Ultrasound-Guided Proximal and Distal Tarsal Decompression: An Analysis of Pressures in the Tarsal, Medial Plantar, and Lateral Plantar Tunnels.

Objectives. To analyze the reliability of measurements of tarsal tunnel and medial and lateral plantar tunnel pressures before and after ultrasound-guided release. Measurements taken were guided by ultrasound to improve reliability. This novel approach may help surgeons make surgical decisions. The second objective was to confirm that decompression using ultrasound-guided surgery as previously described by the authors is technically effective, reducing pressure to the tarsal and medial and lateral plantar tunnels. Methods. The study included 23 patients with symptoms compatible with idiopathic tarsal tunnel syndrome (TTS). The first step was to measure intracompartmental pressure of the tarsal tunnel, medial plantar tunnel, and lateral plantar tunnel preoperatively. The second step was ultrasound-guided decompression of the tibial nerve and its branches. Subsequently, pressure was measured again immediately after decompression in the 3 tunnels. Results. After surgery, the mean values significantly dropped to normal values. This represents a validation of effective decompression of the tibial nerve and its branches in TTS with ultra-minimally invasive surgery. Conclusions. The ultrasound-guided surgical technique to release the tibial nerve and its branches is effective, significantly reducing pressure in the tunnels and, thereby, decompressing the nerves.Level of evidence: Level IV.

Patient-reported outcomes in the setting of a randomized control trial on the efficacy of transcutaneous stimulation of the posterior tibial nerve compared to percutaneous stimulation in idiopathic overactive bladder syndrome.

AIM: To compare the efficacy of transcutaneous tibial nerve stimulation (TTNS) with percutaneous tibial nerve stimulation (PTNS) regarding patient-reported outcomes measures, specifically quality-of-life (QoL) improvement and patient's treatment benefit, on symptoms associated with overactive bladder (OAB). METHODS: Patients with refractory OAB symptoms and detrusor overactivity were randomized to receive TTNS or PTNS for 12 weeks. Data from self-report OAB questionnaire short form (q-SF) and incontinence (I)-QoL questionnaires were collected pretreatment and at Weeks 6 and 12. Patients' self-perceived benefits on symptoms (treatment benefit scale, TBS) were also gathered. Mean change in scores within and between groups were estimated. RESULTS: Sixty-eight adult patients (67.6% women) were included in the intention to treat analysis. Of those, 61 completed all questionnaires and were analyzed as per protocol. Statistically significant improvements in OAB-q-SF and I-QoL between baseline and end-of-treatment scores were observed in both TTNS and PTNS groups (p < .001), being the differences much higher than the minimal important difference in both questionnaires. The scores of the OAB-q-SF scales (symptoms bother and health-related QoL) showed no statistically significant differences between the two groups. Similarly, the differences regarding the I-QoL questionnaire were statistically nonsignificant either (p = .607). When assessing the treatment benefit on symptoms, TBS responses between groups showed no statistical differences. CONCLUSION: A significant improvement of QoL was observed in both TTNS and PTNS groups. However, no patient-reported outcomes measures scores support a difference between the two groups. Therefore, these findings along with TTNS ease of application and less invasiveness may lead to an increased indication of this technique for OAB.

Efficacy of transcutaneous posterior tibial nerve stimulation in children with functional voiding disorders.

AIMS: To assess the efficacy of transcutaneous posterior tibial nerve stimulation (TPTNS) on functional voiding disorder (FVD) and investigate the utility of urine biomarkers (UBs: nerve growth factor, transforming growth factor-beta 1, and tissue inhibitor of metalloproteinases 2) in diagnosis and follow-up. METHODS: A total of 44 children were included to this randomized controlled trial prospectively. After randomization, 20 of 30 children with storage phase dysfunction those were unresponsive or noncompliant to medical treatment received TPTNS treatment (test group) and 10 children underwent TPTNS with no current (sham group) for 12 weeks. Fourteen healthy children constituted the nonsymptomatic group. UB levels, dysfunctional voiding and incontinence scoring system (DVISS), voiding diary, and quality of life (QoL) scores were assessed before and after treatment in the treatment groups. RESULTS: QoL scores, overall and day-time DVISS scores were significantly decreased in both sham and test groups (p < 0.05). In addition to these findings, the frequency of incontinence and urgency episodes were also significantly reduced (p < 0.05) in the TPTNS treatment group. This effect in the test group was still valid 2 years after intervention. There was no significant difference in UBs measurements between treatment and nonsymptomatic groups and between pretreatment and posttreatment measurements of test and sham groups. CONCLUSIONS: TPTNS is an efficient minimally invasive treatment in children with FVD who do not respond to medical treatment. TPTNS provides a significant improvement on episodes of frequency, episodes of incontinence, overall and day-time DVISS scores, and QoL scores. The effectiveness of treatment continues even at the end of the second year of intervention. UBs were not found to be predictive in terms of diagnosis and evaluating the treatment response.

The Effect of Total Hip Arthroplasty on the Sciatic Nerve: an Electrodiagnostic Evidence Study.

OBJECTIVE: Objectively evaluate the incidence of sciatic nerve injury after a total hip arthroplasty (THA) performed through a posterolateral approach. METHODS: Patients scheduled to undergo THA were evaluated preoperatively and postoperatively with electrophysiologic studies, the Western Ontario and McMaster Universities Osteoarthritis index (WOMAC) questionnaire and other methods described in the study. Patients older than 21 years with any of the following preoperative diagnoses: primary or secondary osteoarthritis, aseptic avascular necrosis, rheumatoid arthritis, and posttraumatic arthritis were included. Variables used for analysis were sex, age, and body mass index (BMI). The Mann-Whitney U and Wilcoxon tests and, Pearson and Spearman correlation statistics were used for analysis of categorical and continuous data respectively. RESULTS: Electrodiagnostic data showed alterations in 17 patients (70.8%). No signs of sciatic nerve injury. The mean preoperative and postoperative WOMAC scores were 40 and 74, respectively (p = 0.0001). Statistical differences were noted in sural sensory amplitude (SSA) and distal amplitude of the tibialis motor nerve in the female group (p=0.007; p=0.036, respectively). The SSA also demonstrated differences in the obese group (p=0.008). In terms of age, both the SSA (Pearson p=0.010 and Spearman p=0.024) and the proximal latency of the peroneal motor nerve (Pearson p=0.026 and Spearman p=0.046) demonstrated a decrease in amplitude and an increase in latency that was inversely related with age. CONCLUSION: According to our subclinical electrophysiological findings, surgeons that use the posterolateral approach in THA procedures must be conscious of the sciatic nerve's vulnerability to reduce possible clinical complications.

MScanFit motor unit number estimation and muscle velocity recovery cycle recordings in diabetic polyneuropathy.

OBJECTIVE: Motor Unit Number Estimation (MUNE) methods may be valuable in tracking motor unit loss in diabetic polyneuropathy (DPN). Muscle Velocity Recovery Cycles (MVRCs) provide information about muscle membrane properties. This study aimed to examine the utility of the MScanFit MUNE in detecting motor unit loss and to test whether the MVRCs could improve understanding of DPN pathophysiology. METHODS: Seventy-nine type-2 diabetic patients were compared to 32 control subjects. All participants were examined with MScanFit MUNE and MVRCs in anterior tibial muscle. Lower limb nerve conduction studies (NCS) in peroneal, tibial and sural nerves were applied to diagnose large fiber neuropathy. RESULTS: NCS confirmed DPN for 47 patients (DPN + ), with 32 not showing DPN (DPN-). MScanFit showed significantly decreased MUNE values and increased motor unit sizes, when comparing DPN + patients with controls (MUNE = 71.3 ± 4.7 vs 122.7 ± 3.8), and also when comparing DPN- patients (MUNE = 103.2 ± 5.1) with controls. MVRCs did not differ between groups. CONCLUSIONS: MScanFit is more sensitive in showing motor unit loss than NCS in type-2 diabetic patients, whereas MVRCs do not provide additional information. SIGNIFICANCE: The MScanFit results suggest that motor changes are seen as early as sensory, and the role of axonal membrane properties in DPN pathophysiology should be revisited.

Detecting peripheral motor nervous system involvement in chronic spinal cord injury using two novel methods: MScanFit MUNE and muscle velocity recovery cycles.

OBJECTIVE: To examine the peripheral nervous system (PNS) in spinal cord injured (SCI) patients using two novel methods: (1) MScanFit MUNE; a motor unit number estimation method detecting motor unit loss and (2) muscle velocity recovery cycles (MVRCs) measuring muscle membrane properties which has previously shown depolarization of the muscle membrane in denervated muscles. METHODS: Thirty chronic SCI patients (lesion above Th10) and twenty-five gender -and age matched healthy controls (HC) were examined. MScanFit was recorded from peroneal nerve to anterior tibial muscle (TA) and tibial nerve to abductor hallucis muscle after excluding localized mononeuropathies. MVRCs were recorded from TA. RESULTS: Nerve conduction studies showed mononeuropathy in 8 patients (27%) (sciatic (2), -or peroneal nerve (6)). SCI patients had in average reduced motor unit number compared with HC and prolonged muscle refractory period and reduced supernormality. SIGNIFICANCE: A high prevalence of nerve lesion and a diffuse affection of the PNS following SCI are highly relevant findings that should be accounted for when planning neurorehabilitation for persons living with SCI.

Treatment patterns and costs among patients with OAB treated with combination oral therapy, sacral nerve stimulation, percutaneous tibial nerve stimulation, or onabotulinumtoxinA in the United States.

INTRODUCTION: Treatment patterns and costs were characterized among patients with overactive bladder (OAB) receiving later-line target therapies (combination mirabegron/antimuscarinic, sacral nerve stimulation [SNS], percutaneous tibial nerve stimulation [PTNS], or onabotulinumtoxinA). METHODS: In a retrospective cohort study using 2013 to 2017 MarketScan databases, two partially overlapping cohorts of adults with OAB ("IPT cohort": patients with incident OAB pharmacotherapy use; "ITT cohort," incident target therapy) with continuous enrollment were identified; first use was index. Demographic characteristics, treatment patterns and costs over the 24-month follow-up period were summarized. Crude mean (standard deviation [SD]) OAB-specific (assessed by OAB diagnostic code or pharmaceutical dispensation record) costs were estimated according to target therapy. RESULTS: The IPT cohort comprised 54 066 individuals (mean [SD] age 58.5 [15.0] years; 76% female), the ITT cohort, 1662 individuals (mean [SD] age 62.8 [14.9] years; 83% female). Seventeen percent of the IPT cohort were treated with subsequent line(s) of therapy after index therapy; among those, 73% received antimuscarinics, 23% mirabegron, and 1.4% a target therapy. For the ITT cohort, 32% were initially treated with SNS, 27% with onabotulinumtoxinA, 26% with combination mirabegron/antimuscarinic, and 15% with PTNS. Subsequently, one-third of this cohort received additional therapies. Mean (SD) costs were lowest among patients receiving index therapy PTNS ($6959 [$7533]) and highest for SNS ($29 702 [$26 802]). CONCLUSIONS: Costs for SNS over 24 months are substantially higher than other treatments. A treatment patterns analysis indicates that oral therapies predominate; first-line combination therapy is common in the ITT cohort and uptake of oral therapy after procedural options is substantial.

Tibial Nerve Dysfunction Associated With Operatively Treated Talar Neck Fractures.

OBJECTIVE: To investigate the presence of tibial nerve dysfunction (TND) in operatively treated talar neck fractures. DESIGN: Retrospective chart review. SETTING: Urban Level-1 trauma center. PATIENTS: Sixty-four patients for a total of 65 talar neck fractures treated with open reduction and internal fixation between January 1, 2014, and May 1, 2018. MAIN OUTCOME MEASURES: Incidence of TND. RESULTS: Evidence of TND was documented in 20 of 65 cases (30.8%) of talar neck fractures. There were no cases of TND associated with Hawkins I fractures, but TND was found in 7 of 32 Hawkins II fractures (21.9%), 10 of 24 Hawkins III fractures (41.7%), and 3 of 5 Hawkins IV fractures (60%). TND was reported in 11 of 19 open talar neck fractures (57.9%) (P = 0.002). TND was associated with tibiotalar dislocation (P = 0.017) but not subtalar dislocation (P = 0.17). TND did not occur in the absence of subtalar subluxation/dislocation. Of 18, a total of 6 (33.3%) reported partial recovery, and 6 (33.3%) reported full recovery within 6 months of the initial injury. By 12 months, of the 18, 8 (44.4%) reported partial recovery and 7 (38.9%) reported full recovery. CONCLUSION: The tibial nerve and its distal branches are at risk of injury in the setting of displaced talar neck fracture, tibiotalar subluxation/dislocation, and open talar neck fracture with increasing risk among those with a higher Hawkins grade. LEVEL OF EVIDENCE: Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Superficial peroneal neuromodulation of nonobstructive urinary retention in cats.

AIMS: To determine if superficial peroneal nerve stimulation (SPNS) can improve nonobstructive urinary retention (NOUR). METHODS: In α-chloralose anesthetized cats, NOUR was induced by repetitive application (4-16 times) of 30-minute tibial nerve stimulation (TNS: 5 Hz frequency, 0.2 ms pulse width) at 4 to 6 times threshold intensity (T) for inducing toe twitches. SPNS (1 Hz, 0.2 ms) at 2 to 4 times threshold intensity (T) for inducing posterior thigh muscle contractions was applied either continuously (SPNSc) during a cystometrogram (CMG) or during voiding (SPNSv) by a surgically implanted cuff electrode or by skin surface electrodes to determine if the stimulation reduced NOUR induced by prolonged TNS. RESULTS: During control CMGs, efficient (86.4% ± 5.5%) voiding occurred with a postvoid residual (PVR) volume equal to 14.9% ± 6.2% of control bladder capacity. NOUR elicited by prolonged TNS significantly (P < .05) increased bladder capacity to 168.6% ± 15.5% of control, reduced voiding efficiency to 30.4% ± 4.8%, and increased PVR to 109% ± 9.2% of control. Using the implanted cuff electrode, SPNSc and SPNSv significantly (P < .05) increased voiding efficiency to 66.7% ± 7.4% and 65.0% ± 5.9%, respectively, and reduced PVR to 52.2% ± 11.4% and 64.3% ± 11.6%, respectively. SPNSc but not SPNSv significantly (P < .05) reduced bladder capacity to 133.4% ± 15% of control. Transcutaneous SPNSv but not SPNSc also significantly (P < .05) reversed the TNS-induced NOUR responses. CONCLUSIONS: This study shows that SPNS is effective in reversing NOUR induced by prolonged TNS. Transcutaneous SPNS provides the opportunity to develop a noninvasive neuromodulation therapy for NOUR to treat more patients than current sacral neuromodulation therapy.

Multifocal, hypoechogenic nerve thickening in Cerebrotendinous Xanthomatosis.

OBJECTIVE: To characterize peripheral nerve morphology in cerebrotendinous xanthomatosis (CTX) patients using high-resolution ultrasound (HRUS) in vivo. We hypothesized that nerve enlargements might be present in CTX as a result of accumulation of abnormal lipids with deposition also in peripheral nerves. METHODS: Four CTX patients were examined using HRUS to assess morphological abnormalities of peripheral nerves as well as cervical nerve roots 5 and 6. RESULTS: HRUS revealed mild to moderate, hypoechogenic thickening of sensorimotor nerves (ulnar nerve in 1/4, tibial nerve in 3/4, median nerve 4/4 patients) as well as mild enlargement of pure sensory nerves (sural nerve in 2/3, superficial FN in 2/4 patients). The vagal nerve was moderately enlarged in one patient, cervical roots showed moderate enlargements of C5 in two patients, one of which also showing thickening of C6 as well as in another patient. UPSS score was slightly to moderately abnormal in all patients. The Homogeneity score was not increased suggesting regional to inhomogeneous nerve enlargement. CONCLUSIONS: HRUS shows multifocal, hypoechogenic nerve thickening of peripheral nerves and nerve roots in CTX. SIGNIFICANCE: HRUS might serve as a valuable, additive and non-invasive bedside tool to assess peripheral nerve morphology in future clinical studies on CTX patients.

Contemporary Patterns of Third-line Treatments for Privately Insured Individuals With Overactive Bladder in the United States.

OBJECTIVE: To evaluate utilization of third-line overactive bladder (OAB) treatments including percutaneous tibial nerve stimulation (PTNS), sacral nerve stimulation (SNS), and intradetrusor botulinum toxin A (BTX) among privately insured patients and examine factors associated with their use. MATERIALS AND METHODS: Using MarketScan claims (2015-2017), we identified patients who underwent third-line OAB treatments based on procedure codes. Factors of interest included location, age, health plan, among others. We fit multivariable logistic regression models to estimate associations between pertinent factors with receipt of PTNS and SNS relative to BTX and associations between provider type and practice location with each treatment modality. RESULTS: We identified 7383 patients (mean age 50.9) in our cohort. SNS was used most frequently (n = 3602, 48.8%), while PTNS was used least frequently (n = 955, 12.9%). PTNS patients were more likely to reside in metropolitan areas (vs BTX: OR 1.6, 95%CI 1.3-2.1; vs SNS: OR 2.2, 95%CI 1.7-2.8), be aged 55 years or older (vs BTX: 54% vs 47%, OR 1.6, 95%CI 1.2-2.1; vs SNS: 54% vs 45%, OR 1.6, 95%CI 1.2-2.0), and be covered under a health maintenance organization (vs BTX: 17% vs 10%; vs SNS: 17% vs 10%, P <.01). Urologists were most likely to perform SNS, and gynecologists were most likely to perform BTX. 91% of PTNS procedures were performed in office settings. CONCLUSION: Among patients receiving third-line OAB treatment, PTNS was used infrequently. PTNS utilization was concentrated within urban areas, and among older patients and those covered by cost-conscious health maintenance organizations.

Rehabilitation strategies for low anterior resection syndrome. A systematic review.

OBJECTIVE: To summarize the evidence in the literature about rehabilitative treatments that reduce low anterior resection syndrome (LARS) symptoms in patients who underwent surgery for colorectal cancer. METHODS: We have search in PubMed, Cochrane Central Register of Controlled Trials, Cumulative Index of Nursing and Allied Health and Scopus databases. Studies selected were limited to those including only patient undergone low rectal resection with sphincter preservation and with pre-post assessment with a LARS score. Five articles fit the criteria. RESULTS: The percutaneous tibial nerve stimulation demonstrated moderate results and sacral nerve stimulation was found to be the best treatment with greater symptom improvement. Only one study considered sexual and urinary problems in the outcomes assessment. CONCLUSIONS: In clinical practice patients should evaluate with the LARS and other score for evaluation of urinary and sexual problems. Future research must be implemented with higher quality studies to identify the least invasive and most effective treatment/s.

Application value of conventional ultrasound and real-time shear wave elastography in patients with type 2 diabetic polyneuropathy.

PURPOSE: To explore the application value of conventional ultrasound and real-time shear wave elastography (SWE) to the tibial nerve (TN) and the common peroneal nerve (CPN) in diabetic peripheral neuropathy (DPN). MATERIALS AND METHODS: Thirty-three healthy volunteers, 33 diabetic patients without DPN, and 30 diabetic patients with DPN were enrolled in this study. The anteroposterior diameter (APD), the cross-sectional area (CSA), and the perimeter of the TN and the CPN were measured by conventional ultrasound, and the stiffness of the nerves was measured by SWE. RESULTS: The conventional ultrasound parameters and stiffness of the TN in patients with DPN were significantly larger than those of the other two groups (P < 0.01). The conventional ultrasound parameters of the CPN were significantly higher in patients with DPN than in the other two groups (P < 0.01).The patients with DPN demonstrated a greater stiffness of the CPN compared to the control group (P < 0.05). The comparison of all parameters for the left and right TNs and CPNs among the three groups showed no significant difference. The area under the curve (AUC) of TN stiffness for the diagnosis of DPN was significantly greater than that of conventional ultrasound parameters. CONCLUSION: The conventional ultrasound parameters and the stiffness of the TN and the CPN were significantly higher in patients with DPN. The stiffness of the TN could better diagnose DPN than conventional ultrasound parameters. In short, conventional ultrasound and SWE of nerves are of good application value in the diagnosis of DPN.

Different electrode positioning for transcutaneous electrical nerve stimulation in the treatment of urgency in women: a study protocol for a randomized controlled clinical trial.

BACKGROUND: Urgency is a complaint of sudden, compelling desire to pass urine, which is difficult to defer, caused by involuntary contraction of the detrusor muscle during the bladder-filling stage. To enable detrusor inhibition, electrotherapy resources such as transcutaneous tibial nerve stimulation (TTNS) and parasacral transcutaneous electrical stimulation (PTES) have been used. The objective this study is to publish the study protocol that aims to investigate whether urgency decreases after treatment with both of the techniques. METHODS: This randomized controlled clinical trial will include 99 women, aged more than 18 years old, with urgency (score ≥ 8 in the Overactive Bladder-Validated 8-Question Awareness Tool [OAB-V8]). Women will be randomly allocated into three groups: TTNS, PTES, and placebo. The following questionnaires will be applied: the Anamnesis Record, the Incontinence Questionnaire Overactive Bladder, the King's Health Questionnaire, the 24-Hour Voiding Diary, and the OAB-V8, at four different time points: at baseline prior to the first session, at the 6th session, the 12th session and at follow-up. The current used for the transcutaneous electrical stimulation will be a symmetrical balanced biphasic pulsed current, for 12 sessions, twice a week, for 20 minutes. Qualitative variables will be displayed as frequency and percentage, quantitative variables as mean and standard deviation. Comparison of urgency severity among groups will be performed with a repeated measures ANOVA, considering the effect of the three groups and the four evaluations, and interactions among them. DISCUSSION: The present study aims to contribute evidence for a more in-depth discussion on electrode positioning for electrostimulation used in urgency treatment. It should be emphasized that, based on the possibility of confirming the hypothesis that urgency will decrease in a similar way after both treatments (TTNS and PTES), the PTES will be used as an option for positioning the electrodes alternatively to the tibial nerve region in special populations, such as amputees or people with severe lower limb sensory impairment. TRIAL REGISTRATION: Brazilian Registry of Clinical Trials (ReBEC) ID: RBR-9rf33n, date of registration: 17 May 2018.

Comparing the Efficacy of OnabotulinumtoxinA, Sacral Neuromodulation, and Peripheral Tibial Nerve Stimulation as Third Line Treatment for the Management of Overactive Bladder Symptoms in Adults: Systematic Review and Network Meta-Analysis.

The American Urological Association guidelines for the management of non-neurogenic overactive bladder (OAB) recommend the use of OnabotulinumtoxinA, sacral neuromodulation (SNM), and peripheral tibial nerve stimulation (PTNS) as third line treatment options with no treatment hierarchy. The current study used network meta-analysis to compare the efficacy of these three modalities for managing adult OAB syndrome. We performed systematic literature searches of several databases from January 1995 to September 2019 with language restricted to English. All randomized control trials that compared any dose of OnabotulinumtoxinA, SNM, and PTNS with each other or a placebo for the management of adult OAB were included in the study. Overall, 17 randomized control trials, with a follow up of 3-6 months in the predominance of trials (range 1.5-24 months), were included for analysis. For each trial outcome, the results were reported as an average number of episodes of the outcome at baseline. Compared with the placebo, all three treatments were more efficacious for the selected outcome parameters. OnabotulinumtoxinA resulted in a higher number of complications, including urinary tract infection and urine retention. Compared with OnabotulinumtoxinA and PTNS, SNM resulted in the greatest reduction in urinary incontinence episodes and voiding frequency. However, comparison of their long-term efficacy was lacking. Further studies on the long-term effectiveness of the three treatment options, with standardized questionnaires and parameters are warranted.

Neuromuscular ultrasound for taxane peripheral neuropathy in breast cancer.

BACKGROUND: Our study aim was to evaluate neuromuscular ultrasound (NMUS) for the assessment of taxane chemotherapy-induced peripheral neuropathy (CIPN), the dose-limiting toxicity of this agent. METHODS: This cross-sectional study of breast cancer patients with taxane CIPN measured nerve cross-sectional area (CSA) by NMUS and compared with healthy historical controls. Correlations were determined between CSA and symptom scale, nerve conduction studies, and intraepidermal nerve fiber density (IENFD). RESULTS: A total of 20 participants reported moderate CIPN symptoms at a median of 3.8 months following the last taxane dose. Sural nerve CSA was 1.2 mm2 smaller than healthy controls (P ≤ .01). Older age and time since taxane were associated with smaller sural nerve CSA. For each 1 mm2 decrease in sural nerve CSA, distal IENFD decreased by 2.1 nerve/mm (R2 0.30; P = .04). CONCLUSIONS: These data support a sensory predominant taxane neuropathy or neuronopathy and warrant future research on longitudinal NMUS assessment of CIPN.

Injury of Muscular but not Cutaneous Nerve Drives Acute Neuropathic Pain in Rats.

Acute pain is a common complication after injury of a peripheral nerve but the underlying mechanism is obscure. We established a model of acute neuropathic pain via pulling a pre-implanted suture loop to transect a peripheral nerve in awake rats. The tibial (both muscular and cutaneous), gastrocnemius-soleus (muscular only), and sural nerves (cutaneous only) were each transected. Transection of the tibial and gastrocnemius-soleus nerves, but not the sural nerve immediately evoked spontaneous pain and mechanical allodynia in the skin territories innervated by the adjacent intact nerves. Evans blue extravasation and cutaneous temperature of the intact skin territory were also significantly increased. In vivo electrophysiological recordings revealed that injury of a muscular nerve induced mechanical hypersensitivity and spontaneous activity in the nociceptive C-neurons in adjacent intact nerves. Our results indicate that injury of a muscular nerve, but not a cutaneous nerve, drives acute neuropathic pain.

Prolonged nonobstructive urinary retention induced by tibial nerve stimulation in cats.

Nonobstructive urinary retention (NOUR) is a medical condition without an effective drug treatment, but few basic science studies have focused on this condition. In α-chloralose-anesthetized cats, the bladder was cannulated via the dome and infused with saline to induce voiding that could occur without urethral outlet obstruction. A nerve cuff electrode was implanted for tibial nerve stimulation (TNS). The threshold (T) intensity for TNS to induce toe twitch was determined initially. Repeated (6 times) application of 30-min TNS (5 Hz, 0.2 ms, 4-6T) significantly (P < 0.05) increased bladder capacity to 180% of control and reduced the duration of the micturition contraction to 30% of control with a small decrease in contraction amplitude (80% of control), which resulted in urinary retention with a low-voiding efficiency of 30% and a large amount of residual volume equivalent to 130% of control bladder capacity. This NOUR condition persisted for >2 h after the end of repeated TNS. However, lower frequency TNS (1 Hz, 0.2 ms, 4T) applied during voiding partially reversed the NOUR by significantly (P < 0.05) increasing voiding efficiency to 60% and reducing residual volume to 70% of control bladder capacity without changing bladder capacity. These results revealed that tibial nerve afferent input can activate either an excitatory or an inhibitory central nervous system mechanism depending on afferent firing frequencies (1 vs. 5 Hz). This study established the first NOUR animal model that will be useful for basic science research aimed at developing new treatments for NOUR.