A 55-year-old woman with a history of postlaminectomy syndrome after a discectomy surgery performed 8 years ago.
After failure of initial therapy with oral morphine we implanted an intrathecal infusion pump Medtronic Syned® II with 40 ml reservoir and 0.14 ml catheter.
The treatment was effective for 3 years, after which the symptomatic relief was progressively lower until it was null in the last 6 months.
We performed several increases in the daily dose of morphine and the patient showed no improvement.
A radiological study was performed to confirm the diagnosis of suspected catheter migration.
Establishment of this situation
The patient was operated under local anesthesia and sedation, requiring catheter replacement and subsequent connection to the subcutaneous pump of abdominal localization.
The previous daily dose of intradural puncture for pain therapy was 4 mg/day.
The suspicion that the patient did not receive this dose for months was suspected. We restarted therapy with a bolus dose of 1.4 mg, which was administered for 2 hours, and 1 mg/day of maintenance.
Ten hours after the start of infusion, the patient begins with nausea and vomiting accompanied by vertigo.
The patient was treated with a round-setrone and a sulphide, showing improvement.
At 22 hours the patient has respiratory depression with loss of consciousness, desaturation and respiratory acidosis.
We started treatment with 0.8 mg bolus naloxone and assisted ventilation.
The patient recovers spontaneous respiration, but remains obtundated, and it was decided to transfer her to the resuscitation unit to continue treatment and monitoring.
We started treatment with corticosteroids and continuous intravenous infusion of naloxone at a dose of 2 mg/h.
Radiological examination confirms the correct position of the catheter.
The pump was fixed and morphine infusion was replaced by saline solution.
By being able to communicate with her, he refers not to hear us and the exploration showed bilateral hearing loss.
The constants are HR 85 bpm, TA 95/45 mm Hg and temperature 37oC.
There is no neurological symptoms and examination by equipment is normal.
Interconsultation with the otorhinolaryngology service was requested.
After a thorough examination, the patient was diagnosed with sensorineural hearing loss, which was not justified.
After an observation period of 1 hour with progressive increase of naloxone to doses of 6 mg/h, the patient recovers the hearing slowly.
We decided to keep the patient in the recovery unit for observation for a period of 24 hours.
We maintain the treatment described above for the risk of a new respiratory depression.
The patient was discharged without residual hearing loss and was diagnosed with hypoacusis due to morphine intoxication.
