Minimally Invasive Lumbar Decompression (MILD) is a common procedure for lumbar spinal stenosis. Radiolabeled contrast agent such as iohexol (omnipaque) is commonly administered for the epidurogram. Off-label use of gadolinium has been used for patients with allergic reactions to iohexol. Intrathecal injection of gadolinium into the subarachnoid space is a possible complication of an epidurogram. Gadolinium neurotoxicity can lead to encephalopathy, generalized seizures, respiratory failure and be fatal.

An 80-year-old woman with a shellfish allergy presented to ED with acute encephalopathy followed by new-onset generalized tonic-clonic seizure (GTC), who underwent MILD procedure a few hours prior. No reported complications during the procedure, however after the procedure she developed significant agitation which required analgesia. In the ED, she required intubation for airway protection. The CT of head revealed hyper-densities in the basilar cisterns, sylvain fissures, and scattered sulci, with diffuse areas of pneumocephalus. The initial concern was for a subarachnoid hemorrhage, however the pneumocephalus and recent procedure led to the confirmation that gadolinium was used. An emergent external ventricular drain (EVD) was placed to monitor intracranial pressure and for evacuation of the gadolinium. During her course in the Neuro-ICU she was mechanically ventilated, had continuous video EEG monitoring and medically managed with an antiepileptic medication.  

EVD drained cerebrospinal fluid confirmed the presence of gadolinium. The patient did not require a ventriculoperitoneal shunt. She had no evidence of ischemic stroke on brain MRI. Following successful extubation she was neurologically intact except for ataxic gait and bilateral hand tremor that resolved 2 months post admission. 

Any neurologic change following a MILD procedure performed with gadolinium should immediately raise concern for intrathecal gadolinium advancement into the intra-cranial subarachnoid space. External ventricular drain placement for CSF/gadolinium drainage, supportive medical care and time can lead to complete neurologic recovery.