Endometriosis con infiltración aislada del nervio ciático, una forma de presentación atípica: reporte de un caso clínico / Isolated infiltrative endometriosis of the sciatic nerve, an atypical presentation: clinical case report

INTRODUCCIÓN: La endometriosis afecta hasta un 10-15% de las mujeres jóvenes. Se define como tejido endometrial funcional fuera de la cavidad uterina y su presentación clásica es la dismenorrea. La variedad profunda afecta a un 1-2% y las localizaciones más frecuentes son el peritoneo pélvico, ovarios, ligamentos útero-sacros y septum recto-vaginal; sin embargo, puede presentarse de forma muy infrecuente como implantes aislados localizados en relación al nervio ciático. El diagnóstico habitualmente es complejo y tardío, dado que los síntomas son inespecíficos y el examen físico puede ser indistinguible de otras etiologías. El estudio imagenológico de elección para la endometriosis profunda es la resonancia magnética (RM) de pelvis ya que una adecuada localización pre-quirúrgica de las lesiones es fundamental. CASO CLÍNICO: Paciente de sexo femenino de 46 años, con tres años de dolor pélvico, dismenorrea y dispareunia. El síntoma cardinal fue dolor ciático progresivo, con déficit motor y alteraciones sensitivas, los cuales se exacerbaban durante la menstruación y no presentaban respuesta al tratamiento farmacológico. En la RM se identifica nódulo sólido sospechoso de endometriosis en relación al nervio ciático derecho. El caso es evaluado por un comité multidisciplinario y se realiza cirugía laparoscópica. El diagnóstico de sospecha es confirmado histológicamente. La paciente presenta buena recuperación post-quirúrgica y cese completo de los síntomas descritos. DISCUSIÓN: La endometriosis profunda presenta un reto diagnóstico y habitualmente es tardío. Este caso presenta el resultado exitoso de una buena sospecha clínica, un estudio imagenológico completo y la resolución con una técnica quirúrgica compleja.

INTRODUCTION: Endometriosis is a disease that affects 10-15% of young women. It is characterized as functional endometrial tissue outside the uterine cavity. The most common form of presentation is dysmenorrhea. Deep endometriosis affects 1-2% of the patients, and is frequently located in the pelvic peritoneum, ovaries, utero-sacral ligaments and recto-vaginal septum. The isolated endometriosis of the sciatic nerve is a very uncommon presentation of this disease. Late diagnosis is frequent, mainly because the symptoms are non-specific, and the physical examination may be indistinguishable from other etiologies. The imaging study of choice is the pelvic magnetic resonance imaging (MRI) and an accurate pre-surgical location of the lesions is critical for a successful surgical outcome. CLINICAL CASE: 46-year-old female patient with 3 years of pelvic pain, dysmenorrhea and dyspareunia. The cardinal symptom was progressive sciatic pain, with motor deficit and sensory alterations. The pain was persistent despite pharmacological treatment and exacerbated during menstruation. MRI identifies a nodule located in the pelvic portion of the right sciatic nerve, suggestive of an endometriosis implant. The case was discussed by a multidisciplinary committee and laparoscopic surgery was performed. The diagnosis was confirmed with histology. The patient recovered well from surgery with significant improvement of the previously described symptoms. DISCUSSION: The diagnosis of deep endometriosis is challenging and usually delayed. This rare disease had a successful outcome, due to an early clinical suspicion, a thorough imaging study and an effective resolution with a complex surgical technique.

Influencia de la posición en la visualización con ultrasonido del nervio ciático en la fosa poplítea por médicos en formación / Patient positioning and ultrasound visualization of the sciatic nerve in the fossa by anesthesia residents

OBJECTIVE: Evaluate the effect of the patients' position in obtaining a good quality image of the sciatic nerve at the popliteal fossa by anesthesiology trainees. METHODS: First and 2nd year residents of our anesthesiology program scanned de right popliteal fossa of a unique subject. The subject laid in 3 different positions (supine, lateral and prone). Before the scanning, residents reviewed a video showing basic ultrasound probe management and images of the sciatic nerve at the popliteal fossa. Time elapsed upon receiving the ultrasound probe and obtaining a good quality image was measured (at least 70% counter definition and 3 clearly identified structures within the nerve). An evaluator (blinded to the subject position) determined during real time observation the quality of the image. Residents completed a questionnaire regarding the experience lived. RESULTS AND CONCLUSIONS: 26 residents completed the study. There were no statistical differences in the overall time needed by residents to obtain a good quality image in the 3 different positions. Although 96% felt that position influenced the ability to obtain good image. From this experience residents would prefer to do an US guided popliteal block on the prone position.

OBJETIVOS: Evaluar la influencia de la posición del paciente en la obtención de una imagen de calidad del nervio ciático a nivel poplíteo por médicos en formación del programa de anestesiología. METODOLOGÍA: Médicos en formación del programa de Anestesiología examinarán desde la cara posterior la fosa poplítea derecha de un único sujeto en tres posiciones diferentes. Previamente serán expuestos a un video del uso del ecógrafo y de imágenes del nervio ciático a nivel poplíteo. Se consignará el tiempo desde que reciben el transductor hasta obtener imagen del nervio ciático con al menos 70% de definición de contorno y más de 3 estructuras visibles en su interior. Un investigador en tiempo real, ciego a la posición del modelo, decidirá si la imagen cumple los criterios. Finalmente completan una encuesta sobre apreciación subjetiva de la experiencia. RESULTADOS Y CONCLUSIONES: Se evaluaron 26 residentes en total. No hubo deferencias en el tiempo que necesitaron para obtener una imagen de buena calidad del nervio ciático a nivel de la fosa poplítea en las distintas posiciones.

Sciatic Nerve Variants in Patients Diagnosed With Sciatica: Is There a Correlation?

PURPOSE: Compression of the sciatic nerve in its path along the piriformis muscle can produce sciatica-like symptoms. There are 6 predominant types of sciatic nerve variations with type 1 being the most common (84.2%), followed by type 2 (13.9%). However, there is scarce literature on the prevalence of sciatic nerve variation in those diagnosed with sciatica. MATERIALS AND METHODS: The charts of 95 patients clinically diagnosed with sciatica who had a magnetic resonance imaging of the pelvis/hip were retrospectively studied. All patients had T1-weighted axial, coronal, and sagittal images. Magnetic resonance imagings were interpreted separately by 2 board-certified fellowship-trained musculoskeletal radiologists to identify the sciatic nerve variant. RESULTS: Seven cases were excluded because of inadequate imaging. Of the remaining 88 patients, 5 had bilateral sciatica resulting in a sample size of 93 limbs. Fifty-two (55.9%) had type 1 sciatic nerve anatomy, 39 (41.9%) had type 2, and 2 (2.2%) had type 3. The proportions of type 1 and 2 variations were significantly different from the normal distribution (P < 0.001), whereas type 3, 4, 5, and 6 variants were not (P = 1.00). CONCLUSIONS: There is strong statistical significance regarding the relationship between sciatic nerve variation and the clinical diagnosis of sciatica. Preoperative magnetic resonance imaging can be considered in sciatica patients to prevent iatrogenic injury in pelvic surgery.

A Randomized Comparison Between Single- and Triple-Injection Subparaneural Popliteal Sciatic Nerve Block.

BACKGROUND AND OBJECTIVES: This prospective randomized trial compared ultrasound-guided single-injection (SI) and triple-injection (TI) subparaneural popliteal sciatic nerve block. We hypothesized that multiple injections are not required when local anesthetic (LA) is deposited under the paraneurium because the latter entraps LA molecules, ensuring circumferential spread around the nerve. Therefore, in addition to comparable success rates, we also expected similar total anesthesia-related times (sum of performance and onset times) and designed this study as an equivalency trial. METHODS: Ultrasound-guided subparaneural posterior popliteal sciatic nerve block was carried out in 100 patients. In the SI group, LA was deposited at a single location between the tibial and peroneal nerves. In the TI group, LA was injected between the tibial and peroneal divisions, medial to the tibial nerve, and lateral to the common peroneal nerve. The total LA volume (15 mL) and mixture (lidocaine 1%-bupivacaine 0.25%-epinephrine 5 µg/mL) were identical in all subjects. The performance time, number of needle passes, and adverse events (paresthesia, neural edema) were recorded by the (nonblinded) investigator supervising the block. A blinded observer evaluated the success rate (sensorimotor composite score ≥6/8 points at 30 minutes) as well as the onset time and contacted patients 7 days after the surgery to inquire about persistent numbness or motor deficit. RESULTS: Both techniques provided comparable success rates (92%) and total anesthesia-related times (17.1-19.7 minutes). Expectedly, the SI group required fewer needle passes (1 vs 3; P < 0.001) and a shorter needling time (3.0 ± 2.3 minutes vs 4.0 ± 2.3 minutes; P = 0.025). The TI group displayed a shorter onset time (12.5 ± 7.9 minutes vs 15.8 ± 7.9 minutes; P = 0.027). The performance time, procedural discomfort, and incidence of paresthesia (14%-20%) were similar between the 2 groups. Sonographic neural swelling was detected in 2 subjects in the SI group. In both cases, the needle was carefully withdrawn and the injection was completed uneventfully. Follow-up of the 100 subjects 1 week after surgery revealed no residual numbness or motor deficit. CONCLUSIONS: Ultrasound-guided SI and TI subparaneural popliteal sciatic nerve blocks result in comparable success rates and total anesthesia-related times. Expectedly, the SI technique requires fewer needle passes.

Are human peripheral nerves sensitive to X-ray imaging?

Diagnostic imaging techniques play an important role in assessing the exact location, cause, and extent of a nerve lesion, thus allowing clinicians to diagnose and manage more effectively a variety of pathological conditions, such as entrapment syndromes, traumatic injuries, and space-occupying lesions. Ultrasound and nuclear magnetic resonance imaging are becoming useful methods for this purpose, but they still lack spatial resolution. In this regard, recent phase contrast x-ray imaging experiments of peripheral nerve allowed the visualization of each nerve fiber surrounded by its myelin sheath as clearly as optical microscopy. In the present study, we attempted to produce high-resolution x-ray phase contrast images of a human sciatic nerve by using synchrotron radiation propagation-based imaging. The images showed high contrast and high spatial resolution, allowing clear identification of each fascicle structure and surrounding connective tissue. The outstanding result is the detection of such structures by phase contrast x-ray tomography of a thick human sciatic nerve section. This may further enable the identification of diverse pathological patterns, such as Wallerian degeneration, hypertrophic neuropathy, inflammatory infiltration, leprosy neuropathy and amyloid deposits. To the best of our knowledge, this is the first successful phase contrast x-ray imaging experiment of a human peripheral nerve sample. Our long-term goal is to develop peripheral nerve imaging methods that could supersede biopsy procedures.

Ultrasound-guided femoral and sciatic nerve blocks in an anticoagulated patient. Case reports.

BACKGROUND AND OBJECTIVES: The use of the ultrasound to guide the puncture in peripheral nerve blocks has become increasingly more frequent. With the lower probability of promoting vascular damage the ultrasound has become an interesting tool in peripheral nerve blocks especially in patients in use of anticoagulants or with coagulopathies. The objective of this article was to report two cases in which ultrasound-guided sciatic and femoral nerve blocks were performed in anticoagulated patients. CASE REPORTS: In the first case, the patient underwent amputation of the left forefoot due to necrosis and signs of infection, and in the second case, surgical cleaning of the left knee. Patients had changes in coagulation with levels of activity of prothrombin and activated partial thromboplastin time above normal limits. Both patients underwent ultrasound-guided femoral and sciatic nerve blocks, evolving without motor or sensorial changes in the territories of those nerves and without hematoma at the site of puncture. CONCLUSIONS: Anticoagulation imposes some restrictions to classical regional anesthetic techniques. With the development of ultrasound equipment and methods, it is now possible to accurately identify vascular and neural structures. This allows ultrasound-guided puncture to be more precise, both to achieve the area of interest and to minimize the risks of accidental vascular damage. Until now, peripheral block was not recommended in anticoagulated patients or in those with coagulopathies. However, considering that few reports on ultrasound-guided regional blocks in coagulopathies can be found in the literature, the safety of this technique in this condition has yet to be established.

Ultrasound imaging of regenerating rat sciatic nerves in situ.

Following clinical or veterinary peripheral nerve trauma, it is critical to localize the site of nerve injury, determine its type, whether a crush, maceration or transection, which will indicate whether and where surgical intervention is required, and subsequently to follow the process of axon regeneration. Typical surface ultrasound probes provide resolution of more than 1mm, sufficient detail for clinically relevant data from tissue in situ, such as heart valves, organs and fetal development. Higher resolution ultrasound nerve imaging yields data to the fascicular level and allows the following of the anatomical course of a nerve, but does not allow imaging of single axons or even groups of axons, which is required to study the process of axon regeneration, neurological recovery and other important clinical and basic science questions. More significant data could be acquired with even higher frequency, and therefore higher resolution, ultrasound imaging. The present study, using a rat sciatic nerve lesion model, was performed to determine whether a new ultrasound imaging device with 30 microm resolution would allow imaging of nerve anatomy and regenerating axons, and whether the data collected from a nerve in situ was the same as when the nerve was surgically exposed. Although the increased ultrasound resolution provided good anatomical detail on the location and type of nerve damage was nearly identical for nerves in situ and when exposed, the resolution was insufficient for imaging regenerating axons. Thus, an even higher resolution ultrasound device is required to allow non-invasive imaging of axons in situ.

Ultrasound-guided block of the sciatic and femoral nerves in dogs: a descriptive study.

Ten canine cadavers were used to investigate the anatomy and ultrasonographic approaches to the sciatic (ScN) and femoral (FN) nerves and to assess the accuracy of an ultrasound (US) guided technique to locate and block these nerves in the dog. The nerves of four sedated dogs were sought using US, blocked with 1% lidocaine and successful location confirmed by peripheral neurostimulation. The ScN was identified by US in all cases whereas the FN was not located in all cases. This study validates the usefulness of the US-guided technique to locate and block the ScN at the midfemoral level but the acoustic window of the inguinal region was less successful for locating and blocking the FN.

Ultrasound-guided obturator nerve block: a preliminary report of a case series.

BACKGROUND AND OBJECTIVES: Obturator-nerve block improves analgesia for knee surgery. Traditional techniques rely on surface landmarks, which can be variable and result in excessive performance times and multiple needle passes. The objective of this study was to evaluate a novel ultrasound-guided technique for localizing the obturator nerve. METHODS: A total of 22 patients undergoing anterior cruciate ligament repair had ultrasound-guided obturator-nerve blocks. Needles were directed under real-time ultrasound guidance. Endpoint for injection consisted of identifying contact of the tip of an insulated needle to nerve confirmed by adductor muscles' contraction. Local anesthetic was injected, and block was evaluated within 30 minutes. After that, ultrasound-guided sciatic-femoral blocks were placed for surgical purposes. Data collected included: time required for nerve identification, minimum stimulating current, number of attempts for correct identification, preblock and postblock adductor muscles' strength, sensory-nerve block, and quality of surgical anesthesia. RESULTS: In 91% of cases, the obturator nerve was correctly identified on first attempt within 30 +/- 23 seconds, as a hyperechoic flat or lip-shaped structure with internal hypoechoic dots. Minimal intensity of current to nerve stimulation was 0.30 +/- 0.08 mA. All patients exhibited decreases in adductor strength. Sensory territories were variable, with no cutaneous distribution in 32% of the patients. Small-dose opioid supplementation was required in 14% of the patients, but none required general anesthesia to complete surgery. CONCLUSIONS: These preliminary data suggest that ultrasound-guided obturator-nerve identification and block are technically easy and highly successful.