Middle cluneal nerve entrapment sites in the surgical field.

INTRODUCTION: Middle cluneal nerve (MCN) entrapment around the sacroiliac joint elicits low back pain (LBP). For surgical decompression to be successful, the course of the MCN must be known. We retrospectively studied the MCN course in 15 patients who had undergone MCN neurolysis. METHODS: Enrolled in this retrospective study were 15 patients (18 sides). We inspected their surgical records and videos to determine the course of the entrapped MCN. The area between the posterior superior- and the posterior inferior iliac spine was divided into areas A-D from the rostral side. The MCN transit points were identified at the midline and the lateral edge connecting the posterior superior- and posterior inferior iliac spine. Before and 6 months after surgery, the patients recorded the degree of LBP on the numerical rating scale and the Roland-Morris Disability Questionnaire. RESULTS: We decompressed 24 MCNs. The mean number was 1.3 nerves per patient (range 1-2). The MCN course was oblique in the cranio-caudal direction; the nerve tended to be observed in areas C and D. In six patients (40%), we detected two MCN branches, they were in the same area and adjacent. Postoperatively, LBP was improved significantly in all patients. CONCLUSION: Between the posterior superior- and the posterior inferior iliac spine, the MCN ran obliquely in the cranio-caudal direction; it was prominent in areas on the caudal side. In six (40%) patients, we decompressed two adjacent MCNs. Our findings are useful for MCN decompression surgery.

Cluneal nerve release: a systematic review.

BACKGROUND: Despite the heterogeneity of chronic lower back pain aetiologies, cluneal nerve entrapment remains underdiagnosed and poorly understood with few studies discussing the efficacy of its surgical release. OBJECTIVE: The current study opts to conduct a systematic review reporting on the efficacy of cluneal nerve surgical decompression in patients with an established diagnosis who fail conservative treatment. We aimed to systematically evaluate the literature regarding the clinical outcomes, recurrence of symptoms and revision rates of surgical intervention. METHODS: A systematic review of the English language literature dating up until May 2022 was undertaken according to the PRISMA guidelines. Isolated case reports were excluded. RESULTS: Of a total of 54 articles, 4 studies met the inclusion criteria (three were level IV evidence and one level III evidence) and were analyzed. Overall, 98 patients of mean age 61 years, (range 17-86) underwent cluneal nerve release with a mean follow-up of 25.5 months (6-58 months). There was significant improvement in symptoms post operatively in the 4 studies. No systemic or local complications were encountered during the surgeries. Four articles reported on revision surgery for recurrent symptoms in 8 patients out of 98 with a rate of 8.2%. Of the reoperated patients, 7/8 had new branches released that were not addressed initially and 1 had neurectomy for an adhered pre-released branch. CONCLUSION: This systematic review demonstrated that cluneal nerve decompression has been performed in a total of 98 patients with significant clinical improvement, zero systemic and local complications and revision rates of 8.2% of the cases.

Intramuscular innervation of the tensor fasciae latae: Application to total hip arthroplasty.

The aims of this study were to clarify the extra- and intramuscular branching patterns of the tensor fasciae latae (TFL) with reference to surface landmarks on the thigh and to thus suggest a safe approach for total hip arthroplasty. Sixteen fixed and four fresh cadavers were dissected and subjected to the modified Sihler's staining method to reveal the extra- and intramuscular innervation patterns, and the findings were matched with surface landmarks. The landmarks were measured from the anterior superior iliac spine (ASIS) to the patella and divided into 20 parts along the total length. The average vertical length of the TFL was 15.92 ± 1.61 cm, which was 38.79 ± 2.73% when converted to a percentage. The entry point of the superior gluteal nerve (SGN) was an average of 6.87 ± 1.26 cm (16.71 ± 2.55%) from the ASIS. In all cases, the SGN entered parts 3-5 (10.1%-25%). As the intramuscular nerve branches traveled distally, they had a tendency to innervate more deeply and inferiorly. In all cases, the main SGN branches were intramuscularly distributed in parts 4 and 5 (15.1%-25%). Most tiny SGN branches were found inferiorly in parts 6 and 7 (25.1%-35%). In three of 10 cases, very tiny SGN branches were observed in part 8 (35.1%-38.79%). We did not observe SGN branches in parts 1-3 (0%-15%). When information on the extra- and intramuscular nerve distributions was combined, we found that the nerves were concentrated in parts 3-5 (10.1%-25%). We propose that damage to the SGN can be prevented if parts 3-5 (10.1%-25%) are avoided during surgical treatment, particularly during the approach and incision.

Cluneal neuropathy: Background, diagnosis, and treatment.

BACKGROUND AND AIMS: Cluneal neuropathy is encompassed by three distinct clinical entities. Superior, middle, and inferior cluneal neuralgia make up the constellation of symptoms associated with cluneal neuropathy. Each has its own variable anatomy. MATERIALS AND METHODS: We compiled a narrative review including a review of available literature. We conducted searches on PubMed/MEDLINE, Embase and Google Scholar on the topics of cluneal neuropathy and treatment therein. RESULTS: We collected source articles regarding original descriptions of the disease entities in addition to articles focused on treatment. DISCUSSION: Adjusted incidence rates of superior cluneal neuropathy are 1.6%-11.7%. Accurate diagnosis remains challenging due to the lack of standardized criteria and the aforementioned variability. Treatment may include therapeutic nerve blocks, ablative techniques, neuromodulation, and surgical decompression. Gaps including those related to true incidence and work up exist. Outcomes from interventional studies are limited and mixed due to significant population heterogeneity and non-standardized treatment approaches coupled with very small sample sizes.

Imaging of peripheral nerve causes of chronic buttock pain and sciatica.

Chronic buttock pain is a common and debilitating symptom, which severely impacts daily activities, sleep, and may affect athletic performance. Lumbar spine, posterior hip, or hamstring pathology are usually considered as the primary diagnoses; however, pelvic neural pathology may be a significant cause of chronic buttock pain, particularly if there are prolonged (>6 months) buttock and/or radicular symptoms. The subgluteal space is the site of most pelvic causes of neural-mediated buttock pain, primarily relating to entrapment neuropathy of the sciatic nerve (deep gluteal syndrome), although other nerves within the subgluteal space including the gluteal nerves, pudendal nerve, and posterior cutaneous nerve of thigh may also be involved. Additionally, cluneal nerve entrapment at the iliac crest may result in "pseudo-sciatica". Anatomical variants of the pelvic girdle muscles and functional factors, including muscle spasm and pelvic instability, may contribute to development of deep gluteal syndrome, along with neural senescence. Imaging findings primarily relate to the presence of sciatic neuritis and peri-sciatic pathology, including neural compression and peri-neural adhesions or fibrosis. This imaging review describes the causes, magnetic resonance imaging and ultrasound imaging findings and imaging-guided treatment of pelvic neural causes of chronic buttock pain and sciatica.

High-frequency thermal coagulation to treat middle cluneal nerve entrapment neuropathy.

OBJECTIVE: Middle cluneal nerve entrapment (MCN-E) around the sacroiliac joint can elicit low back pain (LBP). Pain control can be obtained with anesthetic nerve blocks; however, when their effectiveness is transient, surgical release may be necessary. We investigated the efficacy of radiofrequency thermocoagulation (RFTC) in patients with MCN-E. METHODS: Between December 2018 and August 2019, 11 consecutive patients (4 men, 7 women; mean age 76.4 years) with intractable medial buttock pain due to MCN-E underwent MCN RFTC. The mean symptom duration was 49.5 months; pre-RFTC local MCN blocks provided pain relief for a mean of 7.7 days. The severity of pain in the medial buttock due to MCN-E was recorded before and 2, 6, 12, and 24 weeks after RFTC on the numerical rating scale (NRS) and the Roland-Morris Disability Questionnaire (RDQ). RESULTS: All patients reported pain alleviation; there were no complications. While there was a significant difference in the pre- and post-RFTC treatment NRS (p < 0.05), the RDQ scores were significantly lower only after 12 weeks. The duration of pain relief was significantly prolonged by RFTC (p < 0.05). Two patients suffered pain relapse 10 weeks post-RFTC; pain alleviation was obtained by re-RFTC performed 2 weeks after pain recurrence. Two other patients relapsed 20 and 21 weeks post-RFTC; their symptoms also disappeared by MCN block administered 24 weeks after they had undergone RFTC. CONCLUSION: RFTC may safely control intractable LBP due to MCN-E.

Clinical features of middle cluneal nerve entrapment neuropathy.

BACKGROUND: Entrapment of the middle cluneal nerve (MCN), a peripheral nerve in the buttock, can elicit low back pain (LBP). We examined the epidemiology, clinical course, and treatment of MCN entrapment (MCN-EN). METHODS: Among 383 LBP patients who visited our institute, 105 were admitted for intractable LBP. They were 42 men and 63 women; their average age was 64 years. Based on clinical symptoms, palpation, and the effects of MCN block, we suspected MCN-EN in these 105 patients, 50 of whom are our study subjects. Their treatment outcomes were assessed at the time of discharge and at follow-up visits. RESULTS: MCN-EN was diagnosed in 50 of the 383 patients (13.1%) and they were hospitalized. In 43 (11.2%), MCN-EN was associated with other diseases (superior cluneal nerve entrapment, n = 21, sacroiliac joint pain, n = 9, other, n = 13). At the time of discharge, the symptoms of patients with LBP due to MCN-EN were significantly improved by repeat MCN blocks. In 7 of the 383 patients (1.8%), LBP was improved by only MCN blocks; 5 of them had reported leg symptoms in the dorsal part of the thigh. After discharge, 22 of the 50 hospitalized patients required no additional treatments after 2-5 blocks; 19 required only conservative treatment, and 9 underwent microsurgical release of the MCN. CONCLUSIONS: We confirmed MCN-EN in 50 of 105 patients admitted for intractable LBP. Repeat MCN blocks were effective in 22 patients; 19 required additional conservative treatment, and 9 underwent surgery. Buttock pain radiating to the posterior thigh was an MCN-EN symptom that has been diagnosed as pseudo-sciatica. Before subjecting patients with intractable LBP to surgery, the presence of MCN-EN must be ruled out.

A novel method for predicting superior gluteal nerve safe zones in the lateral approach to the hip.

INTRODUCTION: The superior gluteal nerve (SGN) is at risk for laceration during lateral approach total hip arthroplasty (THA). The purpose of this study is to assess the accuracy of the trochanter-to-iliac crest distance (TCD) and the nerve-to-trochanter distance (NTD) ratio in determining a reproducible safe zone around the SGN independent of height. MATERIALS AND METHODS: Eighteen hemipelvises were dissected and the SGNs were exposed. The distance (NTD) from greater trochanter (GT) to the most inferior branch of the SGN encountered in each of the three approaches (Bauer et al., 1979) was measured. A reference distance (TCD) was measured from the GT to the highest point on the iliac crest. The NTD was divided by the TCD to generate standardized ratios. Coefficient of variation CV = (SD/mean) × 100 was calculated for each distance and ratio to measure relative variability. RESULTS: The standardized ratios (and CV) were determined for the nerve branches in three different surgical approaches: Hardinge 0.464 (0.9%), Bauer 0.406 (1.7%), and Frndak 0.338 (4.1%). There was a strong correlation of the individual NTDs with the TCD: NTD for Hardinge (r = 0.996, p < .001), NTD for Bauer (r = 0.984, p < .001), and NTD for Frndak (r = 0.932, p < .001). CONCLUSION: By measuring the TCD preoperatively and using the respective standardized ratios, surgeons can accurately predict the NTD and how proximal to the GT each SGN branch can be expected to be encountered during lateral approach to the hip. This will allow surgeons to work with a more precise safe zone around the SGN and minimize the possibility for a nerve injury.

Pain Syndromes Secondary to Cluneal Nerve Entrapment.

PURPOSE OF REVIEW: The purpose of this review is to provide an overview of the cluneal nerves, present a summary of pain syndromes secondary to clunealgia, and evaluate current literature for diagnostic and treatment modalities. RECENT FINDINGS: Multiple trials and studies have reported success with numerous modalities ranging from nerve blocks, neuroablation, and even peripheral neuromodulation with varying degrees of clinical benefit. Cluneal nerve entrapment or chronic impingement can cause buttock pain or referred pain to nearby areas including the lower back, pelvic area, or even the lower extremities. Clunealgias and associated pain syndromes can often be challenging to diagnose and differentiate. An appreciation of the pathophysiology of clunealgias can assist with patient selection for interventional pain strategies targeted towards the cluneal nerves, including nerve blocks, neuroablation, and peripheral neuromodulation. More research is needed to better delineate the efficacy of these procedures for clunealgias.

Gluteus medius muscle decompression for buttock pain: a case-series analysis.

BACKGROUND: The causes of low back and buttock pain are variable. Elsewhere, we presented a surgical technical note addressing the gluteus medius muscle (GMeM) pain that elicited buttock pain treatable by surgical decompression. Here, we report minimum 2-year surgical outcomes of GMeM decompression for intractable buttock pain. METHODS: Between January 2014 and December 2015, we surgically treated 55 consecutive patients with a GMeM pain. Of these, 39 were followed for at least 2 years; they were included in this study. Their average age was 69.2 years; 17 were men and 22 were women. The affected side was unilateral in 24 patients and bilateral in the other 15 (total 54 sites). The mean follow-up period was 40.0 months (range 25-50 months). The severity of pre- and post-treatment pain was recorded on the numerical rating scale (NRS) and the Roland-Morris Disability Questionnaire (RDQ). RESULTS: Of the 39 patients, 35 also presented with leg symptoms. They were exacerbated by walking in all 39 patients and by prolonged sitting in 33 patients; 19 had a past history of lumbar surgery and 4 manifested failed back surgery syndrome. Repeat surgery for wider decompression was performed in 5 patients due to pain recurrence 15.8 months after the first operation. At the last follow-up, the symptoms were significantly improved; the average NRS fell from 7.4 to 2.1 and the RDQ score from 10.5 to 3.3 (p < 0.05). CONCLUSIONS: When diagnostic criteria are met, GMeM decompression under local anesthesia is a useful treatment for intractable buttock pain.

Safe Gluteal Fat Graft Avoiding a Vascular or Nervous Injury: An Anatomical Study in Cadavers.

Background: Fat grafting for gluteal augmentation is one of the most popular aesthetic surgery procedures. It has an associated mortality to fat embolism of 0.2%. Objectives: The authors of this study sought to describe which technique for synthetic graft application was least likely to cause a fat embolism. Methods: Ten fresh bodies were obtained and 4 groups arranged with 5 buttocks each randomly assigned. Group 1 was infiltrated through the upper medial intergluteal sulcus (upper medial intergluteal sulcus) with an angulation of -30°, -10°, and 0°. Group 2 was infiltrated through the middle lower gluteal sulcus with an angulation of -30°, 0°, and +15°. Group 3 was infiltrated through a peritrochanteric (PT) access at the level of the femur head at 0° and +10° and in the middle of the buttock at the level of the posterior superior iliac crest at -30° toward the trochanter (lateral direction). Group 4 was infiltrated in the same manner as group 1 without -30°. A complication occurred when the graft was in contact with the vascular or nervous bundle, within the gluteus medius muscle, or both. Results: Group 1 had 3 buttocks with a complication (UMIGS -30°). Group 2 had complications in all the injection techniques. Group 3 had 5 buttocks with a complication (PT at 0°). Group 4 had no complications. Conclusions: The injection of the fat graft through the UMIGS at 0° and 10° angles, and through the middle of the buttock at the level of posterior superior iliac crest a -30° angle, reaches the surface needed for gluteal augmentation. The group 2 techniques should be avoided because they have a high risk of complication.

Ultrasound-Guided Posterior Femoral Cutaneous Nerve Block: A Cadaveric Study.

OBJECTIVES: To identify any anatomic barriers to local anesthetic spread between the sciatic nerve (SN) and the posterior femoral cutaneous nerve (PFCN) at the level of the infragluteal crease and to describe a potential technique for an ultrasound (US)-guided subgluteal PFCN block in a cadaveric model. METHODS: Bilateral US-guided subgluteal injections of a colored latex solution were performed around the SN (15 mL) and PFCN (10 mL) in 4 unembalmed cadavers, for a total of 8 cadaver thighs. The specimens were dissected after latex polymerization to observe the spread of the latex solutions. RESULTS: With US guidance, the PFCN was visualized deep to the gluteus maximus and slightly superficial or lateral to the SN at the level of the infragluteal crease. The SN and PFCN were found on dissection to be coated with their respective colored latex in all 8 thighs. The SN and PFCN were consistently separated by the deep investing muscular fascia of the thigh, with only 2 thighs showing substantial mixing of latex injectates. CONCLUSIONS: The deep investing muscular fascia of the thigh appears to impede the spread of injectate between the SN and PFCN in a most unembalmed cadaver specimens. A US-guided subgluteal PFCN blockade may be a feasible technique to complement an SN block when complete anesthesia of the posterior thigh is required.

Gemelli-obturator complex in the deep gluteal space: an anatomic and dynamic study.

OBJECTIVE: To investigate the behavior of the sciatic nerve during hip rotation at subgluteal space. MATERIALS AND METHODS: Sonographic examination (high-resolution ultrasound machine at 5.0-14 MHZ) of the gemelli-obturator internus complex following two approaches: (1) a study on cadavers and (2) a study on healthy volunteers. The cadavers were examined in pronation, pelvis-fixed position by forcing internal and external rotations of the hip with the knee in 90° flexion. Healthy volunteers were examined during passive internal and external hip rotation (prone position; lumbar and pelvic regions fixed). Subjects with a history of major trauma, surgery or pathologies affecting the examined regions were excluded. RESULTS: The analysis included eight hemipelvis from six fresh cadavers and 31 healthy volunteers. The anatomical study revealed the presence of connective tissue attaching the sciatic nerve to the structures of the gemellus-obturator system at deep subgluteal space. The amplitude of the nerve curvature during rotating position was significantly greater than during resting position. During passive internal rotation, the sciatic nerve of both cadavers and healthy volunteers transformed from a straight structure to a curved structure tethered at two points as the tendon of the obturator internus contracted downwards. Conversely, external hip rotation caused the nerve to relax. CONCLUSION: Anatomically, the sciatic nerve is closely related to the gemelli-obturator internus complex. This relationship results in a reproducible dynamic behavior of the sciatic nerve during passive hip rotation, which may contribute to explain the pathological mechanisms of the obturator internal gemellus syndrome.

Direct anterior versus anterolateral approach in one-stage supine total hip arthroplasty. Focused on nerve injury: A prospective, randomized, controlled trial.

BACKGROUND: The difference in clinical results between the direct anterior approach (DAA) and the anterolateral approach (ALA) for total hip arthroplasty (THA) is still unclear. The purpose of this study was to compare clinical results, including nerve injuries, between DAA and ALA in one-stage bilateral THA in a prospective, randomized controlled trial. METHODS: Thirty patients were recruited for primary bilateral THAs from 2014 to 2016. The left and right hips of each patient were randomly assigned to DAA and the others to ALA. We prospectively compared the clinical results, incidence of lateral femoral cutaneous nerve (LFCN) injury, and tensor fascia lata (TFL) atrophy considered to be related to superior gluteal nerve injury between both approaches. RESULTS: No significant difference was found in the clinical results between both sides at postoperative 1 year. Temporary symptom of LFCN injury was observed only in DAA sides (7/30, 23.3%). The ratio of 3-month postoperative to preoperative cross-sectional area of TFL on computed tomography was significantly lower on the side subjected to DAA (DAA side, 78.8 ± 22.8%) than on the side subjected to ALA (ALA side, 90.7 ± 17.7%) (p < 0.01). In magnetic resonance imaging at postoperative 1 year, the mean grade of fatty atrophy of TFL by Goutalier classification was significantly higher in DAA sides (2.00 ± 1.6) than in ALA sides (1.1 ± 1.3) (p = 0.03). CONCLUSIONS: Excellent clinical results for both DAA and ALA were achieved. LFCN injury was found only in DAA sides. Although TFL atrophy was found in both approaches, it was found significantly more in DAA sides. Our study suggested that ALA should be used rather than DAA in terms of the risk of nerve injuries.

The inferior gluteal nerve often has a cutaneous branch: A discovery with application to hip surgery and targeting gluteal pain syndromes.

The inferior gluteal nerve has been traditionally described as a solely motor branch innervating the gluteus maximus. However, during routine dissection of the gluteal region, a cutaneous branch of the inferior gluteal nerve was identified. As the gluteal region is vulnerable to the development of pressure ulcers and iatrogenic injury with for example, surgical approaches and injection therapies, a comprehensive understanding of its cutaneous innervation is important. Therefore, the aim of this study was to elucidate the anatomy of this cutaneous branch of the inferior gluteal nerve in a series of cadavers. Twelve sides from six fresh-frozen cadaveric specimens were dissected. When a cutaneous branch was identified piercing the gluteus maximus, its origin from the inferior gluteal nerve was verified and the diameter and length of it measured. Additionally, for localization, the distance from the midline to the exit point of the cutaneous branch from the gluteus maximus was measured. One to two cutaneous branches were identified as arising from the inferior gluteal nerve on nine sides (75%). The branch(es) were usually located in the lower outer quadrant of the gluteus maximus. These branches had a mean distance of 12.5 cm from the midline. Their mean diameter and length was 0.7 mm and 28.6 cm, respectively. On all sides with a cutaneous branch of the inferior gluteal nerve, the skin over the posterior aspect of the greater trochanter was innervated by superior and inferior cluneal nerves and supplemented by cutaneous branch(es) of the inferior gluteal nerve. Side or sex was not a predictor of the presence of a cutaneous branch of the inferior gluteal nerve. To our knowledge, a cutaneous branch derived from the inferior gluteal nerve has not been previously described. Based on our cadaveric findings, the majority of individuals will have the area of skin over the greater trochanter innervated by this nerve. Therefore, surgeons and pain specialists should be aware of its presence and might develop surgical procedures that help avoid it or develop technical advances that target it for various pain syndromes in this area. We propose naming these cutaneous branches the lateral cluneal nerves, which would necessitate renaming the middle cluneal nerves to medial cluneal nerves. Clin. Anat. 31:937-941, 2018. © 2018 Wiley Periodicals, Inc.

The distance of the gluteal nerve in relation to anatomical landmarks: an anatomic study.

INTRODUCTION: Gluteal insufficiency is of concern with lateral approaches to total hip arthroplasty. Damage to the branches of the superior gluteal nerve may cause degeneration of the innervated muscles. The direct anterior approach exploits the intermuscular and internerval interval between tensor fasciae latae laterally and sartorius and rectus femoris muscle medially. In this study, the distance of the superior gluteal nerve in relation to anatomical landmarks was determined. MATERIALS AND METHODS: Two experienced surgeons implanted trial components in 15 alcohol glycerol fixed cadavers with 30 hips. The trials were removed, and the main branch of the superior gluteal nerve and muscular branches of the nerve were exposed from lateral. RESULTS: No visual damage to the main nerve branches and the location of the nerve in relation to the greater trochanter were noted by an experienced surgeon. The superior gluteal nerve and its muscular branches crossed the muscular interval between the gluteus medius and tensor fasciae latae muscles at a mean distance of 39 mm from the tip of the greater trochanter. CONCLUSIONS: The direct anterior approach for total hip arthroplasty minimizes the risk of injuring the superior gluteal nerve, which may result in a gluteal insufficiency. Special care should be paid on avoiding overstretching the tensor fasciae latea muscle using minimum force on retractors during surgery and by taking care of the entrance point of the superior gluteal nerve to the tensor fasciae latae.

Aripiprazole Once-Monthly 400 mg: Comparison of Pharmacokinetics, Tolerability, and Safety of Deltoid Versus Gluteal Administration.

Background: Two open-label, randomized, parallel-arm studies compared pharmacokinetics, safety, and tolerability of aripiprazole once-monthly 400 mg following deltoid vs gluteal injection in patients with schizophrenia. Methods: In the single-dose study, 1 injection of aripiprazole once-monthly 400 mg in the deltoid (n=17) or gluteal (n=18) muscle (NCT01646827) was administered. In the multiple-dose study, the first aripiprazole once-monthly 400 mg injection was administered in either the deltoid (n=71) or gluteal (n=67) muscle followed by 4 once-monthly deltoid injections (NCT01909466). Results: After single-dose administration, aripiprazole exposure (area under the concentration-time curve) was similar between deltoid and gluteal administrations, whereas median time to maximum plasma concentration was shorter (7.1 [deltoid] vs 24.1 days [gluteal]) and maximum concentration was 31% higher after deltoid administration. In the multiple-dose study, median time to maximum plasma concentration for deltoid administration was shorter (3.95 vs 7.1 days), whereas aripiprazole mean trough concentrations, maximum concentration, and area under the concentration-time curve were comparable between deltoid and gluteal muscles (historical data comparison). Multiple-dose pharmacokinetic results for the major metabolite, dehydro-aripiprazole, followed a similar pattern to that of the parent drug for both deltoid and gluteal injection sites. Safety and tolerability profiles were similar after gluteal or deltoid injections. Based on observed data, minimum aripiprazole concentrations achieved by aripiprazole once-monthly 400 mg are comparable with those of oral aripiprazole 15 to 20 mg/d. Conclusions: The deltoid muscle is a safe alternative injection site for aripiprazole once-monthly 400 mg in patients with schizophrenia.

Entrapment of the posterior femoral cutaneous nerve and its inferior cluneal branches: anatomical basis of surgery for inferior cluneal neuralgia.

PURPOSE: The apparent failure of pudendal nerve surgery in some patients has led us to suggest the possibility of entrapment of other adjacent nerve structures, leading to the concept of inferior cluneal neuralgia. Via its numerous collateral branches, the posterior femoral cutaneous nerve innervates a very extensive territory including the posterior surface of the thigh, the infragluteal fold, the skin over the ischial tuberosity, but also the lateral anal region, scrotum or labium majus via its perineal branch. METHODS: We described the pathophysiological features of cluneal neuralgia, the surgical technique and our preliminary results. RESULTS: We performed a transmuscular approach leading to the fat of the deep gluteal region. Exploration was continued cranially underneath the piriformis, looking for potential entrapments affecting the posterior femoral cutaneous nerve and the sciatic nerve. Nerve decompression on the lateral surface of the ischial tuberosity was then performed. A constant anatomical finding must be highlighted: the presence of a lateral fibrous expansion from the ischium passing behind the nerves and vessels, especially the posterior femoral cutaneous nerve and its perineal branches. In our patients, release of this expansion allowed decompression of the nerve trapped by this expansion. CONCLUSION: Cluneal neuralgia constitutes a distinct entity of perineal pain, which must be identified and distinguished from pudendal neuralgia. Surgery should be performed via a transgluteal approach. A lateral ischial obstacle must be investigated, in the form of a constant fibrous expansion, which, like a retinaculum, can cause nerve entrapment.

Inferior gluteal and other nerves associated with sacrospinous ligament: a cadaver study.

BACKGROUND: Reported rates of gluteal pain after sacrospinous ligament fixation range from 12-55% in the immediate postoperative period and from 4-15% 4-6 weeks postoperatively. The source of gluteal pain often is attributed to injury to the nerve to levator ani or pudendal nerve. The inferior gluteal nerve and other sacral nerve branches have not been examined thoroughly as potential sources of gluteal pain. OBJECTIVES: The purpose of this study was to further characterize anatomy of the inferior gluteal nerve and other nerves that are associated with the sacrospinous ligament from a combined gluteal and pelvic approach and to correlate findings to sacrospinous ligament fixation. STUDY DESIGN: Dissections were performed in female cadavers that had not been embalmed with gluteal and pelvic approaches. From a pelvic perspective, the closest structure to the superior border of the sacrospinous ligament midpoint was noted, and the sacral nerves that perforated the ventral surface of coccygeus muscle were examined. From a gluteal perspective, the closest distances from ischial spine to the pudendal, inferior gluteal, posterior femoral cutaneous, and sciatic nerves were measured. In addition, the closest distance from the midpoint of sacrospinous ligament to the inferior gluteal nerve and the origin of this nerve were documented. The thickness and height of the sacrospinous ligament at its midpoint were measured. Sacral nerve branches that coursed between the sacrospinous and sacrotuberous ligaments were assessed from both a pelvic and a gluteal approach. Descriptive statistics were used for data analysis. RESULTS: Fourteen cadavers were examined. From a pelvic perspective, the closest structure to the superior border of sacrospinous ligament at its midpoint was the S3 nerve (median distance, 3 mm; range, 0-11 mm). Branches from S3 and/or S4 perforated the ventral surface of coccygeus muscles in 94% specimens. From a gluteal perspective, the closest structure to ischial spine was the pudendal nerve (median distance, 0 mm; range, 0-9 mm). Median closest distance from inferior gluteal nerve to ischial spine and to the midpoint of sacrospinous ligament was 28.5 mm (range, 6-53 mm) and 31.5 mm (range, 10-47 mm), respectively. The inferior gluteal nerve arose from dorsal surface of combined lumbosacral trunk and S1 nerves in all specimens; a contribution from S2 was noted in 46% of hemipelvises. At its midpoint, the sacrospinous ligament median thickness was 5 mm (range, 2-7 mm), and its median height was 14 mm (range, 3-22 mm). In 85% of specimens, 1 to 3 branches from S3 and/or S4 nerves pierced or coursed ventral to the sacrotuberous ligament and perforated the inferior portion of the gluteus maximus muscle. CONCLUSIONS: Damage to the inferior gluteal nerve during sacrospinous ligament fixation is an unlikely source for postoperative gluteal pain. Rather, branches from S3 and/or S4 that innervate the coccygeus muscles and those coursing between the sacrospinous and sacrotuberous ligaments to supply gluteus maximus muscles are more likely to be implicated. A thorough understanding of the complex anatomy surrounding the sacrospinous ligament, limiting depth of needle penetration into the ligament, and avoiding extension of needle exit or entry point above the upper extent of sacrospinous ligament may reduce nerve entrapment and postoperative gluteal pain.

Which level is responsible for gluteal pain in lumbar disc hernia?

BACKGROUND: There are many different reasons why patients could be experiencing pain in the gluteal area. Previous studies have shown an association between radicular low back pain (LBP) and gluteal pain (GP). Studies locating the specific level responsible for gluteal pain in lumbar disc hernias have rarely been reported. METHODS: All patients with lumbar disc herniation (LDH) in the Kanghua hospital from 2010 to 2014 were recruited. All patients underwent a lumbar spine MRI to clarify their LDH diagnosis, and patients were allocated to a GP group and a non-GP group. To determine the cause and effect relationship between LDH and GP, all of the patients were subjected to percutaneous endoscopic lumbar discectomy (PELD). RESULTS: A total of 286 cases were included according to the inclusive criteria, with 168 cases in the GP group and 118 cases in the non-GP group. Of these, in the GP group, 159 cases involved the L4/5 level and 9 cases involved the L5/S1 level, while in the non-GP group, 43 cases involved the L4/5 level and 48 cases involved the L5/S1 level. PELD was performed in both groups. Gluteal pain gradually disappeared after surgery in all of the patients. Gluteal pain recrudesced in a patient with recurrent disc herniation (L4/5). CONCLUSIONS: As a clinical finding, gluteal pain is related to low lumbar disc hernia. The L4/5 level is the main level responsible for gluteal pain in lumbar disc hernia. No patients with gluteal pain exhibited involvement at the L3/4 level.