Can Central Sensitization After Injury Persist as an Autonomous Pain Generator? A Comprehensive Search for Evidence.

OBJECTIVE: To conduct a comprehensive search for evidence with regard to whether central sensitization after an injury can act as a persistent autonomous pain generator after the inducing injury has healed. METHODS: We searched Medline on PubMed and the Cochrane Library, screening 3,572 abstracts, from which 937 full-text articles were obtained, with 186 of these discarded as irrelevant to the question being posed. The remaining 751 articles were studied for evidence. RESULTS: Fourteen publications were judged to provide weak evidence for the hypothesis of central sensitization as a persisting autonomous pain generator, but none addressed the question directly. No strong evidence for the affirmative answer was found. Sixty-one publications were judged to provide weak evidence for a negative answer, and ten were judged to provide strong evidence. Unexpectedly, serious weaknesses were discovered in the literature underpinning the validity of the clinical diagnosis of central sensitization in humans: 1) inappropriate extrapolation, in many publications, of laboratory animal data to humans; 2) failure to demonstrate the absence of peripheral pain generators that might be perpetuating central sensitization; and 3) many factors now shown to confound what is being measured by quantitative sensory testing, conditioned pain modulation, and the Central Sensitization Inventory. CONCLUSIONS: We found no evidence proving that central sensitization can persist as an autonomous pain generator after the initiating injury has healed. Our review has also shown that the evidential basis for the diagnosis of central sensitization in individual patients is seriously in question.

The Neurostimulation Appropriateness Consensus Committee (NACC): Recommendations on Best Practices for Cervical Neurostimulation.

INTRODUCTION: The International Neuromodulation Society convened a multispecialty group of physicians based on expertise with international representation to establish evidence-based guidance on the use of neurostimulation in the cervical region to improve outcomes. This Neurostimulation Appropriateness Consensus Committee (NACC) project intends to provide evidence-based guidance for an often-overlooked area of neurostimulation practice. MATERIALS AND METHODS: Authors were chosen based upon their clinical expertise, familiarity with the peer-reviewed literature, research productivity, and contributions to the neuromodulation literature. Section leaders supervised literature searches of MEDLINE, BioMed Central, Current Contents Connect, Embase, International Pharmaceutical Abstracts, Web of Science, Google Scholar, and PubMed from 2017 (when NACC last published guidelines) to the present. Identified studies were graded using the US Preventive Services Task Force criteria for evidence and certainty of net benefit. Recommendations are based on the strength of evidence or consensus when evidence was scant. RESULTS: The NACC examined the published literature and established evidence- and consensus-based recommendations to guide best practices. Additional guidance will occur as new evidence is developed in future iterations of this process. CONCLUSIONS: The NACC recommends best practices regarding the use of cervical neuromodulation to improve safety and efficacy. The evidence- and consensus-based recommendations should be utilized as a guide to assist decision making when clinically appropriate.

Lead Migration in Neuromodulation.

We describe a simple technique of securing surgically implanted leads for spinal cord (SCS), dorsal root ganglion (DRG) and occipital nerve stimulation (ONS), for both primary surgical implantation and correcting lead migration. This technique could also be adapted for securing percutaneously implanted leads. Thirty-nine patients underwent neurosurgical implantation of SCS, DRG, and ONS devices utilizing titanium mini-plates to obtain secure anchorage of leads to adjacent laminae close to their exit point from the epidural space, thereby minimizing the risk of further lead migration or electrode displacement. There were no cases of primary or recurrent lead migration in any patient undergoing lead placement using mini-plate anchorage. The technique appears to offer a reliable means of preventing post-operative lead migration in a variety of spinal and extra-cranial neuromodulation implants.

Peripheral neuromodulation for pain.

The past decade (1999-2009) has witnessed a dramatic increase in the use of electrical stimulation to treat chronic, intractable pain. The implantation of electrodes in close proximity to peripheral nerves, known as peripheral nerve stimulation, has been enthusiastically adopted by neurosurgeons and interventional pain specialists. The most common conditions treated with this technique are headache and complex regional pain syndromes. The potential application of peripheral neuromodulation to relatively common and frequently disabling conditions such as migraine and lower back pain represents an exciting phase in the evolution of contemporary pain surgery. We review the available evidence relating to the use of peripheral nerve stimulation for the treatment of medically refractory, chronic non-cancer pain in a variety of clinical situations, highlight the absence of randomised controlled studies, and emphasise the need for scientifically sound research in this field.

Low back pain in neurosurgical outpatients: an audit.

Low back pain is a common condition. This is a retrospective study of new referrals to neurosurgical outpatients at the Western Hospital, Victoria, Australia. Two hundred and fifteen histories were systematically reviewed. Statistical analysis was performed using univariate and multivariate analyses. Patients who had tried physiotherapy, epidural injection or had no pre-outpatient imaging were more likely to get MRI (p<0.02). Patients with clinical features of neurogenic claudication (p<0.01) or with neurological signs (p=0.02) were more likely to proceed to surgery. CT scan demonstrated significant correlation to MRI for lumbar canal stenosis, disc disease or the absence of disease (p<0.01). Referral guidelines for general practitioners regarding back pain are proposed. Recommendations are also made to facilitate the selected use of CT scan and MRI.

Cord compression secondary to intradural ossification.

The authors describe two patients presenting with a previous history of spinal trauma and a several-year history of sensory changes secondary to spinal cord compression. Both patients underwent laminectomy and spinal decompression operations. In both cases intradural bone causing neural compression was removed at operation. Potential mechanisms to explain intradural ossification and the relevant literature are reviewed.

Use of the Solis cage and local autologous bone graft for anterior cervical discectomy and fusion: early technical experience.

OBJECT: The authors prospectively evaluated the clinical and radiological outcomes after anterior cervical discectomy and fusion (ACDF) involving placement of a Solis cage and local autograft in patients who presented with symptomatic cervical spondylosis. METHODS: Twenty-two consecutive patients underwent ACDF for radiculopathy (13 cases), myeloradiculopathy (eight cases), or myelopathy alone (one case) and were assessed at 3, 6, and 12 months. Plain cervical spine radiography demonstrated a significant change in both local (p < 0.05) and regional (p < 0.05) kyphotic angles as well as an increase in segmental height (p < 0.05). At 12 months, plain radiography demonstrated Grades I, II, and III new bone formation in two, three, and 17 patients, respectively. Clinical outcomes were assessed using a visual analog scale for both neck and arm pain and a modified Japanese Orthopaedic Association (JOA) scale for myelopathy. There was a significant improvement in both arm (p < 0.05) and neck pain (p < 0.05). At 12 months, 16 (84%) of 19 and 19 (86%) of 22 patients reported complete resolution of arm pain and neck pain, respectively. There was a significant improvement in JOA scores following surgery (p < 0.05). There were two complications in the series: one case of deep venous thrombosis and one case of postoperative arm pain that resolved after conservative treatment. There were no technical complications. CONCLUSIONS: Early experience with Solis cage-augmented ACDF indicates good clinical and radiological outcomes; additionally, there are the advantages of absent donor site morbidity and anterior plate system-related morbidity.

The application of implant technology for cybernetic systems.

OBJECTIVE: To assess the usefulness, compatibility, and long-term operability of a microelectrode array into the median nerve of the left arm of a healthy volunteer, including perception of feedback stimulation and operation of an instrumented prosthetic hand. SETTING: The study was carried out from March 14 through June 18, 2002, in England and the United States. RESULTS: The blindfolded subject received feedback information, obtained from force and slip sensors on the prosthetic hand, and subsequently used the implanted device to control the hand by applying an appropriate force to grip an unseen object. Operability was also demonstrated remotely via the Internet, with the subject in New York, NY, and the prosthetic hand in Reading, England. Finally, the subject was able to control an electric wheelchair, via decoded signals from the implant device, to select the direction of travel by opening and closing his hand. The implantation did not result in infection or any perceivable loss of hand sensation or motion control. The implant was finally extracted because of mechanical fatigue of the percutaneous connection. Further testing after extraction has not indicated any measurable long-term defects in the subject. CONCLUSIONS: This implant may allow recipients to have abilities they would otherwise not possess. The response to stimulation improved considerably during the trial, suggesting that the subject learned to process the incoming information more effectively.

Cervical dural arteriovenous fistulae manifesting as subarachnoid hemorrhage: report of two cases and literature review.

Dural arteriovenous fistulas (DAVFs) in the craniocervical junction are rare but clinically important. DAVFs can be associated with subarachnoid hemorrhage (SAH), a feature distinguishing them from DAVFs in the thoracolumbar region. These lesions are often overlooked at cerebral angiography performed to assess SAH and account for a small proportion of angiographically negative SAHs. After managing two cases of cervical spinal DAVF manifesting as SAH, we analyzed all cases in the literature to identify features associated with bleeding at presentation.

Spontaneous intracranial hypotension due to thoracic disc herniation. Case report.

Spontaneous intracranial hypotension is frequently idiopathic. The authors report on a patient presenting with symptomatic intracranial hypotension caused by a transdural calcified thoracic disc herniation. Cranial magnetic resonance (MR) imaging revealed classic signs of intracranial hypotension, and a combination of spinal MR and computerized tomography myelography confirmed a mid-thoracic transdural calcified herniated disc as the cause. The patient was treated with an epidural blood patch and burr hole drainage of the subdural effusion on two occasions. Postoperatively the headache resolved and there was no neurological deficit. Thoracic disc herniation may be a cause of spontaneous intracranial hypotension.

Anterior correction of cervical kyphotic deformity: effects on myelopathy, neck pain, and sagittal alignment.

OBJECT: Cervical myelopathy may develop as a result of spinal cord compression with or without deformity. The effect of persistent kyphotic deformity on the ability of the cervical cord to recover following decompressive surgery is not known. METHODS: Between 1997 and 2000, a total of 28 patients with progressive myelopathy and kyphotic deformity underwent anterior decompression, deformity correction (0-4 degrees of lordosis), and fusion with anterior plating. Patients received clinical and radiological follow-up care, with independent analysis. Variables assessed included patient characteristics, severity of preoperative myelopathy, neck pain, and cervical sagittal alignment. Twenty-six patients (93%) underwent follow-up review for a minimum of 18 months. Two patients died: one died in the perioperative period and was excluded from further analysis, and in the other only 3 months of follow-up data could be obtained. Local deformity was corrected to neutral or lordosis in 24 cases (89%), and the overall cervical curve was corrected to neutral or lordosis in 20 cases (74%). There was a significant improvement in myelopathy scores in those patients in whom the target (0 to 4 degrees of lordosis) local angle was achieved (p = 0.04). There was a variable change in overall cervical sagittal alignment following local correction. Improvement in myelopathy was unrelated to patient age, previous surgery, or number of segments fused. Improvement in pain score was not related to correction of kyphotic angle. CONCLUSIONS: The correction of sagittal alignment may promote recovery in spinal cord function in patients with kyphotic deformity.

Anti-stroke prophylaxis--the ethics of collateral damage.

Prophylactic anticoagulation therapy with agents such as dabigatran etexilate (as an alternative to warfarin) promises substantial benefits to both patients and monitoring physicians in the treatment of those at high risk of stroke from atrial fibrillation. Such treatment has, however, one potentially lethal consequence. There is, as yet, no easily administered rapid means of reversal in instances of acute surgical emergency. The problems that may then be encountered in neurosurgical practice are discussed.

The role of transcranial Doppler ultrasound monitoring in patients with aneurysmal subarachnoid haemorrhage.

The effect of transcranial Doppler (TCD) ultrasound monitoring of vasospasm on patient management following aneurysmal subarachnoid haemorrhage (aSAH) remains unclear. We reviewed our departmental use of TCD by retrospectively analysing 152 medical records. Results of investigations and management changes, including frequency of neurological monitoring and changes in triple H therapy, were examined. TCD monitoring occurred in 87 patients (57%) by untrained neurosurgical registrars. There was high variability in the number of operators for each patient (over 50% of patients had more than two different operators), insonation protocol and monitoring duration (at least 50% of patients were monitored for fewer than seven days). TCD results influenced management in only 18 (12%) patients, while clinical deterioration or improvement dictated more than 80% of changes in triple H therapy and neurological monitoring. Prospective validation in similar neurosurgical settings is needed to justify continued usage of TCD monitoring. Formal training for operators and a standard monitoring protocol should also be considered to increase TCD utility. Prospective evaluation of TCD at our centre has recently been completed.

The effect of formal training on the clinical utility of transcranial Doppler ultrasound monitoring in patients with aneurysmal subarachnoid haemorrhage.

We have previously shown that the clinical utility of transcranial Doppler (TCD) ultrasound monitoring for vasospasm in patients with aneurysmal subarachnoid haemorrhage, as performed by untrained operators in a busy neurosurgical unit, is questionable, despite the recommendations for its use in the literature. We determined if formal training improved the utility of TCD. Twelve untrained operators and one trained operator performed a total of 206 TCD examinations. There was poor agreement of results between trained and untrained operators. For the left middle cerebral artery (MCA), right MCA, left anterior cerebral artery (ACA) and right ACA, the blood flow velocities (BFV) recorded by the trained operator were greater than those recorded by the untrained operators by a mean (95% confidence interval) of 27.7 (25.0-30.4), 24.3 (21.4-27.1), 28.2 (25.6-30.9) and 28.1 (24.9-31.1) cm/s, respectively (p<0.001 for all vessels). Greater sensitivity was observed in TCD measurements from the trained operator (100%) compared to untrained operators (40%). To improve the utility of TCD, operators should be provided with training or a professional sonographer employed.

Technical aspects of decompressive craniectomy for malignant middle cerebral artery infarction.

Decompressive craniectomy is considered a life-saving procedure for malignant middle cerebral artery territory infarction in selected patients. However, the procedure is associated with a significant risk of morbidity and mortality, and there is no universal agreement as to how this operation should be combined with optimal medical management. In this review we consider the goals of this procedure and the technical aspects which may be employed to optimise results.

Decompressive craniectomy for malignant middle cerebral artery infarction: evidence and controversies.

Malignant middle cerebral artery (MCA) infarction (MMI) is associated with a mortality rate of 80%. Decompressive craniectomy is considered a life-saving procedure for patients with this devastating condition. Preclinical and clinical data suggest that this procedure should be undertaken as early as possible, prompting increasing demand for emergency surgery. This article reviews the pathophysiology of MMI, and the experimental and clinical evidence supporting this procedure. We consider some of the controversies surrounding patient selection for this procedure and discuss the role of intracranial pressure monitoring in MMI.