Extracranial epidural emphysema: pathway, aetiology, diagnosis and management

Abstract

ABSTRACT. Extracranial epidural emphysema is an uncommon phenomenon that refers to the presence of gas within the epidural space. As an isolated finding, it is typically benign, but it can be a secondary sign of more ominous disease processes, such as pneumothorax, pneumoperitoneum and epidural abscess. Although the phenomenon has been cited in case reports, a comprehensive review of this topic is lacking in the radiology literature. The authors' aim is to report our experience with extracranial epidural emphysema, illustrating the spectrum of its clinical presentation. We also review the aetiology, pathophysiology, diagnosis and management of extracranial epidural emphysema. Pneumorrhachis (also known as aerorachia) is a term that has been used to describe air within the spinal canal. It can be separated into two distinct entities, epidural and intradural. In general, the presence of intradural intraspinal air has been associated with significant morbidity, while the presence of epidural air is typically more benign [1]. Epidural air within the spinal canal is best descriptively termed extracranial epidural emphysema and has been described sporadically in case reports. The purpose of this pictorial review is to present a diversity of clinical scenarios that can give rise to extracranial epidural emphysema and to discuss its pathophysiology, diagnosis and management. Methods and materialsA comprehensive literature search was conducted on the MEDLINE database using PubMed. Keywords including pneumorrhachis, pneumosaccus, aerorachia, intraspinal pneumocele, pneumomyelogram, epidural emphysema and epidural pneumatosis were used in the literature search. In addition to a review of the literature, four cases of extracranial epidural emphysema collected at our institution are also reported. They illustrate the common pathways of extracranial epidural emphysema.All the clinical records were reviewed for demographic data, symptoms and duration of symptoms. The study did not require approval from the institution's Investigation Review Board. However, the Brooke Army Medical Center Department of Clinical Investigation reviewed and approved the manuscript for publication. Results Case 1A 59-year-old male complained of left flank pain. He had a non-contrast CT of the abdomen and pelvis that showed a left ureterovesical junction stone. The examination also revealed severe degenerative disc disease at L4-5 and L5-S1 disc spaces with vacuum disc phenomenon and extracranial epidural emphysema behind the L5 vertebral body (Figure 1a,b). Case 2A 20-year-old male presented with diabetic ketoacidosis and crepitus in the neck and upper chest. He had palpable crepitus over his jaw and a friction rub on cardiac examination. A CT scan of the chest showed severe pneumomediastinum tracking from the mediastinum into the soft tissues of the neck, anterior and posterior chest wall with pneumopericardium and extracranial epidural emphysema (Figure 2a,b). Case 3A 49-year-old male with Crohn's disease presented with abdominal pain and distensi...

Extracranial epidural emphysema associated with pneumomediastinum and subcutaneous emphysema in a greyhound

“…In human medicine, the most common cause for development of extracranial epidural emphysema is thought to be rupture of a vacuum disc. The presence of gas within an intervertebral disc is common and occurs in 2.0–3.2 per cent of the standard human population, but may be seen in up to 20.8 per cent in elderly populations 2. Another common scenario is high intrathoracic pressure and barotrauma3–5 in the setting of pneumomediastinum or pneumothorax and air tracking along the fascial planes through the neuroforamina and into the epidural space 14.…”

“…Presence of air in the vertebral canal has been described under various terms such as pneumorrhachis, aerorachia, intraspinal pneumocoele, pneumomyelogram, spinal emphysema and epidural or subarachnoid pneumatosis 1 2. As the spinal dura mater does not serve as a periosteum, there are multiple different pathways by which air can enter the spinal epidural space.…”

“…In human radiology, extracranial epidural emphysema is a rare finding, typically benign, but can be secondary to severe pathology, including life‐threatening conditions 1 2. Different pathways of air entry into the spinal canal discussed in the human literature include vacuum phenomenon of intervertebral discs, entry of air from paraspinal tissues through the intervertebral foramina, direct introduction of air via a spinal procedure (surgery, cerebrospinal fluid tap) or open fracture, and dissemination of air via communication of the venous plexus with the pelvic venous system 3–11…”

A Case of Spontaneous Extracranial Epidural Emphysema

“…This was a case of a rare occurrence of spontaneous extracranial epidural emphysema associated with esophageal cancer. Generally, extracranial epidural emphysema is localization of air within the extracranial epidural space [ 1 , 2 ], which is distinct from cranial epidural emphysema that can be seen in penetrating head injuries or infections with gas-forming organisms such as clostridia. It is important to realize that the epidural space surrounding the brain and the epidural space surrounding the spinal cord are two distinct spaces that do not communicate with each other.…”

“…However, the presence of air in the extracranial epidural space is not commonly encountered. When encountered, it is usually seen in patients with spine surgeries, spinal tap or trauma [ 1 ]. The presence of spontaneous extracranial emphysema is a rare radiological finding, rarely reported in case reports [ 2 ].…”