A 28-year-old woman with past medical history of idiopathic intracranial hypertension (IIH) not on treatment presented to the emergency room with a history of headache, nausea and blurry vision of 5 days duration. Her neurological exam and computed tomography of head were unremarkable. We performed a lumbar puncture (LP) to rule out IIH and her opening pressure was noted to be 10 cm of water. She subsequently developed severe back pain a few hours following LP. She had a magnetic resonance imaging (MRI) of her cervical, thoracic and lumbar spine which showed a moderately large epidural hygroma extending from the lower cervical spine to the lumbar spine (Figure 1A, 1B, 1C, 1D). She was managed conservatively with bed rest. Neurosurgery was consulted and no acute intervention has been recommended. Follow up MRI spine in 5 days showed complete resolution of epidural hygroma (Figure 2A, 2B).

Figure 1: (Few hours after Lumbar puncture).

A: T1 weighted sagittal section of thoracic spine shows compression of thecal sac by epidural hygroma which extends from C4 level to lumbar spine.

B: T1 weighted axial section of thoracic spine shows compression of thecal sac by epidural hygroma, but does not cause spinal cord compression.

C: T2 weighted sagittal section of cervical spine shows compression of thecal sac by epidural hygroma.

D: T2 weighted axial section of cervical spine shows compression of thecal sac by epidural hygroma.

Figure 2: (5 days after Lumbar puncture).

A: T1 weighted sagittal section of cervical spine shows complete resolution of epidural hygroma.

B: T1 weighted axial section of cervical spine shows complete resolution of epidural hygroma.

Spinal epidural hygroma is a very rare complication following LP. In infants, asymptomatic collection of cerebrospinal fluid (CSF) in the epidural space documented with ultrasound is common. ^{Reference Koch, Moosbrugger and Egelhoff1} Also comparing to adults, children have less fibrous stroma in epidural fat which facilitates the dissection of CSF along epidural space. ^{Reference Ng and Drake2} Very few cases have been reported in literature with adults presenting with symptomatic spinal epidural hygroma after LP. Severe progressive back pain extending beyond the site of LP should raise suspicion for epidural hygroma and needs evaluation with urgent MRI Spine. ^{Reference Kiechl-Kohlendorfer, Unsinn and Schlenck3} Most epidural hygromas present with severe pain. They resolve with conservative management and rarely need an epidural blood patch. Patients with spinal epidural abscess may have similar imaging findings but they usually present with fever, back pain and neurologic deficits.