Faculty Bibliography

OBJECTIVE: The clinical entity of thoracic radiculopathy following spinal cord stimulator (SCS) placement has not been previously described. MATERIALS AND METHODS: A retrospective review of prospectively acquired data on 172 patients, having undergone thoracic SCS placement at our institution, was performed. In addition, four patients were implanted at outside institutions, and were referred for revision. We examine our early experience with placement of thoracic SCS in surgically treated patients with chronic pain and 15 associated specific postoperative radicular pain complications along respective thoracic dermatomes. We postulate that preexisting thoracic spinal pathology affords less compliance in the placement of larger paddles, and subsequent radicular pain in a band-like abdominal fashion. RESULTS: A syndrome of thoracic radiculopathy, presenting as intractable lower thoracic or abdominal wall pain occurring in the immediate postoperative period, was identified in 15 patients. These patients subsequently underwent revision surgery, with either a more extensive laminectomy to further decompress the dorsal nerve roots or lead removal, both of which resulted in near immediate relief of symptoms. CONCLUSIONS: Thoracic radiculopathy may occur following SCS paddle lead placement. This clinical syndrome is characterized by its immediate postoperative development, band-like thoracic or abdominal pain pattern, severe pain that both overwhelms the incisional pain and is refractory to medications, and absence of motor deficit. The lateral placement of paddle leads increases the risk of radicular symptoms. Preoperative thoracic spine magnetic resonance imaging may be helpful in identifying patients who may be susceptible to this syndrome.

An 84-year-old man underwent deep brain stimulation (DBS) for mixed rest-action tremors. One year later, he developed a keratoma where the DBS wire emerged from the insertion cap. It was suspected to be a foreign body reaction and removed by a dermatologist but returned and grew conically over the next 4 years, reaching a height of 4 cm (figure). The surrounding skin began to break down with protrusion of the adjacent extension wire. We recommended removal of the lead but due to continued efficacy and advanced age, he decided to continue with the stimulator in place under observation.

BACKGROUND: Deep brain stimulation (DBS) remains an experimental but promising treatment for patients with severe refractory Gilles de la Tourette syndrome (TS). Controversial issues include the selection of patients (age and clinical presentation), the choice of brain targets to obtain optimal patient-specific outcomes, and the risk of surgery- and stimulation-related serious adverse events. METHODS: This report describes our open-label experience with eight patients with severe refractory malignant TS treated with DBS. The electrodes were placed in the midline thalamic nuclei or globus pallidus, pars internus, or both. Tics were clinically assessed in all patients pre- and postoperatively using the Modified Rush Video Protocol and the Yale Global Tic Severity Scale (YGTSS). RESULTS: Although three patients had marked postoperative improvement in their tics (>50% improvement on the YGTSS), the majority did not reach this level of clinical improvement. Two patients had to have their DBS leads removed (one because of postoperative infection and another because of lack of benefit). DISCUSSION: Our clinical experience supports the urgent need for more data and refinements in interventions and outcome measurements for severe, malignant, and medication-refractory TS. Because TS is not an etiologically homogenous clinical entity, the inclusion criteria for DBS patients and the choice of brain targets will require more refinement.

Background: Chronic migraine (CM) is a debilitating neurological disorder with few treatment options. Peripheral nerve stimulation (PNS) of the occipital nerves is a potentially promising therapy for CM patients. Methods: In this randomized, controlled multicenter study, patients diagnosed with CM were implanted with a neurostimulation device near the occipital nerves and randomized 2:1 to active (n = 105) or sham (n = 52) stimulation. The primary endpoint was a difference in the percentage of responders (defined as patients that achieved a >/=50% reduction in mean daily visual analog scale scores) in each group at 12 weeks. Results: There was not a significant difference in the percentage of responders in the Active compared with the Control group (95% lower confidence bound (LCB) of -0.06; p = 0.55). However, there was a significant difference in the percentage of patients that achieved a 30% reduction (p = 0.01). Importantly, compared with sham-treated patients, there were also significant differences in reduction of number of headache days (Active Group = 6.1, baseline = 22.4; Control Group = 3.0, baseline = 20.1; p = 0.008), migraine-related disability (p = 0.001) and direct reports of pain relief (p = 0.001). The most common adverse event was persistent implant site pain. Conclusion: Although this study failed to meet its primary endpoint, this is the first large-scale study of PNS of the occipital nerves in CM patients that showed significant reductions in pain, headache days, and migraine-related disability. Additional controlled studies using endpoints that have recently been identified and accepted as clinically meaningful are warranted in this highly disabled patient population with a large unmet medical need. Trial registration: Clinical trials.gov (NCT00615342).

BACKGROUND: Chronic occipital and suboccipital headache is a common symptom in patients with Chiari I malformation (CMI). These headaches may persist despite appropriate surgical treatment of the underlying pathology via suboccipital decompression, duraplasty and cerebrospinal fluid diversion. Occipital nerve stimulation (ONS) has been shown to be effective in the treatment of a variety of occipital headache/pain syndromes. OBJECTIVE: We retrospectively reviewed our experience with ONS in patients with a primary diagnosis of Chiari malformation (CM) and a history of chronic occipital pain intractable to medical and surgical therapies. METHODS: We present a retrospective analysis of our series of 22 patients with CM and persistent occipital headaches who underwent occipital neurostimulator trials and, following successful trials, permanent stimulator placement. A trial was considered successful with greater than 50% pain relief using a standard visual analog score (VAS). Patients with a successful trial underwent permanent placement approximately one to two weeks later. Patients were assessed postoperatively for pain relief via VAS. RESULTS: Sixty-eight percent (15/22) of patients had a successful stimulator trial and proceeded to permanent implant. Of those implanted, 13/15 (87%) reported continued pain relief at a mean follow-up of 18.9 months (6 - 51 months). Device-related complications requiring additional surgeries occurred in 40% of patients. CONCLUSION: Occipital stimulation may provide significant long-term pain relief in selected CMI patients with persistent occipital pain. Larger and longer-term studies are needed to further define appropriate patient selection criteria as well as to refine the surgical technique to minimize device-related complications.

BACKGROUND:: Placement of spinal cord stimulating paddle leads has traditionally been performed using local anesthesia with intravenous sedation to allow for intraoperative confirmation of appropriate placement. It may be difficult to maintain appropriate sedation in certain patients due to medical comorbidities. Furthermore, patients undergoing lead revision frequently have extensive epidural scarring, requiring multi-level laminectomies to place the electrode appropriately. OBJECTIVE:: We report our technique of neurophysiologic monitoring which allows these procedures to be performed under general anesthesia. METHODS:: Data from 78 patients who underwent electromyography (EMG) during laminectomy for paddle lead placement were retrospectively reviewed. 70 patients presented for first-time permanent system placement following a successful trial, and 8 were referred for revision or replacement of previously functioning systems. Surgeries were performed under general anesthesia, with fluoroscopic guidance. EMG was used to help define the physiologic midline of the spinal cord and guide appropriate lead placement. Somatosensory evoked potentials (SSEP) were used as an adjunct to minimize the possibility of neural injury. RESULTS:: Immediately postoperatively, 75 of 78 patients reported that the paresthesia coverage was as good (or better) as that of the SCS trial. At long-term follow-up, 1 system was removed for infection, and 6 systems were explanted for lack of efficacy. A total of 64 of the 78 implanted patients reported continued pain relief with stimulator use. Revision surgery was performed in 9 patients. CONCLUSION:: The use of intraoperative electrophysiology for the placement of SCS paddle leads under general anesthesia is a safe and efficacious alternative to awake surgery.

The frequency with which patients with atypical parkinsonism and advanced motor symptoms undergo deep brain stimulation (DBS) procedures is unknown. However, the potential exposure of these patients to unnecessary surgical risks makes their identification critical. As many as 15% of patients enrolled in recent early Parkinson disease (PD) trials have been found to lack evidence of a dopaminergic deficit following PET or SPECT imaging. This suggests that a number of patients with parkinsonism who are referred for DBS may not have idiopathic PD. The authors report on 2 patients with probable psychogenic parkinsonism who presented for DBS surgery. They found that both patients had normal caudate and putamen [(18)F]-fluorodopa uptake on PET imaging, along with normal expression of specific disease-related metabolic networks for PD and multiple system atrophy, a common form of atypical neurodegenerative parkinsonism. The clinical and PET findings in these patients highlight the role of functional imaging in assisting clinical decision making when the diagnosis is uncertain.