Aseptic Meningoencephalitis after Iohexol CT Myelography

Abstract

SUMMARY:We describe the case of a patient with aseptic meningoencephalitis after intrathecal iohexol injection for myelography and review the previous literature on similar cases of contrastinduced neurotoxicity.A septic meningoencephalitis is a rare complication of myelography with nonionic, iodinated, water-soluble contrast agents. We describe a case of a 69-year-old woman in whom aseptic meningoencephalitis developed after she underwent iohexol myelography. Case ReportA 69-year-old white woman underwent a technically successful outpatient CT myelogram with 10 mL of iohexol (Omnipaque 300; GE Healthcare, Cork, Ireland). The CSF was clear and colorless, and myelogram revealed degenerative osteoarthritis and severe central canal stenosis at L3-L4 secondary to short pedicles, facet and ligamentum flavum hypertrophy, and diffuse disk bulging. Approximately 12 hours after the injection, she experienced fever, headache, confusion, agitation, and aphasia. She was brought to the emergency department 20 hours after the myelogram.In the emergency department, her initial temperature was 102.5°F, and she was agitated and unable to speak, though she could shake and nod her head for "yes" or "no" responses. She complained of a severe headache and low back pain but denied incontinence or lower extremity numbness. On physical examination, she had mild symmetric lower extremity weakness that measured 4 of 5 bilaterally. Her serum white blood cell count (WBC) was 24,300 cells/L (90% neutrophils). Head CT revealed moderate to severe, chronic, smallvessel ischemic disease. Lumbar puncture and CSF analysis approximately 30 hours after the iohexol injection revealed turbid-appearing fluid with 300 white cells/L (61% polymorphonuclear cells and 1% monocytes), 5200 red cells/L, glucose level of 63 mg/dL, and elevated total protein level of 624 mg/dL. A second tube of CSF from the same lumbar puncture revealed 220 white cells/L (94% polymorphonuclear cells and 2% lymphocytes) and 1545 red cells/L. Results of CSF bacterial and cryptococcal antigens were negative. CSF culture revealed no growth at 5 days.She was initially started on intravenous ceftriaxone (2000 mg) and vancomycin (1000 mg) every 12 hours. The following day, approximately 48 hours after the myelogram, she was afebrile, and her mental status and neurologic examination had returned to near baseline with fluent speech. She was alert and oriented, with no recollection of the previous day, and complained only of a bandlike headache. An infectious disease consultation was obtained, and the patient was diagnosed with an allergic reaction to the iohexol. Diagnosis was based on the negative Gram stain result, negative culture result, and rapid resolution. Antibiotics were discontinued after results of CSF tests, blood tests, and urine cultures remained negative.

Adverse Reactions in Horses that Underwent General Anesthesia and Cervical Myelography

“…Seizures might be nonidiosyncratic reactions . Alternatively, seizures could be caused by changes in craniospinal volume, neurotoxicity of iohexol, or could be a sequel of aseptic or septic meningitis . Measurement of CSF opening pressure or invasive intracranial pressure monitoring would be necessary to correlate the incidence of adverse reactions with changes in craniospinal pressure.…”

“…In addition, nonspecific hyperthermia, neck pain and stiffness, and changes in mentation observed in the postmyelography period reported in our study could be signs of aseptic meningitis or meningoencephalitis. Development of aseptic meningitis or meningoencephalitis after intrathecal administration of iodinated contrast medium in humans is thought to be related to changes in intrathecal osmolarity, direct toxicity, or an immune‐mediated process, but the pathophysiology is poorly understood . Several horses with nonspecific hyperthermia in the postmyelography period were diagnosed with respiratory or gastrointestinal adverse effects, highlighting the importance of careful examination of horses postmyelography.…”

“…The most common mild adverse effects after iohexol myelography in people are headache, nausea, vomiting, and dizziness . Severe complications reported in people include seizures, aseptic or septic meningitis, meningoencephalitis, intracranial hemorrhage, spinal hematoma, encephalopathy, transient confusion, and paraplegia . Aseptic meningitis as a sequel of intrathecal injection of nonionic contrast material also has been reported in dogs…”

Pressure–volume Index‐based Volume Calculation of Contrast Medium for Atlanto‐occipital Myelography in Dogs

“…The prevalence of seizures after myelography varies between 1% and 21.4%, even when using second‐generation iodinated compounds , . The seizures are attributed to the chemical effect of the contrast medium . However, the increase in subarachnoid pressure from the injection also may contribute to adverse effects.…”

Comparison Between Magnetic Resonance Imaging Estimates of Extracranial Cerebrospinal Fluid Volume and Physical Measurements in Healthy Dogs

“…I n veterinary practice, myelography is still commonly used to examine the spinal cord and to diagnose and locate disc herniation. Postmyelography epileptic and clonic spasms are frequently recorded along with paralysis and/or lack of locomotor coordination after the patient regains consciousness . As these complications are more likely to occur in larger dogs, some authors recommend using contrast media dosages that are not proportional to the bodyweight of the patient .…”