In a study of 44 patients with different types of
chronic pain, mostly associated with deafferentation, chronic percutaneous epidural spinal stimulation has proved useful treatment achieving an initial 52% incidence of
pain amelioration overall. Long-term result showed at six months in 86%, at 1 year in 90%, although technical problems, which included
electrode displacement and required minor operative readjustment, affected 48% of those permanently implanted. No other complications were seen. Success bore no relationship to quality of
pain reported by the patients or to duration of
pain. The patients with
denervation caused by nerve or root lesions responded better than those with cord lesions even though electrical
paresthesia were delivered to the area of
pain in each case. A decline in effectiveness with time was noted in small numbers of our cases despite persistence of
paresthesia in the area of
pain. It is suggested that late failure reflects plasticity of the nervous system in adapting to new inputs.
Morphine study was carried out in some of these patients.
Morphine did not help to ameliorate the
pain in many cases with
deafferentation pain. And also
Naloxone was administered during successful
pain-relieving stimulation. This did not result in recurrence of
pain. The Somato Sensory Responses were recorded in 25 patients before and during neurostimulation. When stimulation was applied the late component was suppressed in most of those who enjoyed a good result. The early component was not changed in those patients even during stimulation. These results suggest that
spinal cord stimulation would suppress the denervative
hypersensitivity of dorsal horn in the patients with
deafferentation pain.(ABSTRACT TRUNCATED AT 250 WORDS)