Spinal cord stimulation and pain relief in painful diabetic peripheral neuropathy

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SCIENCE
Spinal cord stimulation and pain relief in painful diabetic peripheral neuropathy
Key Take-Away: 

Spinal Cord Stimulation (SCS) treatment over a 6-month period showed clinical success rate of 59% in patients with PDPN, although this treatment is not without risks.

Painful diabetic peripheral neuropathy (PDPN) is a common complication of diabetes mellitus (DM), and prevalence of PDPN ranges from 10 to 26%. In many patients, the pain intensity causes major impact on health-related quality of life (HRQoL) and functional ability, including interference with general activity, mood, mobility, work, social relations, sleep, and enjoyment of life. The limited effectiveness of pharmacological treatment, alternative treatment strategies have been sought to alleviate pain, including spinal cord stimulation (SCS).

ABSTRACT: 
Background: 

Painful diabetic peripheral neuropathy (PDPN) is a common complication of diabetes mellitus (DM), and prevalence of PDPN ranges from 10 to 26%. In many patients, the pain intensity causes major impact on health-related quality of life (HRQoL) and functional ability, including interference with general activity, mood, mobility, work, social relations, sleep, and enjoyment of life.

The limited effectiveness of pharmacological treatment, alternative treatment strategies have been sought to alleviate pain, including spinal cord stimulation (SCS). Several observational studies suggested that SCS may have a positive effect on pain in PDPN patients, with 23 out of 31 patients (74%) reporting a pain relieving effect of ≥50% after 1 year of treatment. Therefore, we performed a multicenter randomized controlled trials (RCT) to determine whether SCS treatment in combination with best medical treatment (BMT) (SCS group) is more successful compared with BMT only (BMT group). Treatment success was defined as a ≥50% pain relief in pain intensity during daytime or nighttime, or an improvement for pain and sleep of ≥6 in the score of the patient global impression of change (PGIC) scale.

Rationale behind research

  • Pharmacological treatment is often partially effective or accompanied by unacceptable side effects, and new treatments are urgently needed
  • Limited effectiveness of pharmacological treatment, alternative treatment strategies have been sought to alleviate pain, including spinal cord stimulation (SCS)

Objective: To evaluate the effectiveness of SCS in combination with BMT (SCS group) compared with BMT only (BMT group) in patients with PDPN in the lower limbs on pain, HRQoL, and functional ability.

Methods: 

Study outcomes

  • Treatment success was predefined as ≥ 50% relief of pain intensity on during daytime or nighttime or a score of ≥6 on a 7- point Likert scale (1 = very much worse and 7 = very much improved) of the patient global impression of change (PGIC) scale for pain and sleep
  • In addition, we also measured pain severity, pain interference with daily life, pain characteristics, HRQoL, pain interference with sleep, sleep quality and quantity,​ mood, and registered medication use at all time points
  • Time-points
  • Efficacy: Baseline and at 3 and 6 months

Note: SCS patients received an extra assessment to evaluate the trial stimulation at 2 weeks

Results: 

  • Baseline: Two treatment groups were well balanced with no statistically significant difference
  • Outcomes
  • Trial stimulation was successful in 77% of the SCS patients. Treatment success was observed in 59% of the SCS and in 7% of the BMT patients (P < 0.01). Pain relief during daytime and during nighttime was reported by 41 and 36% in the SCS group and 0 and 7% in the BMT group, respectively (P < 0.05). Pain and sleep were “(very) much improved” in 55 and 36% in the SCS group, whereas no changes were seen in the BMT group, respectively (P < 0.001 and P < 0.05). One SCS patient died because of a subdural hematoma
  • Mean pain score on NRS during daytime in SCS group was reduced by 3.1 points at 6 months than with no change in pain score in the BMT group (P <0.001)
  • No significant differences between SCS and BMT groups were seen on the visual analog scale (VAS) of the EuroQol five dimensions (EQ-5D) and the mental component score (MCS) and physical component score (PCS) of the MOS SF-36
  • Sleep quantity, optimal sleep, and sleep quality were of relative poor quality in both groups, but no significant effect of SCS was observed
Conclusion: 

Treatment success was shown in 59% of patients with PDPN who were treated with SCS over a 6-month period, although this treatment is not without risks.Several anatomical or pathophysiological changes, including both peripheral and central mechanisms, have been implicated in the development of pain in diabetic peripheral neuropathy.

A possible explanation for the substantial number of negative trial stimulations might be the presence of permanent central changes in the spinal cord. Three observational studies reported a smaller mean spinal cord area index at the cervical and thoracic level in patients with diabetic peripheral neuropathy as compared with control patients without DM. However, no differences in muscle strength, reflexes (knee and achilles tendon reflex), vibration sense, and joint position in the lower extremities were found. Although SCS is effective in most patients, the treatment is not without risks. The various review studies reported that SCS to be a safe intervention in neuropathic pain patients. Our findings show that in PDPN patients, SCS in combination with BMT results in clinically relevant pain relief over a 6-month period.

Diabetes Care. 2014 Nov ; Vol 37
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