| Sign In to gain access to subscriptions and/or personal tools. |
A Case of Brachial Amyotrophy Mimicking Rupture of the Flexor Digitorum Profundus TendonDepartment of Orthopaedic Surgery, Royal Sussex County Hospital, Eastern Road, Brighton BN2 5BE, England, UK, E-mail: bexkampa{at}doctors.org.uk
Department of Orthopaedic Surgery, Frimley Park Hospital, Portsmouth Road, Frimley, Camberley, Surrey GU16 7UJ, England, UK Dear Sir, A 58 year-old lady with no medical history of note presented with a 3-week history of spontaneous inability to actively flex the distal interphalangeal joint of her right index finger, associated with occasional intermittent aching in her forearm. Neurological examination was otherwise normal. An ultrasound scan suggested avulsion of the insertion of the flexor digitorum profundus tendon. Exploration of her index finger, however, revealed an intact, although rather lax, flexor digitorum profundus tendon. Carpal tunnel decompression revealed oedematous tissue only but more proximal exploration revealed an atrophic looking muscle belly. Despite intensive hand physiotherapy, she regained no active movement at the index finger distal interphalangeal joint. Sensory loss within the median nerve territory (thumb and index finger) subsequently developed. No neurological deficits of the radial and ulnar nerves became evident. Histology of the thickened flexor digitorum profundus tenosynovium and carpal tunnel synovium showed non-specific reactive changes only. An isolated anterior interosseous nerve palsy, only affecting flexor digitorum profundus to the index finger, was suspected. However, neurophysiological studies indicated a diagnosis of brachial amyotrophy with reduced median nerve sensory potentials both in the hand and forearm (mixed nerve), absent sensory potentials in the lateral cutaneous nerve of the forearm, as well as patchy changes of chronic denervation of the flexor digitorum profundus and flexor carpi radialis muscles. Brachial amyotrophy is a rare, but under diagnosed and potentially debilitating, neurological syndrome, also known as Parsonage–Turner syndrome, neuralgic amyotrophy, brachial plexitis, shoulder girdle neuritis and idiopathic brachial plexopathy. The estimated incidence is 1 to 2 per 100,000, with a male to female ratio of 2 to 3:1, and with a usual age of onset in the third to sixth decades (Rubin, 2001). Although the exact aetiology and pathophysiology are unclear, there is often an antecedent prodromal illness or insult (Favero et al., 1987: Tsairis et al., 1972). A hereditary form of this disorder – hereditary neuralgic amyotrophy — is also recognised (Dunn et al., 1978). The classical presentation is with sudden onset of (severe) pain, followed by gradual weakness, patchy, and often multi-focal, sensory loss and atrophy (Rubin, 2001; Tsairis et al., 1972). Symptoms most commonly occur in the proximal upper limb musculature, but may involve any distribution of the brachial plexus, or present as a mononeuropathy or mononeuritis multiplex type picture – including isolated involvement of the anterior interosseous or median nerves (Rubin, 2001). Some patients, as in our case, present with minimal, or absent, pain and relatively sudden onset of weakness, or, even, complete paralysis (Rubin, 2001). Neurophysiological assessment is key in identifying brachial amyotrophy and distinguishing it from other conditions. It is characterised by absent, or reduced sensory responses ± abnormal motor potentials (reduced compound muscle action potentials, fibrillation potentials and motor unit potential abnormalities) (Rubin, 2001; Seror, 2004). Radiological studies and laboratory tests are often helpful only in excluding other pathologies (Rubin, 2001). Treatment is supportive, including steroids, analgesia and physiotherapy (Rubin, 2001). The prognosis is good with most (approximately 90% of cases) making a near full recovery over 3 to 4 years (Tsairis et al., 1972). Favero et al. (1987) found that 64% of patients with brachial amyotrophy had an orthopaedic consultation during their acute illness. As it affects the shoulder girdle most commonly, its’ more common differential diagnoses include rotator cuff injury, myopathies, acute calcific tendonitis and adhesive capsulitis. However, it may also mimic pathology in the hand or forearm, as in this case. Our recommendation is that, when faced with an uncharacteristic history of symptoms or a triad of upper limb pain, muscular weakness and atrophy, or sensory loss, neurophysiological tests are performed to avoid missing a rare diagnosis which is best treated expectantly.
Dunn HG, Daube JR, Gomez MR Heredofamilial brachial plexus neuropathy (hereditary neuralgic amyotrophy with brachial predilection) Developmental Medicine and Child Neurology 1978 20 28 46.[Web of Science][Medline] [Order article via Infotrieve] Favero KJ, Hawkins RH, Jones MW Neuralgic amyotrophy Journal of Bone and Joint Surgery B 1987 69 195 198. Rubin DI Neuralgic amyotrophy: clinical features and diagnostic evaluation The Neurologist 2001 7 350 356.[CrossRef][Web of Science][Medline] [Order article via Infotrieve] Seror P Isolated sensory manifestations in neuralgic amyotrophy: report of eight cases Muscle and Nerve 2004 29 134 138.[CrossRef][Web of Science][Medline] [Order article via Infotrieve] Tsairis P, Dyck PJ, Mulder DW Natural history of brachial plexus neuropathy. Report on 99 patients Archives of Neurology 1972 27 109 117.
Journal of Hand Surgery (European Volume), Vol. 33, No. 1,
87-88 (2008)
|
||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 |
|
|
 |
|
Sign In to gain access to subscriptions and/or personal tools.
Top
References