Chronic neuropathic pain management in spinal cord injury patients. What is the efficacy of pharmacological treatments with a general mode of administration? (oral, transdermal, intravenous).

INTRODUCTION: The pharmacological treatment of patients with spinal cord injury (SCI) pain remains challenging despite new available drugs. Such treatment should always be viewed in the context of global pain management in these patients. To date few clinical trials have been specifically devoted to this topic, and the implementation of treatments is generally based on results obtained in peripheral neuropathic pain. The aim of this review is to present evidence for efficacy and tolerability of pharmacological treatments in SCI pain and propose therapeutic recommendations.

MATERIAL AND METHODS: The methodology follows the guidelines of the French Society of Physical Medicine and Rehabilitation (SOFMER). It includes a systematic review of the litterature which is performed by two independent experts. The selected studies are analysed and classified into four levels of evidence (1 to 4) and three grades of recommendations are proposed (A, B, C). The review is further validated by a reading committee.

RESULTS: The efficacy of pregabalin has been confirmed in neuropathic pain associated with SCI (grade A). Gabapentin has a lower level of evidence in SCI pain (grade B) but a grade A level of evidence for efficacy in peripheral neuropathic pain. Both drugs can be proposed as first line therapy and are safe to use. Tricyclic antidepressants (TCAs) can also be proposed first line (grade B for SCI pain associated with depression, grade A for other neuropathic pain conditions), especially in patients with comorbid depressive symptoms. Tramadol can be proposed alone or in combination with antiepileptic drugs if the pain has a predominant non-neuropathic component. If these treatments fail, strong opioids can be proposed as second/third line (grade B in SCI, grade A in other types of neuropathic pain). Lamotrigine may also be proposed at this stage, particularly in patients with incomplete SCI associated with allodynia (grade B). In refractory central pain, cannabinoids may be proposed on the basis of positive results in other central pain conditions (e.g. multiple sclerosis). Intravenous ketamine and lidocaine can only be proposed in specialized centers. Drug combinations may be envisaged in case of partial response to first or second line therapy.

CONCLUSIONS: Very few pharmacological studies have dealt specifically with neuropathic pain related to SCI. Large scale studies and trials comparing several active drugs are warranted in SCI pain.