Introduction Brachial Neuritis also called as neuralgic amyotrophy is an idiopathic condition which involves the brachial plexus. It usually affects young to middle aged subjects. Its classical presentation involves painful progressive asymmetrical upper limb weakness with sensory abnormalities. Herein we present a rare form of brachial neuritis which started of after endurance exercise complicated by type 2 respiratory failure due to diaphragmatic weakness.
Case Presentation This 55-year-old man presented with rapid onset interscapular pain radiating to both shoulders after strenuous endurance exercise on an exercise bike. He complained of breathlessness associated with the pain, on lying down. He was admitted to the acute respiratory ward for assessment. His worsened steadily and was not able to lie flat. He was unable to lift his arms above his shoulders and he described severe radicular in both arms. His Vital capacity was 1.6 liter on standing and 0.9 liter on lying flat (figure 1). Oxygen saturation was normal upright but dropped in the horizontal position, with significant hypoxia and mild acute carbon dioxide retention.
Nerve conduction studies showed reduced median compound muscle action potentials and reduced median and ulnar sensory action potentials bilaterally. Needle EMG showed widespread features of denervation in keeping with bilateral brachial plexus involvement.
Management and Progress He was treated with two courses of Methyl prednisolone after which his symptoms started to plateau. He was still however unable to lie flat for an MRI scan of the brachial plexus.
Discussion Neuralgic amyotrophy or Brachial neuritis is a distinct condition associated with acute onset shoulder pain, weakness and sensory symptoms. This condition was first described in 1896 in a man with bilateral shoulder weakness with winging of scapula. However, the first and most descriptive paper was from Parsonage and Turner in 1948 were they described 136 cases with a new name called the neuralgic amyotrophy the shoulder girdle syndrome. There are several conditions which were associated with brachial plexopathy. Classical Neuralgic amyotrophy or Brachial neuritis is a type of brachial plexopathy which is rare and idiopathic. Here we describe a very rare sub-type with diaphragmatic paralysis. A literature search revealed up to 70 similar case reports with diaphragmatic involvement. Clinically most of the cases had been described as our patient's presentation with some variations. Most interestingly only a single report, to our knowledge, described onset after exertion, as in our patient. Use of lying and standing vital capacity had been one of the useful investigations which helped in identifying the diaphragmatic failure. The neurophysiology, chest x ray and neuroradiological investigations may help in diagnosing the condition hence high index of suspicion is important. Our patient stopped deteriorating after 2nd course of methyl prednisolone, which may suggest an effect on corticosteroids. Generally long-term functional outcome of brachial neuritis is favourable. Recovery of diaphragm paralysis is largely unknown due to its rarity although diaphragmatic placation ids currently being considered in our patient, in view of absence of further recovery.
Conclusion We pesent a rare form of Brachial neuritis or Neuralgic amyotrophy with phrenic nerve palsy which might be difficult to identify in clinical practice. Vital capacity in lying and standing positions are required for diagnosis and a high index of suspicion is required for the examining neurologist, often having to see such atypical presentations on respiratory or general medical wards. Appropriate investigations are helpful, but history and clinical examination remain essential to avoid missing this rare but important and potentially life-threatening, but fortunately reversible/treatable disorder, for which steroids may have a beneficial role, as well as surgical intervention such as diaphragmatic plication.