Muscle bulk/tone: atrophy of supraspinatus, infraspinatus, deltoid, biceps, trapezius, serratus anterior, pronator teres, teres minor.
- Muscle strength
o Weakness of supraspinatus, infraspinatus, biceps, brachioradialis, pronator teres, trapezius, serratus anterior, pronator teres, teres minor.
o Normal strength of rhomboids, triceps, wrist and hand muscles
- Sensation: numbness over lateral arm, forearm and anatomic snuffbox
- Reflexes: absent biceps and brachioradialis .
In the first few weeks it is appropriate to give pain management with opiates, NSAIDS and neuroleptics. Acupuncture and transcutaneous electrical nerve stimulation (TENS) is also given in the first few weeks. Oral steroids have been recommended by some but the literature for this efficacy is poor. In an recent study immunotherapy was the form of treatment for this syndrome. At the end of this study, the conclusion was that immunotherapy causes an improvement of neurological symptoms and impairments. In cases with a cervical spine pathology, a cervical epidural may be helpful to distinguish between pain due to a cervical radiculopathy and Parsonage – Turner Syndrome. Antiviral medications may also help and this in cases presenting with a classic shingles rash.
Physical Therapy Management
In addition to medication therapy patients may be referred for physical therapy. During physical therapy the therapist focuses on patient education, upper-extremity ROM, strengthening exercises to maintain periscapular motion and modalities for adjunct pain relief. Physical therapy plays an important role in the treatment of this condition. Modalities such as TENS can help in pain management. The timing and the role of strengthening exercises are dependent on the degree of muscle denervation, the degree of weakness, and the degree of altered biomechanics and to the premorbid functional level of activity for that patient.
Range of motion exercises, which are clearly important and dependent on the muscles involved, may require the assistance of a physical or occupational therapist. Strengthening exercises are not indicated in completely denervated muscles for obvious reasons, when there is no innervation, voluntary movement isn’t possible so resistance training is impossible. When there isn’t total denervation, strengthening of the rotator cuff, other muscles of the upper limb or scapular stabilisation be indicated but depends on which nerve or part of the brachial plexus is affected. Resistance exercise must be adjusted to the patients local exercise capacity and level of pain.
The role of electrical stimulation (ES) is still controversial but should be considered especially when the denervated state is prolonged, i.e., greater than 4 months. ES can be a useful procedure for preservation or restoring the normal properties of the denervated muscles if an appropriate stimulation pattern is chosen. Optimal time to start with ES is as soon as possible after muscle nerve injury, the longer the interval between onset of denervation and the start of stimulation the less the recovery. ES will not effectively hinder the regeneration of the axon or the reinnervation of the muscle and marks an increase in muscle mass and quality.
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