Elsevier

Brachytherapy

Volume 10, Issue 4, July–August 2011, Pages 295-298
Brachytherapy

Case Report
An unusual case of radioactive seed migration to the vertebral venous plexus and renal artery with nerve root compromise

https://doi.org/10.1016/j.brachy.2010.08.006Get rights and content

Abstract

Purpose

We report a case of prostate brachytherapy seed migration to the vertebral venous plexus and subsequently to the renal artery with corresponding dosimetry analysis describing nerve doses.

Methods and Materials

A 52-year-old male with low-risk prostate carcinoma (clinical stage T1c; Gleason score = 6; prostate-specific antigen level of 5.5) underwent transperineal permanent prostate seed implant. Postimplantation routine imaging had failed to locate the missing seed, but he subsequently presented with back pain and parathesia with radiation down the leg.

Results

CT with bony windows and MRI had located the seed in the left L5 vertebral venous plexus. Neurosurgical intervention failed to locate and remove the migrated seed. Postsurgery, the left lower limb parathesia persisted but had normal nerve conduction studies. Dose to the spinal nerve roots and nearby structures were estimated using a GEANT4 Monte Carlo simulation. Serial X-ray imaging and CT had found that the seed had further migrated to left renal hilum.

Conclusions

Seed migration to vertebral venous plexus is uncommon and to our knowledge this is the third reported case. Its subsequent migration to the renal hilum is most unusual. CT with bony windows or MRI are required if this is suspected. There is risk of spinal or nerve root damage and dose to these structures has to be estimated using GEANT4, although the tissue tolerance in the setting of low-dose rates are unknown and long-term followup of this patient is required.

Introduction

Radioactive seed brachytherapy implantation is commonly used in the treatment of localized prostate cancer. Seed migration is a well-documented complication and has been reported most commonly to the lungs [1], [2] with rates ranging from 0.7% to 55% [3], [4]. Embolization to uncommon sites, such as the right coronary artery resulting in myocardial infarction has also been reported (5). Migration to the vertebral plexus is very uncommon and to our knowledge only two cases have previously been reported (6). Here, we report an additional case resulting in nerve root compromise and subsequent migration to the renal hilum.

Section snippets

Case study

A 52-year-old male with low-risk adenocarcinoma of prostate with prostate-specific antigen level of 5.5, clinical stage T1c, Gleason score 3 + 3 = 6 was treated with low–dose rate brachytherapy. The preimplant ultrasound volume study of the prostate was measured at 42 cc. Subsequent planning was performed and 145.0 Gy was prescribed to the 100% isodose.

A total of 100 I-125 seeds with source activity of 0.368 mCi were peripherally loaded and were deployed with image intensifier and ultrasound guidance

Dosimetry study

A GEANT4 (7) Monte Carlo simulation of the single seed (Oncura 6711) (8) was performed. In this Monte Carlo study, the seed was given rotations in all three directions to match the CT data set and radiographic images. Two simulations were performed; one in a phantom with water only, and one in a voxelized phantom, including the bone material. The duration of exposure was a worst-case scenario of 60 days (i.e., from implant date to surgery date). The critical and nearby structures were contoured

Discussion

The vertebral venous plexus is a series of valveless epidural sinuses that extend from the coccyx to foramen magnum. Batson hypothesized that there is interconnectivity of this venous plexus from the pelvis to the cranium and that this system can provide a direct vascular route for spread of tumor cells, emboli, or infection [9], [10], [11], [12], [13], [14]. This theory of retrograde seeding may in part explain the predication of prostate cancer to the spine (15). Tumor cells may also

Conclusions

Seed migration to the vertebral venous plexus is uncommon and to our knowledge this is the third reported case. Its subsequent migration to the renal hilum is most unusual. CT with bony windows or MRI are required if this is suspected.

Although the dose to the nerve roots were estimated using the GEANT4 Monte Carlo simulation toolkit, it is unknown what the normal tissue tolerance is from low-dose rates.

Long-term followup is essential to monitor the patient for progression of radiation-induced

References (24)

Cited by (9)

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    Seeding of metastases to the VVP has been fairly well established in the literature, but 1 rare complication of prostate brachytherapy that has been reported is seed migration to the VVP using the pelvic venous pathway. There have been at least 4 reported cases in the literature of this finding, as reported by Nakano et al. in 2006,52 Wagner et al. in 2010,53 and Hau et al. in 2011.54 Similar to seed migration in brachytherapy for prostate cancer, there has been a report of pacemaker lead migration through the VVP into the spinal canal.55

  • Incidence and prediction of seed migration to the chest after iodine-125 brachytherapy for hepatocellular carcinoma

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    The incidence of seed migration is reported to be between 1.7% and 69.4% (14). Various locations as sites of seed movement have been documented, including the lungs (14, 18), heart (19, 20), urine (20, 21), abdomen (20–22), pelvis (20, 22), vertebral venous plexus (23, 24), sacrum (20), seminal vesicles (22), and testicular veins (25). However, the most frequent site is the chest.

  • Seed migration in prostate brachytherapy depends on experience and technique

    2012, Brachytherapy
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    Seed migration and seed loss in permanent seed prostate brachytherapy rarely influences cancer outcome and, only rarely, have clinical consequences. Rare locations of seed embolism are the vertebral venous plexus (1), the coronary artery (2), or the renal artery (1, 3). Nevertheless, the responsible physician tries to avoid it as much as possible.

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    It is well known that the most frequent site of seed migration is the lungs. Rare cases of seed migration to a coronary artery, the right ventricle, the liver, the kidneys, Batson's vertebral venous plexus, and the left testicular vein have been reported (6–14). However, to date, no cases of seed migration to a varicocele have been reported.

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Financial disclosure/Conflicts of interest: There are no financial disclosures or any conflicts of interest for either the first author or any of the coauthors.

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