Pneumorrhachis

Definition

Pneumorrhachis is the presence of air within the spinal canal (either in the intra- or extradural space). It is a rare phenomenon and is often asymptomatic. This condition was first reported in 1977 by Gordon et al. who used the term “pneumomyelogram” to describe air around the dura mater spinalis and has since been described by various terms in the literature (such as intraspinal pneumocele, spinal pneumatosis, spinal emphysema, aerorachia, pneumosaccus, air myelogram, etc.). The term “pneumorrhachis” was coined by Newbold et al. in 1987 to describe air in the spinal canal. Depending on the location of air, pneumorrahachis may be extradural (epidural) or intradural (subarachnoid), the former being more common.

Etiology

Pneumorrhachis may be primary (intraspinal origin) or secondary to occurrence of air in other parts of the body. Pneumorrhachis is almost always associated with air in other body compartments and cavities. It is particularly seen in conjunction with pneumocephalus, pneumothorax, pneumomediastinum, pneumopericardium, pneumoperitonium, and subcutaneous emphysema. Distribution of air in the spinal canal may be confined to isolated cervical, thoracic, lumbar, or sacral region or may be widely spread to more than one area or even the entire spine. Localization and distribution of air depends on site, rate, and volume of air entry, capacity of intraspinal space, and patient positioning.

Pneumorrhachis may be classified into following three types, depending upon the cause:

• 1.

  Nontraumatic : caused by conditions that produce high intrathoracic pressures such as violent cough due to bronchial asthma or acute bronchitis, airway obstruction due to aspiration of foreign body, after cardiopulmonary resuscitation, inhalational drug abuse such as Ecstasy or marijuana, persistent forceful vomiting, invasive tumor progression, postradiation changes, paraparesis, and leukemia.

• 2.

  Traumatic : caused by trauma to head, neck, thorax, abdomen, pelvis, or spine.

• 3.

  Iatrogenic : caused by surgery (over head, neck, thorax, abdomen, or spine), anesthesiological procedure (spinal or epidural anesthesia), or diagnostic interventions involving lumbar puncture.