C2 Dorsal Root Ganglion Research Articles

Unveiling the role of dorsal root ganglia in spasticity reduction: Insights from contralateral seventh cervical nerve cross transfer surgery.

Central nervous system (CNS) disorders, such as stroke, often lead to spasticity, which result in limb deformities and significant reduction in quality of life. Spasticity arises from disruptions in the normal functioning of cortical and descending inhibitory pathways in the brainstem, leading to abnormal muscle contractions. Contralateral seventh cervical nerve cross transfer (CC7) surgery has been proven to effectively reduce spasticity, but the specific mechanism for its effectiveness is unclear. This study aimed to investigate the changes in the dorsal root ganglia (DRG) following CC7 surgery. A comprehensive anatomical analysis was conducted through cadaveric study and magnetic resonance imaging (MRI) study, to accurately measure the regional anatomy of the C7 DRG. DRG perfusion changes were quantitatively assessed by comparing pre- and postoperative dynamic contrast-enhanced (DCE) MRI. In CC7 surgery, the C7 nerve root on the affected side is cut close to the DRG (3.6±1.0mm), while the C7 nerve root on the healthy side is cut further away from the DRG (65.0±10.0mm). MRI studies revealed that after C7 proximal neurotomy on the affected side, there was an increase in DRG volume, vascular permeability, and perfusion; after C7 distal neurotomy on the healthy side, there was a decrease in DRG volume, with no significant changes in vascular permeability and perfusion. This study provides preliminary insights into the mechanisms of spasticity reduction following CC7 surgery, indicating that changes in the DRG, such as increased vascular permeability and perfusion, could disrupt abnormal spinal γ-circuits. The resulting high-perfusion state of DRG, possibly due to heightened neuronal activity and metabolic demands, necessitating further research to verify this hypothesis.

Lateral atlanto-axial joint access using the C2 pedicle

Abstract Background Neck pain and headaches can arise from the lateral atlanto-axial (LAA) joint. This pain can be diagnosed with intra-articular injections of local anesthetic. A widely used technique for access to the lateral atlanto-axial joint uses a posterior approach, but this approach can be hazardous because of the proximity of the vertebral artery, the dural sac, and the C2 spinal nerve and dorsal root ganglion. Objective The objective was to describe and test a new technique for accessing the LAA joint that avoids structures that lie behind the joint. Interventions The new technique was described and tested for tolerance in 10 patients with unilateral suboccipital pain and tenderness over the LAA joint, along with evidence of LAA joint arthropathy on SPECT CT. The technique requires inserting a needle along a trajectory tangential to the dorsal surface of the C2 lamina. It involves obtaining a declined view of the C2 lamina and C2 pedicle. Conclusions In all cases, the C2 pedicle was easily identified and allowed the needle to pass asymptomatically underneath the neurovascular structures behind the joint. The tactile response of the lamina of C2 provided important feedback regarding needle depth caudal to the LAA joint.

A Novel Ultrasound-Guided "Three in One" Approach Plus Interfascial Plane Blocks for the Treatment of Cervicogenic Headache.

Cervicogenic headache (CEH) is a condition resulting from upper cervical spine dysfunction and associated structural and soft tissue abnormalities, significantly impacting patients' quality of life. To acquire better therapeutic results, we presented a novel ultrasound-guided "three in one" approach plus interfascial plane (IFP) blocks for the treatment of CEH. This approach allows for the modulation of C2 dorsal root ganglion (DRG), third occipital nerve (TON), and C3 medial branch with one-point puncture. Additionally, it allows for IFP blocks between the upper neck and occipital muscles within the same scanning plane. We evaluated patients diagnosed with CEH from July 2021 to December 2022 in our pain clinic. We included those who did not respond to conservative treatment and single occipital nerve block, therefore received nerve block or pulsed radiofrequency (PRF) using the "Three in One" approach plus IFP blocks. The accuracy of the ultrasound-guided C2 DRG puncture procedures was confirmed through fluoroscopy with C-arm and the sensory testing of PRF. The therapeutic effect of these interventions was assessed using the numerical rating scale (NRS) scores during telephone follow-ups at 1, 3, and 6 months. Utilizing the "Three in One" approach, a total of 5 patients diagnosed with CEH underwent nerve block plus IFP blocks, while 2 patients underwent PRF plus IFP blocks. Employing ultrasound-guided C2 DRG puncture procedures, the needle tip's correct placement was confirmed through both fluoroscopy and sensory testing of PRF. Notably, none of the cases experienced any complications associated with the approach. Subsequent follow-up assessments revealed an improvement in the NRS scores for CEH in all patients. The ultrasound-guided "Three in One" approach plus IFP blocks may be a potential effective method for the treatment of CEH.

Abstract 18058: Dorsal Root Ganglion Nerve Block Causing Reverse Takotsubo Cardiomyopathy

A 65-years-old female presents to the emergency room after C2 dorsal root ganglion nerve block for cervicogenic headaches, where intraoperatively she became hypotensive and unresponsive with sinus tachycardia to the 140s. She required brief intubation and intravenous vasopressors for resuscitation and was quickly extubated with complete neurologic recovery within hours of presentation. Her vital signs were within normal limits. She had no clinical signs of heart failure on exam. Laboratory values were within normal limits except for elevated hs- troponin which peaked at 1136ng/L. Her EKG showed nonspecific ST changes and T-wave inversion in the high lateral leads. She underwent transthoracic echocardiogram and was found to have basal to mid inferior wall and inferoseptum akinesis with reduced left ventricular ejection fraction of 35-40%. She was initially asymptomatic, but six hours after presentation developed radiating left arm pain then crushing chest and throat pain, with an uptrend in her troponins to 6539, without dynamic EKG changes. She was urgently taken to the cath lab and was found to have clean coronaries, and ventriculography was performed with findings consistent with reverse takotsubo. She was started on low dose beta blockers and ARBs with complete resolution of symptoms. Reverse takotsubo is a rare variant of takotsubo cardiomyopathy, where basal and midventricular segments of the left ventricle are akinetic, with the majority of patients recovering systolic function within months. This condition is frequently triggered by an intense trigger. To our knowledge, this is the first described case of a high-cervical nerve block precipitating takotsubo.

Quercetin Ameliorates Neuropathic Pain after Brachial Plexus Avulsion via Suppressing Oxidative Damage through Inhibition of PKC/MAPK/ NOX Pathway.

Brachial plexus avulsion (BPA) animally involves the separation of spinal nerve roots themselves and the correlative spinal cord segment, leading to formidable neuropathic pain of the upper limb. The right seventh cervical (C7) ventral and dorsal roots were avulsed to establish a neuropathic pain model in rats. After operation, rats were treated with quercetin (QCN) by intragastric administration for 1 week. The effects of QCN were evaluated using mechanical allodynia tests and biochemical assay kits. QCN treatment significantly attenuated the avulsion-provoked mechanical allodynia, elevated the levels of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx) and total antioxidant capacity (TAC) in the C7 spinal dorsal horn. In addition, QCN administration inhibited the activations of macrophages, microglia and astrocytes in the C6 dorsal root ganglion (DRG) and C6-8 spinal dorsal horn, as well as attenuated the release of purinergic 2X (P2X) receptors in C6 DRG. The molecular mechanism underlying the above alterations was found to be related to the suppression of the PKC/MAPK/NOX signal pathway. To further study the anti-oxidative effects of QCN, we applied QCN on the H2O2-induced BV-2 cells in vitro, and the results attested that QCN significantly ameliorated the H2O2-induced ROS production in BV-2 cells, inhibited the H2O2-induced activation of PKC/MAPK/NOX pathway. Our study for the first time provided evidence that QCN was able to attenuate pain hypersensitivity following the C7 spinal root avulsion in rats, and the molecular mechanisms involve the reduction of both neuro-inflammatory infiltration and oxidative stress via suppression of P2X receptors and inhibition of the activation of PKC/MAPK/NOX pathway. The results indicate that QCN is a natural compound with great promise worthy of further development into a novel therapeutic method for the treatment of BPA-induced neuropathic pain.

Ultrasound-Guided Percutaneous Peripheral Nerve Stimulation of C2 Dorsal Root Ganglion for the Treatment of Refractory Atypical Facial Pain: A Technical Report and Case Series

BackgroundChronic craniofacial pain can be difficult to manage clinically. This technical report documents the peripheral nerve stimulation of the C2 dorsal root ganglion as an effective modality to treat refractory atypical facial pain. Materials and MethodsIn this case series, three patients with chronic refractory atypical facial pain and p >50% pain relief following diagnostic C2 dorsal root ganglion blockade underwent ultrasound-guided percutaneous placement of a peripheral nerve stimulator adjacent to the C2 dorsal root ganglion. Patients were then observed clinically and monitored for improvement in symptoms and adverse events. ResultsThree patients underwent peripheral nerve stimulator placement. At follow-up, there were no reported adverse events, and all patients reported satisfactory improvement in pain. ConclusionThe neuromodulation of C2 dorsal root ganglion via ultrasound-guided percutaneously implanted peripheral nerve stimulator is a novel and potentially effective approach for the management of chronic refractory craniofacial pain.

Clinical Efficacy Evaluation of Ultrasound-Guided C2 Dorsal Root Nerve Pulsed Radiofrequency Combined with Stellate Ganglion Block in the Treatment of Cervicogenic Headache: A Retrospective Cohort Study.

To explore the therapeutic effect of C2 dorsal root ganglion pulsed radiofrequency (PRF) combined with stellate ganglion block (SGB) in patients with cervicogenic headache (CEH). We retrospectively reviewed 90 patients diagnosed with CEH who were admitted to our hospital between May 2019 and May 2022. All patients were divided into three groups (n = 30 each) according to the actual treatment method used: ultrasound-guided SGB, ultrasound-guided C2 dorsal root ganglion PRF treatment, and ultrasound-guided C2 dorsal root ganglion PRF combined with SGB treatment. Patients' pain intensity, sleep, and mood changes were assessed by statistically analyzing their pain visual analog scale (VAS), Pittsburgh Sleep Quality Inventory (PSQI), and short-form McGill Pain Questionnaire affective item scores before and after treatment. The post-treatment VAS, PSQI, and McGill scores were significantly decreased in all patients (P < 0.05), and all three scores in ultrasound-guided C2 dorsal root ganglion PRF combined with SGB were lower than those in ultrasound-guided SGB alone and ultrasound-guided C2 dorsal root ganglion PRF alone (P < 0.05). The use of ultrasound-guided C2 dorsal root ganglion PRF combined with SGB in patients with CHE is effective in alleviating pain and improving sleep, and deserves to be replicated in the clinic.

CT-Guided C2 Dorsal Root Ganglion Radiofrequency Ablation for the Treatment of Cervicogenic Headache: Case Series and Clinical Outcomes.

Cervicogenic headache is a secondary headache syndrome attributable to upper cervical spine pathology. Osteoarthritis of the lateral atlantoaxial joint with resultant C2 dorsal root ganglion irritation is an important and potentially treatable cause of cervicogenic headache. In this case series, we present 11 patients with cervicogenic headache who underwent C2 dorsal root ganglion thermal radiofrequency ablation. Radiologists should be familiar with this efficacious procedure and technical considerations to avoid complications.

Diffusion tensor imaging of the C1-C3 dorsal root ganglia and greater occipital nerve for cervicogenic headache.

BackgroundPrevious studies showed neurography and tractography of the greater occipital nerve (GON). The purpose of this study was determining diffusion tensor imaging (DTI) parameters of bilateral GONs and dorsal root ganglia (DRG) in unilateral cervicogenic headache as well as the grading value of DTI for severe headache. The correlation between DTI parameters and clinical characteristics was evaluated.MethodsThe fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values in bilateral GONs and cervical DRG (C2 and C3) were measured. Grading values for headache severity was calculated using a receiver operating characteristics curve. The correlation was analyzed with Pearson’s coefficient.ResultsThe FA values of the symptomatic side of GON and cervical DRG (C2 and C3) were significantly lower than that of the asymptomatic side (all the P < 0.001), while the ADC values were significantly higher (P = 0.003, P < 0.001, and P = 0.003, respectively). The FA value of 0.205 in C2 DRG was considered the grading parameter for headache severity with sensitivity of 0.743 and specificity of 0.999 (P < 0.001). A negative correlation and a positive correlation between the FA and ADC value of the GON and headache index (HI; r = –0.420, P = 0.037 and r = 0.531, P = 0.006, respectively) was found.ConclusionsDTI parameters in the symptomatic side of the C2 and C3 DRG and GON were significantly changed. The FA value of the C2 DRG can grade headache severity. DTI parameters of the GON significantly correlated with HI.

Pulsed Radiofrequency Ablation of the C2 Dorsal Root Ganglion Using a Posterior Approach for Treating Cervicogenic Headache: A Retrospective Chart Review.

To evaluate the efficacy and complications of C2 dorsal root ganglion (DRG) pulsed radiofrequency ablation (RFA) for cervicogenic headache (CEH) and to identify factors related to the outcome of the procedure in this retrospective analysis. Although conventional high-temperature C2 DRG RFA was effective in patients with CEH in previous studies, the effect of pulsed RFA on C2 DRG in cases of CEH has not yet been evaluated. We examined the electronic medical records of consecutive patients who underwent C2 DRG block for CEH from January 2012 to May 2018 at a pain center. Consequent C2 DRG pulsed RFA was performed for patients in whom the headache recurred after an initial period of relief 24hours after the C2 DRG block. A successful outcome was defined as at least 50% pain relief at 6months after C2 DRG pulsed RFA. We also examined variables associated with the outcome and prognostic factors of CEH. Fluoroscopy-guided C2 DRG block was performed in 114 patients with CEH. Forty-five patients received C2 DRG pulsed RFA and 40.0% among them (18/45, success group) had ≥50% pain relief after 6months. There were no post-procedure complications throughout the study period. Significantly more patients in the success group than in the failure group had a definite positive response (≥50% pain relief) to a previous C2 DRG block (P<.001). C2 DRG pulsed RFA may be an effective treatment for patients with CEH, particularly for patients who have previously experienced definite pain reduction after C2 DRG block. However, the limitations of our study design and small number of patients preclude firm conclusions.

Pulsed Radiofrequency of C2 Dorsal Root Ganglion Under Ultrasound-Guidance and CT Confirmed for Chronic Headache: Follow-Up of 20 Cases and Literature Review.

BackgroundChronic headache is common but difficult to treat. Most patients respond poorly to drugs. Nerve block is an effective treatment but has no continuous effect. The pulsed radiofrequency (PRF) technique has been shown to be effective in relieving head pain and extending the effect of nerve block.ObjectiveThe purpose of this study is to evaluate the long-term efficacy of C2 dorsal root ganglion after pulsed radiofrequency (PRF) guided by ultrasound for chronic headache.SettingThe Department of Pain Management, West China Hospital.MethodsTwenty patients who did not respond to medications and peripheral nerve blocks underwent ultrasound-guided PRF of the C2 dorsal root ganglion. The patients were followed up for 6 months. Visual analog scale (VAS) score was evaluated at 1 week, 1 month, 3 months, and 6 months. The quality of life (QOL) was assessed by Brief Pain Inventory (BPI) scores which were rated at pre-procedure and 1 month, 3 months, and 6 months after the procedure. The occurrence of complications was evaluated and reported.ResultsMean VAS scores were significantly decreased at 1 week, 1 month, 3 months and 6 months compared to the pre-procedure mean VAS score. Mean BPI scores decreased significantly at each postoperative time point compared to the preoperative baseline and low scores remained throughout the follow-up period: 45.05±3.44 at pre-procedure, 10.60 ± 2.37 at 1 weeks, 12.50 ± 2.46 at 1 month, 12.90 ± 2.62 at 3 months, and 11.63 ± 2.98 at 6 months. Mild complications occurred, including 1 case (4.7%) of transient cervicalgia (lasting for 24 hrs) and 3 cases (14.2%) of transient dizziness (lasting for 30 mins).LimitationsFirstly, it included a small sample of patients. Another is the short duration of the follow-up.ConclusionC2 PRF may be considered as an alternative treatment for chronic headache.

Fluorescently-labeled fremanezumab is distributed to sensory and autonomic ganglia and the dura but not to the brain of rats with uncompromised blood brain barrier.

BackgroundThe presence of calcitonin gene-related peptide and its receptors in multiple brain areas and peripheral tissues previously implicated in migraine initiation and its many associated symptoms raises the possibility that humanized monoclonal anti-calcitonin gene-related peptide antibodies (CGRP-mAbs) can prevent migraine by modulating neuronal behavior inside and outside the brain. Critical to our ability to conduct a fair discussion over the mechanisms of action of CGRP-mAbs in migraine prevention is data generation that determines which of the many possible peripheral and central sites are accessible to these antibodies – a question raised frequently due to their large size.Material and methodsRats with uncompromised and compromised blood-brain barrier (BBB) were injected with Alexa Fluor 594-conjugated fremanezumab (Frema594), sacrificed 4 h or 7 d later, and relevant tissues were examined for the presence of Frema594.ResultsIn rats with uncompromised BBB, Frema594 was similarly observed at 4 h and 7 d in the dura, dural blood vessels, trigeminal ganglion, C2 dorsal root ganglion, the parasympathetic sphenopalatine ganglion and the sympathetic superior cervical ganglion but not in the spinal trigeminal nucleus, thalamus, hypothalamus or cortex. In rats with compromised BBB, Frema594 was detected in the cortex (100 µm surrounding the compromised BBB site) 4 h but not 7 d after injections.DiscussionOur inability to detect fluorescent (CGRP-mAbs) in the brain supports the conclusion that CGRP-mAbs prevent the headache phase of migraine by acting mostly, if not exclusively, outside the brain as the amount of CGRP-mAbs that enters the brain (if any) is too small to be physiologically meaningful.

Ultrasound Scan of the Occipital and Upper Cervical Region

The sonoanatomical knowledge of the upper cervical and occipital region is critical for the identification of structures involved in the pathophysiology of cervicogenic headache and neck pain. We propose a systematic caudo-cranial ultrasound scan using a paramedial transverse view. The first relevant structure to identify is the Obliquus Capitis Inferior Muscle (OCIM) that in turn will allow us to locate the Great Occipital Nerve (GON), the C1-C2 joint, the C2 dorsal root ganglion, medial to the joint, and the Vertebral Artery, lateral to the joint. Sonogram 1 demonstrates the great occipital nerve (GON) between the seminspinalis capitus muscle (SMCEM) and obliquus Capitis Inferior Muscle (OCIM) and the C1-C2 joint. Aligning the transducer obliquely along the long axis of the OCIM, may allow for better visualization of the muscle. With a cranial displacement of the probe, one can identify the posterior arch of C1 and the vertebral artery as it transverses from lateral to medial crossing the medial posterior aspect of the atlanto-occipital joint (sonograms 2 and 3). Finally, with more cranial scan, one can identify the occipital bone and the occipital artery near the distal branches of the greater occipital nerve and third occipital nerve more medially (Sonogram 4). With continued cranial scanning the GON will be more superficial as it pierces the trapezius aponeurosis.

CT-Guided Block and Radiofrequency Ablation of the C2 Dorsal Root Ganglion for Cervicogenic Headache.

The purpose of this report is to describe the technical aspects of CT-guided C2 dorsal root ganglion diagnostic block and radiofrequency ablation for refractory cervicogenic headache. CT guidance allows precise and safe positioning of a needle adjacent to the C2 dorsal root ganglion. At-risk neural and vascular structures can be avoided with CT, and it can provide a thorough understanding of upper cervical neuroanatomy.

Brachial Artery Vasospasm Caused by Cervical Dorsal Root Ganglion Degeneration After Subarachnoid Hemorrhage: An Experimental Study

Subarachnoid hemorrhage (SAH) may lead to vasospasm in various vessels. The cervical nerves have a vasodilatory effect on the upper extremity arteries. The aim of this study was to investigate if there is a relationship between C6 dorsal root ganglion (DRG) degeneration and brachial artery (BA) vasospasm after spinal SAH. This experimental study was conducted on 23 rabbits. The animals were divided into 3 groups: control (n= 5), SHAM (n= 5), and study group (n= 13). One cubic centimeter (cc) of serum saline was injected into the cisterna magna of animals of the SHAM group; the same procedure was performed by 1 cc of homologous blood in the study group. Degenerated neuron densities (DNDs) of DRGs (n/mm3) at C6 levels and BA vasospasm indexes (VSI; wall surface/lumen surface) of all animals were determined and results were analyzed statistically. Mean VSI values of BAs and DNDs of C6DRGs of the control, SHAM, and study groups were estimated as 10 ± 3/1.12 ± 0.11 n/mm3, 34 ± 9/1.27 ± 0.24 n/mm3, and 1031 ± 145/2.93 ± 0.78 n/mm3, respectively. Mean DNDs and VSI values were statistically significantly different between the control and study groups (P < 0.0001). C6DRG degeneration may be considered as an important factor in the etiopathogenesis of severe BA vasospasm after SAH.

Pulsed radiofrequency of the C2 dorsal root ganglion and epidural steroid injections for cervicogenic headache.

Cervicogenic headache (CEH) is characterized by unilateral headache symptoms referred to the head from the cervical spine. Few methods have addressed long-term pain relief for CEH. This study was undertaken to evaluate pain control and quality of life after pulsed radiofrequency (PRF) for the C2 dorsal root ganglion and epidural steroid injections (ESI) for CEH. This was a case-control study. One hundred thirty-nine patients suffering from CEH were enrolled in this study. Of these patients, 87 CEH patients underwent PRF for the C2 dorsal root ganglion and ESI therapy, and 52 CEH patients only underwent ESI therapy. Quality of life and pain control were measured with the European Organization for Research and Treatment of Cancer (EORTC) Quality-of-Life Questionnaire (QLQ-C30) and Izbicki pain scores. Kaplan-Meier curve was used to evaluate the efficacy of the treatment in the groups. Before therapy, the median of Izbicki pain score in PRF+ESI group and ESI group was 78.5 and 72.5, respectively (p = 0.574). After 2year follow-up, significant reduction was found in the two groups (11.25 versus 40.00, p < 0.001). The two groups demonstrated an equal distribution of age and gender (p > 0.05). SF (68.52 ± 21.50 versus 50.63 ± 15.42), PF (70.61 ± 29.47 versus 47.87 ± 21.53), RF (52.04 ± 17.92 versus 38.13 ± 24.07), EF (61.17 ± 28.41 versus 43.52 ± 25.48), CF (55.36 ± 19.82 versus 46.82 ± 23.54), and QL (59.31 ± 27.44 versus 50.73 ± 21.90) were significantly higher in PRF+ESI group than in ESI group. Kaplan-Meier curve showed that the probability of treatment success in PRF+ESI group was higher than that in ESI group (median pain relief: ESI group, 4months; PRF+ESI group, 8months) (Log-Rank test, p < 0. 001). There was no serious side effect in this study. The combination of PRF for the C2 dorsal root ganglion and ESI is a relatively safe therapy for CEH. This technique not only provides the sustained relief of pain symptom but improves the quality of life in patients with CEH.

Pulsed radiofrequency of C2 dorsal root ganglion in patients with tinnitus.

The second cervical nerve ganglion bar appears to be beneficial in patients with treatment safe tinnitus. As far as anyone is concerned, the viability of this methodology in patients with tinnitus has never been evaluated. The point of this investigation was to decide the adequacy of beat radiofrequency of C2 dorsal root ganglion for treating patients with tinnitus, and all the more explicitly, to survey the parameters related with a long haul advantage so as to improve understanding determination. Subjects were 61 back to back patients who went to our facility from October 2016 to October 2018 for discussions on their tinnitus that endured for one month or more and were treated with beat radiofrequency of C2 dorsal root ganglion. Clinical information structure these patients were explored reflectively. An autonomous spectator assesses the long haul impact of the treatment by phone meet. In a partner of patients with tinnitus that persevered for one month or more, 25% of the patients reacted with a decrease of their tinnitus after a beat radiofrequency of C2 dorsal root ganglion. The vast majority of the patients with a positive reaction appraised the impact of treatment as a decrease of half or more. At 13.5 months, half of at first effective treated patients still encountered an advantage. Unfavorable occasions of the beat radiofrequency of C2 dorsal root ganglion at 7 weeks of follow-up were an expansion of the force of the tinnitus in 7% of the patients. In patients with an age under 43 years at the time tinnitus began, 45% of them had a decrease of their tinnitus at 7 weeks following treatment with beat radiofrequency of C2 dorsal root ganglion. Pulsed radiofrequency of C2 dorsal root ganglion can lessen the power of tinnitus extensively and for the long haul in 25% of the patients with tinnitus without genuine antagonistic impacts. We prescribe this treatment in patients with an age under 43 years at the time tinnitus began.

Physiologic facet capsule stretch can induce pain & upregulate matrix metalloproteinase-3 in the dorsal root ganglia when preceded by a physiological mechanical or nonpainful chemical exposure

BackgroundNeck pain from cervical facet loading is common and induces inflammation and upregulation of nerve growth factor (NGF) that can sensitize the joint afferents. Yet, the mechanisms by which these occur and whether afferents can be pre-conditioned by certain nonpainful stimuli are unknown. This study tested the hypothesis that a nonpainful mechanical or chemical insult predisposes a facet joint to generate pain after a later exposure to typically nonpainful distraction. MethodsRats were exposed to either a nonpainful distraction or an intra-articular subthreshold dose of NGF followed by a nonpainful distraction two days later. Mechanical hyperalgesia was measured daily and C6 dorsal root ganglia (DRG) tissue was assayed for NGF and matrix metalloproteinase-3 (MMP-3) expression on day 7. FindingsThe second distraction increased joint displacement and strains compared to its first application (p = 0.0011). None of the initial exposures altered behavioral sensitivity in either of the groups being pre-conditioned or in controls; but, sensitivity was established in both groups receiving a second distraction within one day that lasted until day 7 (p < 0.024). NGF expression in the DRG was increased in both groups undergoing a pre-conditioning exposure (p < 0.0232). Similar findings were observed for MMP-3 expression, with a pre-conditioning exposure increasing levels after an otherwise nonpainful facet distraction. InterpretationThese findings suggest that nonpainful insults to the facet joint, when combined, can generate painful outcomes, possibly mediated by upregulation of MMP-3 and mature NGF.

Practical considerations of linear accelerator-based frameless extracranial radiosurgery for treatment of occipital neuralgia for nonsurgical candidates.

Occipital neuralgia generally responds to medical or invasive procedures. Repeated invasive procedures generate increasing complications and are often contraindicated. Stereotactic radiosurgery (SRS) has not been reported as a treatment option largely due to the extracranial nature of the target as opposed to the similar, more established trigeminal neuralgia. A dedicated phantom study was conducted to determine the optimum imaging studies, fusion matrices, and treatment planning parameters to target the C2 dorsal root ganglion which forms the occipital nerve. The conditions created from the phantom were applied to a patient with medically and surgically refractory occipital neuralgia. A dose of 80 Gy in one fraction was prescribed to the C2 occipital dorsal root ganglion. The phantom study resulted in a treatment achieved with an average translational magnitude of correction of 1.35 mm with an acceptable tolerance of 0.5 mm and an average rotational magnitude of correction of 0.4° with an acceptable tolerance of 1.0°. For the patient, the spinal cord was 12.0 mm at its closest distance to the isocenter and received a maximum dose of 3.36 Gy, a dose to 0.35 cc of 1.84 Gy, and a dose to 1.2 cc of 0.79 Gy. The brain maximum dose was 2.20 Gy. Treatment time was 59 min for 18, 323 MUs. Imaging was performed prior to each arc delivery resulting in 21 imaging sessions. The average deviation magnitude requiring a positional or rotational correction was 0.96 ± 0.25 mm, 0.8 ± 0.41°, whereas the average deviation magnitude deemed within tolerance was 0.41 ± 0.12 mm, 0.57 ± 0.28°. Dedicated quality assurance of the treatment planning and delivery is necessary for safe and accurate SRS to the cervical spine dorsal root ganglion. With additional prospective study, linear accelerator‐based frameless radiosurgery can provide an accurate, noninvasive alternative for treating occipital neuralgia where an invasive procedure is contraindicated.

Repeat RF Ablation of C2 and Third Occipital Nerves for Recurrent Occipital Neuralgia and Cervicogenic Headaches

Objective: To address the degree and duration of pain relief from recurrent cervicogenic headaches and/or occipital neuralgia following retreatment with radiofrequency ablation of the C2 dorsal root ganglion and/or third occipital nerves; to review outcomes including duration and degree of pain relief; to evaluate procedure’s complication rate and patient’s willingness to repeat the procedure; to compare effectiveness of the most recent RF ablation to patient’s first RF ablation. Methods: This is a single-center retrospective observational study of 23 patients with recurrent cervicogenic headaches and/or occipital neuralgia treated with repeated RF ablation of the C2 dorsal root ganglion and/or third occipital nerves. All patients receiving treatment from January 2010 to July 2014 are included in this single site retrospective study. This is an IRB approved medical chart review study. Results: 22 of 23 patients underwent follow-up. An average of 86.5% of participants reported pain relief on average of 25.4 weeks at time of follow-up. 41% reported side effects including suboccipital hyperesthesia and/or ear discomfort, 95% reported willingness to repeat the procedure again if severe symptoms recurred, 59% of patients reported the most recent RF ablation had the same results as the first, 32% reported the most recent RF was the most effective, and 9% reported that the first RF was the most effective. Conclusion: Repeated RF ablation is a feasible option for recurrent cervicogenic headaches and/or occipital neuralgia. Effectiveness of repeat intervention is the same or better than the first ablation. Though there was a higher likelihood of side effects including suboccipital neuralgia and/or ear discomfort on repeat treatment, the side effects were generally well tolerated.