A systematic literature review of psychological characteristics as determinants of outcome for spinal cord stimulation therapy

Abstract

Psychological factors are deemed important when considering patients for suitability for Spinal Cord Stimulation (SCS). However, there is to date no consensus on which psychological characteristics or tests to undertake. This review analyses the literature to determine findings concerning the psychological characteristics observed and their impact on SCS efficacy for chronic pain. A search in the databases Cochrane, EBSCOhost (CINAHL, MEDLINE, PsycINFO and PsycARTICLES) and a hand search of reference lists from selected articles were performed, resulting in nine relevant articles. The Minnesota Multiphasic Personality Inventory was the most commonly used tool for assessing psychological factors. Only one study used a semi-structured interview instead of questionnaires. Studies lacked long term followup. Depression was identified in six studies as a factor that reduces efficacy, also as a characteristic that can improve after successful SCS by two studies. One study did not include patients with depression, due to previous research indicating depression as a contra-indication. Hypochondriasis and hysteria had conflicting results for prediction of efficacy. Mania was predicted by only two studies as a positive indicator for success. Further long term studies of psychological factors on outcome from SCS are needed.

A six year retrospective review of occipital nerve stimulation practice - controversies and challenges of an emerging technique for treating refractory headache syndromes

“…Pain duration, psychological distress, pain catastrophising, psychiatric conditions including personality disorders, history of abuse, and significant cognitive deficits are associated with poor outcomes from pain treatments in general [32]. Depression has been identified as the single most important factor predictive of efficacious Spinal Cord Stimulation [33], and other factors including somatization, anxiety, poor coping also predict poor response [34]. Reports on ONS to date have focussed on technical details and patient outcomes have centred on pain scores as a measure of patient benefit [10] and there is an absence of literature looking at patients’ psychosocial and physical status and examining outcomes with quality of life measures.…”

Spinal cord stimulation for neuropathic pain: current perspectives

“…The extent of decrease of SCS effect over time is reported variously in the literature. Some studies state that the effect has decreased 25%–50% after 2 years,30 but others only see a slight loss of efficacy over time 31. Often technical factors such as electrode problems (dislocation, breakage) have been cited to explain the loss of efficiency.…”

“…However, it remains to be determined whether there are also psychological factors below the level of severe pathology, which can negatively influence SCS efficacy. Regarding this question, the literature remains somewhat inconclusive; regarding the long-term efficiency, there are studies that find a negative correlation between the level of depression and SCS efficacy,32,33 whereas others do not 30,33…”

Spinal Cord Stimulation for Neuropathic Pain: Current Trends and Future Applications

“…Firstly, it greatly helps in excluding patients in whom a coexistence of major psychiatric diseases such as major depression, psychosis or drug abuse may hamper their response to stimulation. It must be said, however, that whether some studies found a negative association between depression and response to SCS, others did not, the evidence in literature thus being quite discordant [30,31,32]. …”

“…On the contrary, a lead electrode can move and get dislodged with body movements. In addition, it is well known from the literature that although the lead electrode is properly positioned, there may be a slight-to-moderate loss of SCS efficacy over time (in the range of 25–50%) due to both minor dislodgements of the electrode and the formation of scar tissue all around the leads [31,32]. Under these circumstances, a paddle lead might be more useful than a percutaneous one being steadily in contact with the dural surface and with negligible tilting or dislodgement in the long term.…”