A response to: Commentary on Prone Position Plexopathy during the COVID-19 pandemic

by Dominic Power, Caroline Miller, Joel O’Sullivan and Tahseen Chaudhry 
Brachial Plexus and Peripheral Nerve Injury Service, Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, UK

Corresponding author e-mail: dominic.power@uhb.nhs.uk

Published 08 June 2020

Submission in reponse to 'A Commentary on Position Plexopathy during the COVID-19 pandemic' by Tom Quick and Hazel Brown originally published in TJTO&C on 10 May 2020.

We would like to commend the authors for raising awareness of this important and debilitating complication of critical care (CC) proning for the management of COVID-19 associated respiratory failure. Prone ventilation has been shown to increase survival in patients with acute respiratory distress syndrome and has been successfully integrated into the ICU management of COVID-19 patients with resistant hypoxia.

The first peak of the UK pandemic has completed and to date more than 1,500 COVID-19 survivors have been discharged from University Hospitals Birmingham (UHB) Foundation Trust. Patients treated with prolonged intermittent prone ventilation have required prolonged periods of inpatient rehabilitation. Many patients manifest significant CC myo-neuropathy with symmetrical muscle weakness and wasting. Others demonstrate a painless motor loss in a mixed motor-sensory peripheral nerve distribution without sensory symptoms that may represent a virally mediated motor neuropathy. However, there are many cases with neuropathic pain, sensory loss and motor loss in the anatomical distribution of a component of the brachial plexus and/or peripheral nerve that most likely represent proning-associated plexopathy and peripheral nerve injury (PAP).

Low grade nerve injury has been seen infrequently to date, perhaps representing the less extensive involvement and more rapid return of function expected in such cases. The cases requiring prolonged rehabilitation have features of high grade complete axonopathy or intermediate grade (mixed axonopathy and prolonged conduction block) nerve injury. There is typically severe asymmetrical muscle wasting and paralysis, neuropathic pain and positive Tinel’s sign at the site of suspected injury. Whilst some patients present with dry skin from loss of small fibre autonomic sudomotor function, this is not a universal feature and may reflect the slow progressive nature of the compression injury mechanism with relative preservation of these fibres, as is seen in chronic severe peripheral nerve compression neuropathies.

The timing of the onset of the nerve injury and paralysis is unclear as many patients will have had more than two weeks of prone ventilation and so defining a persistent paralysis at three weeks is not as simple as the authors suggest.

A brief review of the first 15 cases of PAP assessed in the Peripheral Nerve Injury Service at UHB has identified 32 upper limb and 5 lower limb nerve injuries. There are 13 male and 2 female patients in this cohort, with 10 from BAME (Black, Asian or Ethnic Minority) backgrounds. The mean age is 54 (range 39-69). The number of co-morbidities is high with 9/15 obese, 11/15 hypertensive and 7/15 type 2 diabetic.

The upper limb injuries are 18 high grade, 11 mixed and 3 low grade (conduction block / neurapraxia). The most common site of injury is the ulnar nerve at the cubital tunnel (9/32) with 90% of injuries at this site demonstrating axonopathy. Other sites include upper trunk (2), axillary nerve (3), medial cord (4) lateral cord (3), posterior cord (2), musculocutaneous nerve (4) median nerve (1) and radial nerve (2).

In view of the high numbers of PAP patients with ulnar neuropathy, we would recommend that in the prone ventilated patient, the position of the elbow in the elevated arm should be at no more than 45 degrees of flexion rather than the 90 degrees recommended in the UK Faculty of Intensive Care Medicine guidelines1.

We would also recommend that the referral guidelines recommended by Quick and Brown are appropriate, however it should be clarified that the timing of onset of paralysis is not clear due the prolonged period of ventilation. In addition, not all patients may be suitable for transfer to another unit for evaluation due to the complex nature of the rehabilitation needs in the cases assessed to date. It may be appropriate for local orthopaedic or plastic surgeons to perform the initial clinical assessments, clinical reviews and investigations in cases where transfer is not feasible.

Reference

  1. The Faculty of Intensive Care Medicine (2019). Guidance for: Prone Positioning in Adult Critical Care. Available at: https://www.ficm.ac.uk/sites/default/files/prone_position_in_adult_critical_care_2019.pdf.