Progress in neurological surgery
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Dorsal root ganglion (DRG) stimulation has recently emerged as a new neuromodulation modality that stays on the intersection of the peripheral and central nervous system. With DRG location within the spinal column and with electrodes for DRG stimulation placed through the intraspinal epidural space, it may make more sense to group DRG stimulation together with more commonly used spinal cord stimulation (SCS) rather than peripheral nerve stimulation (PNS), particularly if one agrees that the stimulation delivered to DRG partly works downstream at the spinal cord level. ⋯ In addition to its efficacy, DRG stimulation of the spinal cord is associated with a lower rate of migrations and lack of positional side effects that may be seen with SCS and PNS. Here we summarize the knowledge base and clinical evidence for DRG stimulation of the spinal cord, and present hypotheses of its mechanism of action.
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Occipital nerve stimulation (ONS) continues to be investigated for the treatment of refractory chronic migraine. Results from case series and from prospective, sham-controlled clinical trials remain inconclusive regarding the efficacy of ONS for migraine treatment. Safety and implantation techniques require improvements since rates of lead migration, infection, and persistent stimulator-related pain continue to be high. Existing data justify further ONS trials with carefully chosen primary outcome(s), adequate statistical power, and improved surgical techniques.
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Sacral neuromodulation (SNM) is a minimally invasive therapeutic option for many voiding dysfunction conditions. It is approved by the US FDA for refractory overactive bladder with and without incontinence and nonobstructive retention. Since SNM has shown a favorable response for these approved indications, other therapeutic applications have been proposed for various conditions such as painful bladder syndrome, chronic pelvic pain and neurological voiding dysfunction in both adult and pediatric age groups. ⋯ The electrode is then connected to a battery-operated pulse generator. All patients need to have a test trial period before definitive device insertion. Here we discuss SNM therapy in functional urinary disorders and the technique of device insertion with the potential pitfalls.
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Phrenic nerve stimulation is a technique used to reanimate the diaphragm of patients with central nervous system etiologies of respiratory insufficiency. Current clinical indications include congenital central hypoventilation syndrome, spinal cord injury above C4, brain stem injury, and idiopathic severe sleep apnea. Presurgical evaluation ensures proper patient selection by validating the intact circuit from the phrenic nerve through alveolar oxygenation. ⋯ After implantation, each patient progresses through a conditioning phase that strengthens the diaphragm and progressively provides independence from the mechanical ventilator. Studies indicate that patients and families experience an improved quality of life and are satisfied with the results. Phrenic nerve stimulation provides a safe and effective means for reanimating the diaphragm for certain patients with respiratory insufficiency, providing independence from mechanical ventilation.
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The interest for the sphenopalatine ganglion (SPG) in neurovascular headaches dates back to 1908 when Sluder presented his work on the role of the SPG in 'nasal headaches', which are now part of the trigeminal autonomic cephalalgias and cluster headache (ICHD-III-beta). Since then various interventions with blocking or lesional properties have targeted the SPG (transnasal injection of lidocaine and other agents, alcohol or steroid injections, radiofrequency lesions, or even ganglionectomy); success rates vary, but benefit is usually transient. ⋯ Moreover, in some patients SPG stimulation has been associated with a significant and clinically meaningful reduction in cluster headache attack frequency; this preventive effect of SPG stimulation warrants further investigation. For migraine attacks, the outcome of a proof-of-concept study using a temporary electrode implanted in the pterygopalatine fossa was less encouraging; however, an ongoing multicenter trial is evaluating the efficacy of long-term SPG stimulation against sham stimulation for acute and preventive treatment in patients with frequent migraine.