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Myelography and residual contrast in panoramic radiography: case report

Presença de contraste residual de mielografia em radiografia panorãmica: relato de caso

ABSTRACT

Myodil or pantopaque is an oil-based contrast solution often used up to 1980 for myelography, cisternography, and ventilography. Oilbased contrasts have a very slow clearance time in the cerebrospinal fluids and may encapsulate for decades and remain in the central nervous system and the interior of the spine. The knowledge of the existence of this rare condition coming from other radiographictests of the past, described in this clinical case, is essential when atypical radiographic images are found.

Indexing terms
Contrast media; Myelography; Radiography; panoramic

RESUMO

O myodil ou o Pantopaque é uma solução de contraste a base de óleo usada frequentemente até 1980 para mielografia, cisternografia e ventilografia. Os contrastes à base de óleo têm um tempo de liberação muito lento nos fluidos cefalorraquidianos e podem encapsular por décadas e permanecer no sistema nervoso central e no interior da coluna vertebral. O conhecimento da existência dessa condição rara proveniente de outros exames radiográficos do passado, descritos neste caso clínico, é essencial quando são encontradas imagens radiográficas atípicas, principalmente em radiografia panorâmicas.

Termos de indexação
Meios de contraste; Mielografia; Radiografia panorâmica

INTRODUCTION

Contrast agents are drugs commonly used in medical imaging tests, which allow a better visualization of the tissues and structures of the body, being indispensable for the diagnosis of some pathologies [11 Ertan G, Ulus S, Albayrak BS, Cila A. Revisiting a historical phenomenon: myodil droplets in the subarachnoid space. Neurol India. 2018;66:269-70. http://dx.doi.org/10.4103/0028-3886.222843
https://doi.org/10.4103/0028-3886.222843...
,22 Kanikadaley V. Residual intradural oil-based contrast agent: a case report. GMJ, ASM 2015; 4(S1):29-35. http://dx.doi.org/10.26650/eor.2018.532
https://doi.org/10.26650/eor.2018.532...
].

Pantopaque or Myodil is an oil-based radiopaque contrast agent frequently used up to the 1980’s in myelography tests, which consists of the application of the contrast substance in the spinal subarachnoid space, in order to evaluate any abnormalities inside the spine [33 Lee SK, Kim DH, Kim SH et al. Asymptomatic thoracic Pantopaque cyst mimicking an intradural extramedullary lipoma on MR images. Eur Spine J. 2013; 22(Suppl 3): 321. http://dx.doi.org/10.1007/s00586-012-2364-2
https://doi.org/10.1007/s00586-012-2364-...
].

According to Kanikadaley [11 Ertan G, Ulus S, Albayrak BS, Cila A. Revisiting a historical phenomenon: myodil droplets in the subarachnoid space. Neurol India. 2018;66:269-70. http://dx.doi.org/10.4103/0028-3886.222843
https://doi.org/10.4103/0028-3886.222843...
], oil-based contrasts are known for their low clearance rate in the cerebrospinal fluid, which can remain in the body for more than 3 decades without painful symptoms. For this reason, the contrast substances were gradually replaced with water-soluble media, which can be absorbed and excreted within a few minutes after the injection.

The present study aims to report a clinical case of radiographic findings compatible with residual contrast, in order to show that, despite the rarity, such cases can occur and the dentist must be able to differentiate it from any abnormalities.

CASE REPORT

Myelography and residual contrast

A 62-year-old male patient attended the dental clinic for prosthetic rehabilitation. The clinical examination revealed the absence of some dental elements, and other anatomical structures within normality. The anamnesis patient reported having lost these elements throughout life, due to carious lesion and / or periodontal problems. He did not report any systemic changes.

Panoramic radiographic test revealed radiopaque images circumscribed in the base region of the skull, and subarachnoid space on both sides, but more evident on the right side (figure 1).

Figure 1
Panoramic radiography - Circumscribed radiopaque images located in the subarachnoid space on both sides, compatible with residual contrast.

After being asked if he had to use a contrast solution, the patient reported that when he was 30 years old he had a lumbar disc problem caused by his practice and had a “spine radiography” done. The patient also reported that he did not judged relevant at the time to tell his dentist about the radiography and its procedures, once he thought it was not of dental interest. However, radiopaque images are shown in head and neck tests which proves the importance of detailed anamneses.

The radiopaque images found on panoramic radiography are a characteristic of the contrast substance residue and, in the clinical case, remained undetected and asymptomatic for decades.

After being presented with the intentions of the study, the patient signed a free and informed consent form.

DISCUSSION

Since it was introduced in 1919, myelography has been used universally as the test of choice to diagnose pathologies in the spinal cord. Contrast agents are used to facilitate examination analysis. As of 1922, oil-based substances were introduced, which provided an improvement in the image of the subarachnoid space [11 Ertan G, Ulus S, Albayrak BS, Cila A. Revisiting a historical phenomenon: myodil droplets in the subarachnoid space. Neurol India. 2018;66:269-70. http://dx.doi.org/10.4103/0028-3886.222843
https://doi.org/10.4103/0028-3886.222843...
,33 Lee SK, Kim DH, Kim SH et al. Asymptomatic thoracic Pantopaque cyst mimicking an intradural extramedullary lipoma on MR images. Eur Spine J. 2013; 22(Suppl 3): 321. http://dx.doi.org/10.1007/s00586-012-2364-2
https://doi.org/10.1007/s00586-012-2364-...
].

According to Ramsey et al. [22 Kanikadaley V. Residual intradural oil-based contrast agent: a case report. GMJ, ASM 2015; 4(S1):29-35. http://dx.doi.org/10.26650/eor.2018.532
https://doi.org/10.26650/eor.2018.532...
], Iofendylate, myodil or pantopaque was introduced in 1944 and since then the most widely used. Pantopaque is a mixture of chemical elements that contains associated iodide, is a yellowish, almost colorless, oily liquid that bleaches when exposed to sunlight.

Myodil may persist in the central nervous system as encapsulated drops that become calcified or as a thin film that can cause a systemic toxic reaction in the body. In the literature it is possible to find reports of the appearance of residual contrast mainly in the subarachnoid space, in the extramedullary spaces [44 Pawl R. History of myelography with pantopaque contributing to arachnoiditis. Surg Neurol Int. 2014; 5:S315-6. http://dx.doi.org/10.4103/2152-7806.139617
https://doi.org/10.4103/2152-7806.139617...

5 Ramsey GH, French JD e Strain WH. Iodinated organic compounds as contrast media in radiographic diagnosis IV: Pantopaque myelography. Radiol. 1944;43:236-240. http://dx.doi.org/10.1148/43.3.236
https://doi.org/10.1148/43.3.236...
-66 White AC. Prolonged elevation of serum protein-bound iodine following myelography with myodil. Br J Radiol. 1972;45:21-23. http://dx.doi.org/10.1259/0007-1285-45-529-21
https://doi.org/10.1259/0007-1285-45-529...
]. In our case, we observed circumscribed radiopaque images, suggestive of encapsulated droplets, which justifies asymptomatology. Some authors have reported that patients may suffer from post-myelography headaches for up to 6 months, as a consequence of the blood irritation that oil-based contrasts can cause [77 Kaugars GE, Campbell RL, Shulman J. Residual intracranial contrast agent. Oral Surg, Oral Med, Oral Pathol. 1985; 60:6:679-681. http://dx.doi.org/10.1016/0030-4220(85)90377-9
https://doi.org/10.1016/0030-4220(85)903...
,88 Oo M, Wang Z, Sakakibara T, Kasai Y. Magnetic resonance imaging findings of remnants of an intradural oil-based contrast agent: report of a case. J Spinal Cord Med. 2012; 35(3):187-190. http://dx.doi.org/10.1179/2045772312Y.0000000002
https://doi.org/10.1179/2045772312Y.0000...
].

The potential complications associated with pantopaque, with no possible prevention or any treatment modalities, led to the search for better contrast agents and the decline of the use of this substance [99 Junck L, Marshall WH. Neurotoxicity of radiocontrast agents. Ann Neurol. 1983;13:469-84. http://dx.doi.org/10.1002/ana.410130502
https://doi.org/10.1002/ana.410130502...
]. According to Navani et al. [1010 Navani A, Dominguez CL, Hald JK, Fishman SM. An injection from the past: fluoroscopic evidence of remote injections of radiopaque substances. Reg Anesth Pain Med. 2006; 31(1):82-5. http://dx.doi.org/10.1016/j.rapm.2005.07.193
https://doi.org/10.1016/j.rapm.2005.07.1...
], contrast agents should not have acute or chronic effects on the meninges, spinal cord or nerve roots, should remain sufficient for a complete radiological study, but should be completely excreted as soon as possible. Currently, Omnipaque and Iopamidol are some of the most commonly used water soluble contrasts.

Myelography and residual contrast

With the increasing use of CT scans and magnetic resonance imaging, the use of myelography decreased and, consequently, the use of iofendilate [1111 Rahimizadeh A. Imaging Features of Retained Subdural Pantopaque 28 Years after Myelography. World Spinal Column J. 2012;3(1):15-18. http://dx.doi.org/10.1590/S1808-18512013000100018
https://doi.org/10.1590/S1808-1851201300...
]. However, even though rare, myodil residues can still be visualized and can even be interpreted as diseases. When atypical radiographic findings are found, associated with a careful anamnesis, the health professional should consider the possibility of residual contrasting substances from other radiographic tests. This study reports a clinical case of radiographic findings, compatible with asymptomatic myodil residues 3 decades after its application. This emphasizes the need for awareness on these findings, which, even though rarely occurring, must be diagnosed with accuracy and expertise.

CONCLUSION

Residues of oil-based contrasts have decreased over the years. However, they are commonly seen on panoramic radiographs, especially in elderly patients, as evidenced in the clinical case. Therefore, we aim to increase awareness that this condition is latent and can be observed with certain frequency in imaging, being central for accurate diagnosis

How to cite this article

REFERENCES

  • 1
    Ertan G, Ulus S, Albayrak BS, Cila A. Revisiting a historical phenomenon: myodil droplets in the subarachnoid space. Neurol India. 2018;66:269-70. http://dx.doi.org/10.4103/0028-3886.222843
    » https://doi.org/10.4103/0028-3886.222843
  • 2
    Kanikadaley V. Residual intradural oil-based contrast agent: a case report. GMJ, ASM 2015; 4(S1):29-35. http://dx.doi.org/10.26650/eor.2018.532
    » https://doi.org/10.26650/eor.2018.532
  • 3
    Lee SK, Kim DH, Kim SH et al. Asymptomatic thoracic Pantopaque cyst mimicking an intradural extramedullary lipoma on MR images. Eur Spine J. 2013; 22(Suppl 3): 321. http://dx.doi.org/10.1007/s00586-012-2364-2
    » https://doi.org/10.1007/s00586-012-2364-2
  • 4
    Pawl R. History of myelography with pantopaque contributing to arachnoiditis. Surg Neurol Int. 2014; 5:S315-6. http://dx.doi.org/10.4103/2152-7806.139617
    » https://doi.org/10.4103/2152-7806.139617
  • 5
    Ramsey GH, French JD e Strain WH. Iodinated organic compounds as contrast media in radiographic diagnosis IV: Pantopaque myelography. Radiol. 1944;43:236-240. http://dx.doi.org/10.1148/43.3.236
    » https://doi.org/10.1148/43.3.236
  • 6
    White AC. Prolonged elevation of serum protein-bound iodine following myelography with myodil. Br J Radiol. 1972;45:21-23. http://dx.doi.org/10.1259/0007-1285-45-529-21
    » https://doi.org/10.1259/0007-1285-45-529-21
  • 7
    Kaugars GE, Campbell RL, Shulman J. Residual intracranial contrast agent. Oral Surg, Oral Med, Oral Pathol. 1985; 60:6:679-681. http://dx.doi.org/10.1016/0030-4220(85)90377-9
    » https://doi.org/10.1016/0030-4220(85)90377-9
  • 8
    Oo M, Wang Z, Sakakibara T, Kasai Y. Magnetic resonance imaging findings of remnants of an intradural oil-based contrast agent: report of a case. J Spinal Cord Med. 2012; 35(3):187-190. http://dx.doi.org/10.1179/2045772312Y.0000000002
    » https://doi.org/10.1179/2045772312Y.0000000002
  • 9
    Junck L, Marshall WH. Neurotoxicity of radiocontrast agents. Ann Neurol. 1983;13:469-84. http://dx.doi.org/10.1002/ana.410130502
    » https://doi.org/10.1002/ana.410130502
  • 10
    Navani A, Dominguez CL, Hald JK, Fishman SM. An injection from the past: fluoroscopic evidence of remote injections of radiopaque substances. Reg Anesth Pain Med. 2006; 31(1):82-5. http://dx.doi.org/10.1016/j.rapm.2005.07.193
    » https://doi.org/10.1016/j.rapm.2005.07.193
  • 11
    Rahimizadeh A. Imaging Features of Retained Subdural Pantopaque 28 Years after Myelography. World Spinal Column J. 2012;3(1):15-18. http://dx.doi.org/10.1590/S1808-18512013000100018
    » https://doi.org/10.1590/S1808-18512013000100018

Publication Dates

  • Publication in this collection
    28 Oct 2019
  • Date of issue
    2019

History

  • Received
    16 Oct 2018
  • Reviewed
    14 Dec 2018
  • Accepted
    07 Feb 2019
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