10 kHz spinal cord stimulation for the treatment of non-surgical refractory back pain: subanalysis of pooled data from two prospective studies.

Spinal cord stimulation at 10 kHz is a promising therapy for non-surgical refractory back pain; however, published data are currently limited. We present a subanalysis of prospectively collected clinical outcome data for non-surgical refractory back pain patients treated with 10 kHz spinal cord stimulation, from the independent cohorts of two previous studies (SENZA-RCT and SENZA-EU). Clinical outcomes were evaluated at pre-implantation (baseline), 3 months, 6 months and 12 months following 10 kHz spinal cord stimulator implantation. These included: pain relief; responder rate (≥ 50% pain relief from baseline); remission rate (VAS ≤ 3.0 cm); disability (Oswestry Disability Index(ODI)); and opioid use. At 3 months, average back pain decreased by 70% in the combined cohort (60% in the SENZA-RCT and 78% in the SENZA-EU cohorts). This was sustained at 12 months, with a 73% back pain responder rate and 68% remission rate in the combined cohort. Leg pain relief results were generally comparable to those for back pain relief. At 12 months, the combined cohort had an average decrease in ODI scores of 15.7% points from baseline and opioid use more than halved. In conclusion, 10 kHz spinal cord stimulation reduced pain, disability and opioid consumption in non-surgical refractory back pain subjects. Application of this therapy may improve the care of non-surgical refractory back pain patients and reduce their opioid consumption.

Phenotype of patients responsive to occipital nerve stimulation for refractory head pain.

Occipital nerve stimulation (ONS) has been employed off-label for medically refractory head pain. Identification of specific headache diagnoses responding to this modality of treatment is required. Forty-four patients with medically refractory head pain and treated with ONS were invited to participate in a retrospective study including a clinical interview and, if necessary, an indomethacin test to establish the headache phenotype according to the International Classification of Headache Disorders, 2nd edn (ICHD-II). We gathered data from questionnaires before implantation, at 1 month after implantation, and at long-term follow-up. Twenty-six patients consented and were phenotyped. At 1 month follow-up and at long-term follow-up a significant decrease in all pain parameters was noted, as well as in analgesic use. Quality of sleep and quality of life improved. Patient satisfaction was generally high as 80% of patients had ≥ 50% pain relief at long-term follow-up. The overall complication rate was low, but revisions were frequent. After phenotyping, two main groups emerged: eight patients had 'Migraine without aura' (ICHD-II 1.1) and eight patients 'Constant pain caused by compression, irritation or distortion of cranial nerves or upper cervical roots by structural lesions' (ICHD-II 13.12). Overuse of symptomatic acute headache treatments was associated with less favourable long-term outcome in migraine patients. We conclude that careful clinical phenotyping may help in defining subgroups of patients with medically refractory headache that are more likely to respond to ONS. The data suggest medication overuse should be managed appropriately when considering ONS in migraine. A controlled prospective study for ONS in ICHD-II 13.12 is warranted.

Efficacy of spinal cord stimulation: 10 years of experience in a pain centre in Belgium.

Spinal cord stimulation is a minimally invasive mode of treatment in the management of certain forms of chronic pain that do not respond to conventional pain therapy. Several authors have reported encouraging findings with this technique. Over a 10-year period in a single centre, 254 patients were subjected to a trial period of spinal cord stimulation with an externalized pulse generator. Two hundred and seventeen of the patients showed satisfactory results justifying permanent implantation of a spinal cord stimulation system. In 1998, an independent physician invited 153 patients (155 pain cases), who still had the system in place and who could be contacted, for an interview. The aim of this study was to evaluate the efficacy of an implanted spinal cord stimulation system in terms of pain relief and quality of life and to assess the accuracy of the patient selection criteria. The results of this study demonstrate a high success rate as evaluated by the patients' own assessments--68% of the patients rated the result of the treatment as excellent to good after an average follow-up of almost 4 years. The resumption of work by 31% of patients who had been working before the onset of pain supports these positive findings.

Endocrine consequences of long-term intrathecal administration of opioids.

Intrathecal administration of opioids is a very efficient tool in the long-term control of intractable nonmalignant pain. However, despite the well known role of opioids in endocrine regulation, few data are available about possible effects on hypothalamic-pituitary function during this treatment. Seventy-three patients (29 men and 44 women; mean age, 49.2 +/- 11.7 yr) receiving opioids intrathecally for nonmalignant pain were enrolled for extensive endocrine investigation. At the time of hormonal determination, the mean duration of opioid treatment was 26.6 +/- 16.3 months; the mean daily dose of morphine was 4.8 +/- 3.2 mg. The control group consisted of 20 patients (11 men and 9 women; mean age, 54.2 +/- 14.0 yr) with a comparable pain syndrome but not treated with opioids. Decreased libido or impotency was present in 23 of 24 men receiving opioids. The serum testosterone level was below 9 nmol/L in 25 of 29 men and was significantly lower than that in the control group (P < 0.001). The free androgen index was below normal in 18 of 29 men and was significantly lower than that in the control group (P < 0.001). The serum LH level was less than 2 U/L in 20 of 29 men and was significantly lower than that in the control group (P < 0.001). Serum FSH was comparable in both groups. Decreased libido was present in 22 of 32 women receiving opioids. All 21 premenopausal females developed either amenorrhea or an irregular menstrual cycle, with ovulation in only 1. Serum LH, estradiol, and progesterone levels were lower in the opioid group. In all 18 postmenopausal females significantly decreased serum LH (P < 0.001) and FSH (P = 0.012) levels were found. The 24-h urinary free cortisol excretion was below 20 microg/day in 14 of 71 opioid patients and was significantly lower than that in the control group (P = 0.003). The peak cortisol response to insulin-induced hypoglycemia was below 180 microg/L in 9 of 61 opioid patients and was significantly lower than that in the nonopioid group (P = 0.002). The insulin-like growth factor I SD score was below -2 SD in 12 of 73 opioid patients and was significantly lower than that in the control group (P = 0.002). The peak GH response to hypoglycemia was below 3 microg/L in 9 of 62 subjects and was significantly lower than that in the control group (P = 0.010). Thyroid function tests and PRL levels were considered normal. No metabolic disturbances were recorded, apart from significantly decreased high density lipoprotein cholesterol levels (P = 0.041) and elevated total/high density lipoprotein cholesterol ratio (P = 0.008) in the opioid group compared to the control group. Supplementation with gonadal steroids improved sexual function in most patients. In conclusion, of all patients receiving intrathecal opioids, the large majority of men and all women developed hypogonadotropic hypogonadism, about 15% developed central hypocorticism, and about 15% developed GH deficiency. These findings suggest that further investigations are required to determine the need for systematic endocrine work-up in these patients and the necessity for substitutive therapy.

Intrathecal opioid therapy for pain: efficacy and outcomes.

Although opioid therapy has been accepted for the treatment of patients with cancer pain, its use for nonmalignant pain is still regarded as controversial due to concerns about the development of tolerance and psychological dependence. However, recent studies indicate that there is a low incidence of addiction in patients who do not have a history of addictive disorders, and opioid use is increasing for long-term treatment in patients with nonmalignant pain. This paper reviews the results from recent studies that evaluated the efficacy of intrathecal opioid delivery using a number of outcome measures. These studies demonstrate that intrathecal opioid delivery produces short-term relief of specific symptoms and improves long-term outcomes such as patient functioning (measured by increases in activities of daily living [ADLs] and capacity to work), mood, treatment satisfaction, and quality of life, as well as decreases in oral opioid use. Furthermore, these studies showed there was no development of tolerance or addiction in patients who received long-term intrathecal opioid delivery.

Drug adverse events and system complications of intrathecal opioid delivery for pain: origins, detection, manifestations, and management.

Intrathecal drug delivery is effective for the treatment of cancer and nonmalignant pain in patients who do not respond well to oral opioids, in patients who cannot tolerate the side effects associated with opioids, or in patients who show a large, permanent increase in dosage. Although intrathecal drug delivery is associated with pharmacological side effects and complications, its benefits far outweigh its risks. There are three main categories of potential adverse events associated with intrathecal drug delivery: pharmacologic side effects, surgical complications, and device-related complications. Prevention, early recognition, and prompt management of adverse events will optimize patient outcomes. Many adverse events either resolve on their own or can be managed with dosage or device adjustment. More serious complications may require surgical intervention or discontinuation of therapy. This paper will provide an overview of adverse events and complications, their origins, detection, manifestations, and management.

Treatment of failed back surgery syndrome patients with low back and leg pain: a pilot study of a new dual lead spinal cord stimulation system.

Objective. Treatment of pain associated with failed back surgery syndrome was evaluated in a pilot clinical study of a new dual lead spinal cord stimulation (SCS) system. Methods. The following data was retrospectively sought from 20 non-randomized patients at 2 centers treated by the new SCS system, instead of an implantable drug pump: 1) prior back surgeries, 2) pain and paresthesia mapping, 3) VAS ratings, 4) medication use, 5) sleep patterns, 6) physical abilities, 7) hardware problems, and 8) willingness to repeat the procedure. Two-year follow-up was sought from all patients. Results. The new dual lead SCS system provided good low back and leg paresthesia coverage. Patients reported having less pain and using fewer analgesics and narcotics during follow-up, compared to their preimplant experience. These improvements were statistically significant. Patients also improved their sleep and physical abilities during follow-up. While external hardware problems occurred, 65% of dual lead SCS patients were willing to repeat the SCS implant procedure. Conclusions. Dual lead stimulation proved beneficial for patients with low back and leg pain associated with failed back surgery syndrome.

Accidental overdosing with intraspinal morphine caused by misprogrammation of a Synchromed pump: a report of two cases.

Spinally administered opioids must be a last step in the therapeutical arsenal of chronic benigne pain. It is an invasive technique not free from adverse effects. Two chronic pain patients received an implantable Synchromed pump for treatment with spinal opiates after a trial period of resp. 3.5 and 5.5 months. Due to a misprogrammation (both on the same day) they received very high doses of spinal opiates. This caused relatively few side effects, which did not seem to require immediate treatment. A short time development of tolerance to life threatening side-effects has been proven by this accidental administration of high-dose intraspinal opiates. It is critical that care providers are knowledgeable and well-trained about implantable infusion systems. Programmation and refills must always be performed with care.