A painful shoulder after a seizureBMJ 2019; 366 doi: https://doi.org/10.1136/bmj.l4511 (Published 08 August 2019) Cite this as: BMJ 2019;366:l4511
All rapid responses
We read our colleagues’ spot diagnosis article with great interest as well as the rapid response by our Australian colleague. Further to his response we wished to submit our own comments.
The article recommends a lateral or modified axillary view to aid diagnosis of posterior shoulder dislocations, however we conducted a large-scale review of missed posterior dislocations at a major trauma centre in London and found that a lateral view is of far inferior diagnostic benefit compared with a modified axial view and can even be falsely reassuring. Our findings, as well as an extensive literature review, led us to recommend the anteroposterior (AP) and modified axillary view only. This recommendation is supported by a previous retrospective review (Neep MJ et al. 2011), which found that almost 10% of examinations would have been incorrectly reported as normal if AP and lateral views were performed without a modified axial view and, furthermore, lateral views did not demonstrate anything which was not shown on modified axial views. We add that, in cases of diagnostic uncertainty, an urgent CT scan should be performed.
The authors go on to recommend immobilisation in a sling post reduction. While they do not clarify, it would be sensible to assume they mean a simple broad arm sling. This is not appropriate in the case of a posterior dislocation, as the internal rotation of the shoulder in such a sling is a position of instability and often leads to recurrent dislocation. To avoid this, the shoulder should be maintained in either a neutral or externally rotated position with an appropriate brace. On a related note, the ‘lightbulb sign’ on an AP view is no longer considered pathognomonic of posterior dislocation because, when a standard sling is applied at initial presentation, this internally rotated position is often radiologically indistinguishable from that associated with posterior dislocation resembling a lightbulb.
Our review of the radiological diagnosis of posterior shoulder dislocations as well as the specifics of an imaging protocol for shoulder trauma which we have introduced at our institution is currently under review for publication with BMJ Open Quality. Should you wish for further details we would be happy to provide them.
Competing interests: No competing interests
I noted the purpose of the article is to demonstrate the "lightbulb sign" in a patient with posterior dislocation of the shoulder, and to consider the possibility of posterior shoulder dislocation in a patient with history of new-onset shoulder with a background of seizure.
However it may interest readers that the lightbulb sign in the example provided by the authors in this article is not as obvious as images available on other websites (for example ref 1) as I suspect that there is a superimposed reverse Hill-Sachs impaction depression lesion on the anteriomedial humeral head.
If this is true then the history provided that "no history of seizures" is suspect as a reverse Hill-Sachs lesion from posterior dislocation implies at least one previous episode of posterior dislocation and often a reflection of chronic recurrence of this uncommon traumatic condition typically caused by generalised tonic-clonic seizure or electrocution.
Some care should be taken when discussing post-reduction management of a posterior-dislocated shoulder; "immobilisation in a sling" for 2 weeks may be a common management for shoulder dislocation but not always the best treatment for someone with a posterior shoulder dislocation. In cases when the shoulder is swollen and unstable, placing the shoulder in a position internal rotation, particularly with a large reverse Hill-Sachs lesion, may predispose the patient to have a recurrence of posterior dislocation.
There is some merit in placing the patient's affected arm (and shoulder) in a neutral position with a shoulder immobiliser and abduction pillow post-reduction of posterior shoulder dislocation with a large reverse Hill-Sachs lesion. Patients should be carefully instructed about how to maintain personal hygiene if this treatment is needed.
While I understand the authors are orthopaedic clinicians, I am also concerned that the management of the adult patient's first seizure was not adequate addressed in the article. The diagnosis of first seizures and differentiation from their “mimics” in adults is frequently poorly performed, much in part due to poor history-taking and clarification. "Following a first seizure of any kind, all patients should be referred to a specialist for investigation"; "after a first seizure, further seizures (that is, epilepsy) occur in between 6% and 82% of patients" (ref 2).
While many will expect emergency clinicians to organise appropriate specialist follow-up for the management of an adult with an unexplained seizure, sometimes in examples where an orthopaedic injury (fracture and/or dislocation) is identified arising from the seizure, then the orthopaedic team may be the only specialist service involved in the episodic care of such patients.
It is important for all clinicians to be mindful of the holistic care of a patient; if a condition is not within their scope of practice to organise or transfer care to another clinician with the appropriate expertise.
An unexplained first seizure in a 25 year-old man may result in significant ramifications in medical, functional (eg driving) and occupational (eg operating heavy machinery) aspects of his life, with possible medico-legal ethical dilemma for his treating doctors (ref 3).
Competing interests: No competing interests