Two cases of benign pneumomediastinum in patients with psychosis who had been restrained in police custody

To the Editor

We report two patients presenting with acute psychosis and pneumomediastinum after having been restrained in police custody.

Case 1

A 20-year-old male cannabis user presented with psychosis, aggressive behaviour and agitation requiring restraint while in police custody. Physical examination and laboratory tests were unremarkable, with the exception of an elevated creatinine kinase (CK) and lactate dehydrogenase (LDH). Computed tomography (CT) of the brain revealed extracranial neck gas associated with the jugular foramina and base of skull. Subsequent neck and chest X-rays revealed pneumomediastinum (Figure 1). The patient was stable, managed conservatively with intravenous fluids and transferred to the psychiatric ward for management of substance-induced psychosis.

Figure 1.

(A) CT of the brain: extracranial gas within the ‘danger space’, a potential space located posterior to the retropharyngeal space (arrow). (B) Lateral neck X-ray: gas extending superiorly into the neck within the prevertebral space (arrow). (C) Chest X-ray: mediastinal gas in the upper thorax and alongside the descending aorta (arrows), as well as soft tissue gas extending laterally to the axillae.

Case 2

A 36-year-old male presented with an acute confusional state and bizarre behaviour after 1 week in prison on a background of amphetamine, benzodiazepine and opioid abuse. Physical examination was unremarkable. Laboratory tests revealed a neutrophilia and acute kidney injury. He was treated with ceftriaxone, acyclovir, haloperidol and intravenous fluids. While CT of the brain was unremarkable, CT of the chest revealed pneumomediastinum and extensive subcutaneous emphysema (Figure 2).

Figure 2.

Extensive subcutaneous emphysema and pneumomediastinum on chest CT (A) at the level of the thoracic inlet and, at the mid-thorax, (B) at the level of the main pulmonary artery.

Pneumomediastinum commonly occurs from a pulmonary source, secondary to increased alveolar pressure (e.g. mechanical ventilation, extreme vomiting/coughing or valsalva manoeuvre), reduced interstitial pulmonary pressure (e.g. cannabis use) and/or parenchymal disease (e.g. emphysema or malignancy) (Kouritas et al., 2015). A ruptured alveolus allows gas to track along the peribronchovascular fascial sheath to the mediastinum, which communicates with vascular sheaths within the neck and other soft tissue planes (Kouritas et al., 2015). Other, more serious causes include oesophageal rupture, penetrating trauma or infection with gas-producing organisms.

Spontaneous pneumomediastinum lacks a clear precipitant and is associated with inhalation drug use or valsalva manoeuvre. It is commoner than mediastinal organ injury and rarely clinically significant in the absence of symptoms, requiring only observation and analgesia (Kouritas et al., 2015). To our knowledge, these are the first cases associated with physical restraint in police custody, without a traumatic mechanism. A case has been reported involving a 25-year-old male with a history of substance abuse and psychosis who was restrained by police during an agitated delirium (Aberegg et al., 2014). His pneumomediastinum, however, was secondary to a taser dart injury to the larynx and valsalva manoeuvre during restraint. Indeed, it has been shown that pneumomediastinum can be induced by performing valsalva manoeuvre after deliberate insertion of sharp objects into soft tissues of the oropharyngeal cavity (Lopez-Pelaez et al., 2001).

Spontaneous pneumomediastinum may occur in psychotic patients who have been restrained, likely secondary to valsalva manoeuvre. It has a benign clinical course, requires conservative medical management and should not delay psychiatric care.