Article

Contrast-induced encephalopathy and diagnostic modalities – Can it make a difference?

Contrast-induced encephalopathy anddiagn”>2328 Correspondence / American Journal of Emergency Medicine 36 (2018) 23072335

Contrast-induced encephalopathy and diagnostic modalities – Can it make a difference?

Dear Editor,

We read the case report by Pokersnik et al. [1] with great interest. With reference to the report, the rarity of this complication makes it a diagnostic challenge that entails the exclusion of Hemorrhagic causes. From the point of Patient safety and quality of care, we would like to underscore the utility of Hounsfield units (HU) and other reliable image modalities that can differentiate contrast in- duced encephalopathy from other mimickers based on our experi- ence [2] and the literature.

The current standard of care for such discrimination is to repeat the imaging after 24 h as the contrast staining normally washes out within 24-48 h, while hemorrhage persists for days to weeks. This traditional approach will cause unnecessary delay. This differentiation is crucial in the setting of acute stroke or trauma, when antithrombotic therapy is being considered [3].

The measurement of the density of different visible elements in the CT scan with HU can assist in differentiating blood from contrast as con- trast media present higher attenuation (100-300 HU) than blood (40 to 60 HU). Additionally, this can be done with the available CT scans with- out any extra cost and done immediately even before the patient leaves the CT suite [4].

If Dual-energy CT is available, then it should be able to differentiate contrast staining in contrast-induced neurotoxicity form hemorrhage, this discrimination is based on the differences between the photoelec- tric and Compton scattering components underlying the X-ray attenua- tion of hemorrhage and iodine. Because both phenomena are dependent on the X-ray photon energy, one can discriminate the pixel attenuation arising from these 2 effects by scanning at 2 different energy levels, such as 80 kV and 140 kV. Assuming that there can only be hem- orrhage and/or iodine (in addition to water and tissue), this information can be used to determine the amount of each material present in each voxel [5].

However, MRI is also helpful in excluding cerebral ischemia and hemorrhage with contrast extravasation as there is no change in appar- ent diffusion coefficient values [6]. The CSF examination is also useful, subarachnoid hemorrhage can be ruled out due to absence of xantochromia or red blood cells. Velden and his colleagues [7] per- formed simultaneous chemical analysis of Iomeprol concentration (io- dine contrast) in the CSF and serum. The Strong enrichment of Iomeprol in the CSF as conflicting to serum supported contrast extrava- sation rather than hemorrhage.

In view of the above, application and utilization of these technolo- gies shall be discussed while handling cases of CIE and the knowledge thus gained shall be imparted to students of health sciences and emer- gency physicians. Before making decisions or arriving diagnosis, let us always consider differential diagnosis and rule out each other using non-invasive and invasive technologies wherever feasible before arriv- ing diagnosis. This is important as many situations warrants supportive care, reassurance and masterly inactivity rather than active interven- tion, like cases of CIE.

Financial support

Nil.

Conflict of interest

Nil.

Subramanian Senthilkumaran

Department of Emergency and Critical Care, Be Well hospitals, Erode, Tamil

Nadu, India Corresponding author at: Department of Emergency & Critical Care Medicine, Bewell Hospitals, Erode, Tamil Nadu, India.

E-mail address: [email protected]

Namasivayam Balamurugan

Department of Neurosciences, SIMS Chellam Hospital, Salem, Tamil Nadu,

India

Narendra Nath Jena

Department of Emergency Medicine, Meenakshi Mission Hospital and

Research Centre, Madurai, Tamil Nadu, India

Ponniah Thirumalaikolundusubramanian Department of Internal Medicine, Chennai Medical College Hospital and Research Center, Irungalur, Trichy, Tamil Nadu, India

16 April 2018

https://doi.org/10.1016/j.ajem.2018.04.042

References

  1. Pokersnik JA, Lou L, Simon EL. Contrast-induced encephalopathy presenting as acute subarachnoid hemorrhage. Am J Emerg Med 2018 Jun;36(6):1122.e3-1122.e4.
  2. Senthilkumaran S, Karthikeyan N, Balamurugan N, Thirumalaikolundusubramanian P. Hounsfield units in pseudo subarachnoid hemorrhage: worth looking for. Clin Exp Emerg Med 2017 Sep 30;4(3):186-7.
  3. Mericle RA, Lopes DK, Fronckowiak MD, et al. A grading scale to predict outcomes after intra-arterial thrombolysis for stroke complicated by contrast extravasation. Neurosurgery 2000;46:1307-14.
  4. Senthilkumaran S, Sweni S, Balamurugan N, Jena NN, Thirumalaikolundusubramanian P.

    Hounsfield units in pseudo-subarachnoid hemorrhage-an old yet fascinating tool. Am J Emerg Med 2015;33:1095.

    Phan CM, Yoo AJ, Hirsch JA, Nogueira RG, Gupta R. Differentiation of hemorrhage from iodinated contrast in different intracranial compartments using dual-energy Head CT. AJNR Am J Neuroradiol 33 (6): 1088-94.

  5. Yu J, Dangas G. Commentary: new insights into the risk factors of contrast-induced encephalopathy. J Endovasc Ther 2011;18:545-6.
  6. Velden J, Milz P, Winkler F, Seelos K, Hamann GF. Nonionic contrast neurotoxicity after coronary angiography mimicking subarachnoid hemorrhage. Eur Neurol 2003; 49:249-51.

    Concussion awareness among children and their care givers

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