What happens in the interscalene space
The brachial plexus and subclavian artery pass from the neck to the axilla through several narrow points. The first of these is a triangular gap between the anterior and middle scalene muscles and the first rib. If the anterior scalene muscle is thickened, spasmed, or has an atypical attachment, the gap narrows. The lower trunks of the plexus, which are responsible for the inner surface of the forearm and the muscles of the hand, are most affected. Hence the characteristic combination: pain in the neck, numbness of the little finger and weakness of small finger movements.
- Compression occurs between the scalene muscles and the first rib
- The lower trunks of the brachial plexus are most often affected
- The subclavian artery may also be compressed
- Less commonly - subclavian vein
- Symptoms worsen when raising the arm
Causes and risk factors
The most common cause is anatomical: an additional cervical rib or a dense fibrous cord running to the first rib. Then acquired factors come into play: whiplash injury to the neck during sudden braking, stooped posture with the head pushed forward and shoulders down, chronic overload when working with raised arms. A bag or backpack on one shoulder, prolonged work at the computer and sleeping in an uncomfortable position maintain the spasm. In women, the syndrome is more common, and the first complaints usually appear in young and middle age.
- Accessory cervical rib or fibrous cord
- Neck injury, including whiplash
- Slouching and forward head
- Working with raised hands: painters, hairdressers, athletes
- Carrying heavy weights on one shoulder
- Previous fracture of the clavicle or first rib
Symptoms
The pain is usually aching, localized in the side of the neck, shoulder girdle and shoulder blade, radiating along the inside of the shoulder and forearm to the little finger and ring finger. Often there is a feeling of crawling sensations and numbness, which intensifies at night and when the hand is raised up - for example, when a person holds on to a handrail or dries his hair. With the vascular variant, the hand quickly gets tired, turns pale and freezes, with the venous variant it swells and turns blue. Sometimes a weak grip and clumsiness of the fingers are noted.
- Pain in the neck, shoulder and inner edge of the arm
- Numbness and tingling in the little finger and ring finger
- Increased complaints when raising the arm and turning the head
- Weakness of the hand, objects fall out of the hands
- Coldness and paleness of the hand
- Swelling and cyanosis of the arm due to compression of the vein
Diagnostics
The diagnosis is primarily clinical: the doctor assesses posture, palpates the tense scalene muscle and performs provocative tests with head rotation and arm abduction, monitoring the appearance of symptoms and changes in pulse. X-ray of the cervical spine and superior aperture reveals the additional rib and the consequences of fractures. ENMG helps to confirm damage to the lower trunks of the plexus and exclude tunnel syndromes. Dopplerography of the vessels of the arm is needed if a vascular variant is suspected, and MRI of the cervical spine is needed to exclude a disc herniation.
- Neurological examination and provocative tests
- X-ray of the cervical spine
- ENMG of the upper extremities
- Dopplerography of arteries and veins of the arm
- MRI of the cervical spine
- If necessary, CT or MR angiography
Treatment and prevention
The basis of treatment is conservative and takes time. Select a program of exercises to stretch the scalene muscles, strengthen the interscapular muscles and restore the position of the head and shoulders; classes are done daily. Soft manual techniques, massage of the collar area and physiotherapy help. Painkillers and muscle relaxants are prescribed by the doctor for a short course. For persistent pain, therapeutic blockades are used in the anterior scalene muscle, which at the same time confirm the diagnosis. Surgery—dissection of the muscle and removal of an additional rib—is discussed if treatment is ineffective for several months or if there are vascular complications.
- Daily therapeutic exercises for the neck and shoulder girdle
- Correction of posture and workplace
- Neck massage, physiotherapy
- Medicines only as prescribed by a doctor
- Blockades for persistent pain syndrome
- Refusal to carry a bag on a sore shoulder
- Surgical treatment if conservative treatment fails