Proposed characterization of the syndrome of epidural pneumatosis (pneumorrhachis) in patients with forceful vomiting from diabetic ketoacidosis as a clinico-radiologic pentad based on systematic literature review & an illustrative case report
Authors: Gill Inayat , Edhi Ahmed Iqbal , Cappell Mitchell S. 
Published: August 2020

Abstract

Background:
Previous literature on epidural pneumatosis (pneumorrhachis, or air in epidural cavity) associated with forceful vomiting in a patient with diabetic ketoacidosis (DKA) has consisted of individual case reports without comprehensive syndrome characterization due to syndromic rarity, with the largest previous literature review comprising 6 cases. Presumed pathophysiology is air escaping from alveolar rupture from forceful vomiting via tissue planes to cause epidural pneumatosis.

Aim:
Systematically review literature to facilitate syndromic diagnosis, evaluation, and treatment. A new illustrative case is reported.

Methods:
Systematic review of literature using 2 independent readers, 2 computerized databases, and the following medical terms/keywords: [“epidural pneumatosis” OR “pneumorrhachis”] AND [“diabetes” OR “diabetic ketoacidosis” or “DKA”]. Discrepancies between 2 readers were resolved by consensus using prospectively developed study inclusion criteria. Two readers independently abstracted case report. Prospective review protocol and patients, problems, intervene, comparison group, outcomes discussed in Methods section of paper.

Results-systematic-literature-review:
Revealed 10 previously reported cases plus 1 new case (see below) that shows this syndrome presents rather stereotypically with the tentatively proposed following pentad (% of patients fulfilling individual criterion): 1-forceful vomiting (100%), 2-during DKA (100%), 3-pneumomediastinum from forceful alveolar rupture (100%), 4-epidural pneumatosis from air escape from pneumomediastinum (100%), and 5-no complications of Boerhaave syndrome or of focal neurological deficits (100%). Pentad is pathophysiologically reasonable because forceful vomiting can cause alveolar rupture, pneumomediastinum, and air entry into epidural space.

Results-illustrative-case-report:
Epidural pneumatosis occurred in a 33-year-old-male with poorly controlled diabetes mellitus type 1 who presented with forceful vomiting while in DKA. Radiologic findings also included subcutaneous emphysema, pneumomediastinum, and small pneumothorax. The patient rapidly improved while receiving acute therapy for DKA, and was discharged after 2 hospital days.

Study limitations:
Limited number of analyzed, retrospectively reported cases. Case reports subject to reporting bias. Specificity, positive predictive value, and negative predictive value not meaningfully analyzed in this homogeneous population.

Conclusions:
Based on systematic review, syndrome is tentatively proposed as a pentad with: 1-forceful vomiting, 2-during DKA, 3- pneumomediastinum, 4-epidural pneumatosis, and 5-no complications of Boerhaave syndrome or focal neurological deficits. Proposed pentad should be prospectively tested in a larger population including patients with this versus closely related syndromes.