Technetium-99m diethylene triamine pentaacetic acid for intrathecal administration: Are we playing with fire?

Abstract

In a letter to the editor [1] Hesslewood recently drew attention to the fact that a patient suffered serious neurological complications following the intrathecal administration of technetium-99m diethylene triamine pentaacetic acid (99mTc-DTPA). No information on the patient, type of DTPA kit or the preparation used was given. This report, however, raises the question of whether the continued use of 99mTc-DTPA for cisternography can be supported.In our previous report referenced in the letter, two of the first 15 patients we studied developed adverse reac-tions [2]. Since this publication is not readily available, a short summary of this study and of our subsequent experience using 99mTc-DTPA for intrathecal use seems to be appropriate.The adverse reactions we reported were apparently provoked by the sequestration of calcium and magnesium ions in the cerebrospinal fluid at the site of the injection. This problem was traced to the DTPA kits of a manufacturer which contained DTPA as the sodium salt and not CaNa3DTPA. Trisodium DTPA is able to strongly complex many kinds of metallic ions such as Ca, Mg and Tc, whereas calcium trisodium DTPA can bind Tc but not Ca or Mg.In isolated ischiatic nerves of rats, nerve conduction could be irreversibly blocked using HzNa3DTPA solutions, even at relatively low concentrations (5 mEq/1), while CaNa3DTPA caused no effect, even at much higher concentrations (20 mEq/1). We also found that stan- Table 1. DTPA kits containing free acid or sodium DTPAnot suitable for intrathecal use

Conus Medullaris Syndrome as a Complication of Radioisotope Cisternography

“…19 A number of serious neurological adverse reactions, presumably related to sequestration of ions in the CSF, have been reported after intrathecal injection of 99m Tc-DTPA products. 20,21 Calciumcontaining DTPA is known to be safer than the free acid or sodium DTPA, and the recommended dose of injected RI is no more than 1 mg. 20 We note that early MRI evaluation is helpful in detecting conus medullaris lesions if CMS is suspected after RI cisternography. Only two patients who received MRI within two days showed abnormal MRI findings, in contrast to other patients who received MRI after three days.…”

A low-dose radioisotope procedure for assessment of subcutaneous drug delivery systems used for slow intrathecal infusion of antispasmodic agents

“…7,8 Similarly, it was important to safeguard against possible overdose arising from rapid delivery of the antispasmodic agent during the test. Although the drug could be removed from the pump reservoir, it was not possible to empty the catheter, as the pumps implanted at our centre do not have an access port.…”

Indications for Adult and Pediatric Magnetic Resonance Imaging Gadolinium-Enhanced Cisternography and Myelography: Experience and Review of the Literature

“…RC also involves a lumbar puncture and radiation exposure. 99mTc-DTPA or 111-Indium used for radionuclide cisternography are not recognized worldwide by health authorities for intrathecal application [39].…”