Motor Cortex Stimulation for Intractable Pain

Richard K. Osenbach, M.D.

Disclosures

Neurosurg Focus. 2006;21(6) 

In This Article

Clinical Indications

Motor cortex stimulation was initially introduced for the treatment of central poststroke and thalamic pain[32,33] (Fig. 1), and soon thereafter for trigeminal neuropathic pain.[15] To date, the largest experience with MCS has been in these subgroups of patients. Based on the encouraging results obtained, the indications for MCS have evolved to include a variety of other pain syndromes ( Table 1 ). For some of these conditions, such as poststroke pain, true anesthesia dolorosa, and postherpetic neuralgia (particularly involving the trigeminal distribution), MCS might be viewed as a primary surgical treatment, because other surgical options are unlikely to be effective. For other conditions, such as CRPS I and brachial plexus avulsion, MCS may be considered for patients in whom other procedures have been attempted and have failed to provide adequate analgesia.

Figure 1.

Pretreatment computed tomography scan obtained in a patient with a left thalamic hemorrhage. A thalamic pain syndrome with right hemibody pain developed, and this patient was thought to be a good candidate for a trial of MCS.

A good example may be patients with CRPS I, also called reflex sympathetic dystrophy. The current surgical options for patients with medically refractory CRPS I include SCS, intrathecal infusion, and sympathectomy. Although in most patients with CRPS I the pain can be effectively managed with one or more of the aforementioned procedures, some patients, particularly those with long-standing end-stage CRPS, may fail to respond to all conventional therapy, and MCS might represent a reasonable option in some of them. A second example is deafferentation pain secondary to brachial plexus avulsion injury.[27] Brachial plexus avulsion represents the single best indication for DREZ lesioning, which is effective in more than 80% of patients with this condition. For patients who fail to receive adequate pain relief from DREZ lesioning, however, MCS may be an attractive option be cause other surgical treatments are rarely effective. In deed, given the fact that DREZ lesioning is a destructive and irreversible procedure, it might even be reasonable to consider MCS as a primary treatment for pain following plexus avulsion, notwithstanding the published accounts describing successful application of the DREZ procedure for this condition.

Although MCS has clearly been shown to be beneficial in carefully selected patients and has been used with increasing frequency, it must be noted that the US Food and Drug Administration has not approved the device(s) for this particular indication. Therefore, patients considered for MCS should be advised preoperatively that implantation of epidural electrodes for cortical stimulation currently represents an "off-label" application of this technology.

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