Intracerebroventricular pain treatment with analgesic mixtures including ziconotide for intractable pain

Abstract

Intracerebroventricular (ICV) administration of opioids for control of intractable cancer pain has been used since 1982. We present here our experience of intracerebroventricular administration of pain treatments including ziconotide associated with morphine and ropivacaine for patients resistant to a conventional approach, with nociceptive, neuropathic, or mixed pain. These clinical cases were conducted with patients suffering from refractory pain, more than 6/10 on a numerical pain rating scale (NPRS) while on high-dose medical treatment and/ or intolerance with significant side effects from oral medication. The baseline study visit included a physical examination and an assessment of pain intensity on a NPRS. Under general anesthesia, a neuronavigation device was used to place the catheter on the floor of the third ventricle, supported by an endoscope. Then, drugs were injected in the cerebroventricular system, through a pump (external or subcutaneous). The primary objective was to measure pain evaluation with ICV treatment after a complete withdrawal of other medications. Four patients were enrolled: 3 with intractable cancer pain and one with central neuropathic pain. The median NPRS at baseline was 9.5 [8.5; 19]. The mean NPRS after one month was 3.5 [3; 4.5]. Ziconotide was initiated at 0.48 µg/dy and up to a median of 1.2 µg/dy [1.0; 1.56]. The median dose of morphine and ropivacaine used initially was respectively 0.36 mg/dy [0.24; 0.66] up to 0.6 mg/dy [0.45; 4.63] and 1.2 mg/dy [0; 2.4] up to 2.23 mg/dy [1.2; 3.35]. Minor side effects were initially observed but transiently. One psychiatric agitation required discontinuation of ziconotide infusion. For intractable pain, using ziconotide by intracerebroventricular infusion seems safe and efficient, specifically for chronic neoplastic pain of cervicocephalic, thoracic, or diffuse origin and also for pain arising from a central neuropathic mechanism.