Case Report

Idiopathic Brachial Neuritis Mimics Cervical Radiculopathy: A Case Report


  • Evrim Karadağ Saygı
  • Canan Şanal Toprak
  • Koza Çubukçu
  • Hakan Gündüz

Received Date: 29.04.2016 Accepted Date: 09.08.2016 Meandros Med Dent J 2020;21(1):83-88

Idiopathic brachial neuritis (IBN) is an uncommon clinical disorder with an onset of acute, aching shoulder pain, followed by progressive muscle weakness and atrophy of the shoulder girdle and upper extremity. A 47-year-old male patient presented with an onset of acute left shoulder pain, which has lasted for two months. On physical examination, he also demonstrated a severe upper extremity weakness. Imaging tests showed a compression at C6 level on the left foraminal canal. According to these findings, the primary diagnosis was cervical radiculopathy, which may have required surgical intervention. However, the detailed history of pain, physical examination findings and electroneuromyography (ENMG) results were consistent with IBN that has a slow but progressive recovery with conservative treatment. Although a detailed history and physical examination are key points in the diagnosis of IBN, ENMG is the most helpful method for early and correct diagnosis that helps avoid unnecessary interventions.

Keywords: Brachial neuritis, cervical radiculopathy, electrophysiology


Idiopathic brachial neuritis (IBN) is a peripheral neuropathy, with an unknown etiology, which mostly affects the upper trunk of brachial plexus, although focal involvement of individual nerves is also seen. Although there is no consensus about the most frequently affected nerve, suprascapular, long thoracic, radial, phrenic and axillary nerves were reported as commonly involved nerves in literature (1,2). This clinical entity is also known as brachial neuralgia, brachial plexus neuropathy, neuralgic amyotrophy, acute brachial radiculitis and Parsonage-Turner syndrome. It has a reported incidence of 1/1000/year (3). It is 30-50 times higher than previously thought because of the expanding clinical awareness of IBN (3). This syndrome usually affects adults between ages 20-60. Typical clinical course starts with unilateral shoulder pain followed by an augmented response to painful stimuli. Motor weakness develops approximately within days to 2 weeks and may be seen in an irregular distribution due to patchy involvement of brachial neuritis (1,4). Although detailed physical examination and considering IBN in differential diagnosis are the key points, electroneuromyography (ENMG) is the most helpful study in diagnosis.

Case Report

Informed consent statement was obtained from the patient for this study. A 47-years-old male patient presented with an acute onset left shoulder and arm pain which has been lasting for two months. On physical examination, manual muscle testing of supraspinatus, infraspinatus, deltoid, biceps and triceps on the left side were graded 1/5. Sensory deficit was not detected. Left brachioradialis and biceps deep tendon reflexes were diminished. There was no restriction in the passive range of motion of left shoulder however pain was exacerbated with the shoulder movement. Shoulder pain was present but decreased as compared his initial severe pain. Past medical history was unremarkable. His laboratory findings like erythrocyte sedimentation rate, complete blood count and routine biochemical examinations were within normal limits. C-reactive protein and rheumatoid factor were negative.

In cervical magnetic resonance imaging (MRI) on level C5-6 there was left posterolateral-foraminal disc herniation and probable compression on left C6 root (Figure 1, 2). In the electrophysiological study bilateral median, ulnar and radial nerve conduction studies were normal, but on the left side lateral antebrachial sensory nerve action potentials were absent (Table 1). In needle electromyography (EMG), there were abnormal findings in spontaneous action potentials in deltoid, biceps, triceps, brachioradialis and 1st dorsal interosseous muscles bilaterally. Although both extremities were affected, pathological findings were more prominent on the left side. On left deltoid muscle motor unit action potentials were absent. Cervical paraspinal muscle studies were within normal limits (Table 2).

The patient was diagnosed as IBN by evaluating the type of pain, diffuse muscle weakness and ENMG results. Gabapentin and non-steroidal anti-inflammatory drugs were prescribed to reduce inflammation of brachial nerves and pain, as recommended in literature (2,5). Physical therapy programme was designed. After two months his pain was relieved and muscle weakness was improved slightly. When ENMG was repeated after three months, partial regeneration findings were evident. On clinical examination pain and muscle weakness were detected also on the asymptomatic side.


This patient was admitted to physical medicine and rehabilitation clinic with an acute severe left shoulder pain, which decreased in the last weeks. He also complained about progressive upper extremity weakness, demonstrated on physical examination.

In this case, primary diagnosis was cervical radiculopathy (CR). Compression in C6 level in MRI, on the left foraminal canal was evident. However, the patients’ symptoms were also consistent with typical clinical course of IBN. Therefore, a differential diagnosis between CR and IBN was planned to avoid unnecessary interventions, because of their similar features, particularly at the time of onset.

CR and IBN are characterized by pain in shoulder, and upper extremity. Although CR generally has a gradual onset, IBN has a sudden onset of severe pain. Progression of upper extremity weakness is generally related to increasing pain in CR patients, while upper extremity weakness related to IBN typically develops as the pain decreases. While neck movements generally aggravate the symptoms of CR, the symptoms of IBN worsen with shoulder movement (6). In this case, presence of the pain exacerbated by shoulder movement and also upper extremity weakness related to reducing pain were consistent with IBN.

The prominent symptom is the pain in shoulder girdle. Pain is severe, burning and sharp; it radiates up to neck, down to forearm on the lateral side. Pain is acute and night pain is prominent (7,8). It may last from a couple of hours to 2-3 weeks.

Muscle weakness and pain symptoms may be seen together, but shoulder pain followed by patchy muscle weakness is a more common profile (4,9). In the series of van Alfen et al. (8), which consists of 246 cases, weakness developed within 24 hours in 33%, 1-7 days in 40%, 1-2 weeks in 14% cases. Weakness does not always follow the same route that pain follows. Atrophy may develop in the affected muscles (10).

Mild and patchiness sensory symptoms occur in a majority of patients on careful examination, frequently in the distribution of the lateral cutaneous antebrachial nerve. Sensory or motor symptoms may not match the distribution of pain and may not be noticed by patient because of the severe pain; it is very important clue for diagnosis of IBN (5,11). In this case, there was no clinically confirmed sensory loss, even though antebrachial sensory action potentials were absent in the ENMG study, and this was considered as an evidence of IBN.

In the cases of IBN, laboratory findings are within normal range. Complete blood count, sedimentation rate, serum electrolytes, liver enzymes, the chemical analysis of urine samples and immunological studies are within normal limits. (4,9). In this case laboratory findings proved no abnormalities, as mentioned. However, laboratory findings are also expected within normal range in CR patients and don’t have a role to differentiate IBN from CR.

When considering the differential diagnosis, musculoskeletal disorders of shoulder, CR, poliomyelitis, amyotrophic lateral sclerosis, herpes zoster, tumors of spinal cord or brachial plexus, posterior interosseous nerve palsy, traumatic or compressive nerve injuries should be considered (12,13).

In this case ENMG study was planned to make the differential diagnosis between CR and IBN.

ENMG can localize the lesion and help confirm the diagnosis (4,9,14). Nerve conduction studies of the motor nerves are generally within normal limits. The amplitude of sensory nerve potentials may be smaller than expected. Needle EMG is the most helpful study in this diagnosis. In the needle EMG of proximal muscles with weakness and atrophy, fibrillation and positive sharp waves are evident (6). Paraspinal studies are usually in normal limits. It usually seems unilateral but about a third of these patients have bilateral involvement with an asymmetrical severity. Hence, even though the patient may complain of unilaterally clinical symptoms, bilaterally ENMG findings may be seen (15).

According to literature it is said that electrophysiological findings of C6 radiculopathies are less typical and specific compared to other radiculopathies on different levels. C6 radiculopathies may have electrophysiological symptoms of C5 and/or C7 radiculopathies (9). This case had diffused proximal muscle weakness and showed denervation findings on EMG studies. These symptoms may have been due to C6 radiculopathy. However, it was unlikely to explain the fibrillation and positive sharp waves of first dorsal interosseous muscle, which is innervated by C8-T1 roots. Patchy distribution findings of paresis supported diagnosis of IBN. On the other hand, this case had also unilaterally clinical symptoms but bilaterally ENMG findings that were consistent with bilateral IBN. Lateral antebrachial cutaneous sensory responses were absent, and this is a symptom of upper trunk brachial plexopathy. Paraspinal EMG results were normal as would be expected with IBN. When all of the results above were considered these led us to the diagnosis of IBN.

IBN is a benign disorder with good prognosis. Approximately 80%-90% of the patients recover after 2-3 years, but 35%-70% may remain with residual paresis and exercise intolerance (16,17). Complete recovery of muscle strength and functioning is common. However, duration of recovery alters from one patient to the next. It may go from 1 month up to 3 years. Sensory and motor improvements occur at the same rate. If pain is intense and muscle weakness is severe, healing process takes more time. If there is more than one nerve involved, recovery is expected to be slower. In upper trunks lesions, prognosis is better (10,16). Exceptionally spontaneous recovery does not take place and the patient may require surgical intervention.

To conclude, incidence of IBN is not as rare as previously thought. It needs to be considered as a differential diagnosis in patients who complain about acute intense shoulder pain. A detailed history and physical examination are required for diagnosis. CR should be excluded to avoid unnecessary and inappropriate interventions. In order to differentiate IBN from CR, detailed ENMG studies on both affected and unaffected (contra-lateral) sides may help clinicians for early diagnosis.


Informed Consent: Informed consent statement was obtained from the patient for this study.

Peer-review: Internally peer-reviewed.

Authorship Contributions

Concept: E.K.S., H.G., Design: E.K.S., K.Ç., Data Collection or Processing: C.Ş.T., K.Ç., E.K.S., Analysis or Interpretation: H.G., C.Ş.T., E.K.S., K.Ç., Literature Search: H.G., C.Ş.T., E.K.S., K.Ç., Writing: H.G., C.Ş.T., E.K.S., K.Ç.

Conflict of Interest: No conflict of interest was declared by the authors.

Financial Disclosure: The authors declared that this study received no financial support.


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