Endoscopic Cubital Tunnel Release in Leprosy Neuritis of the Ulnar Nerve / Liberação endoscópica do túnel cubital na neurite hansênica do nervo ulnar

Abstract Objectives To better characterize the role of endoscopic cubital tunnel release in leprosy neuritis and determine whether there is an improvement in pain, sensitivity, and strength with the use of this minimally invasive technique. Methods A total of 44 endoscopic procedures for ulnar nerve decompression at the elbow were performed in patients who were previously diagnosed with leprosy neuritis. The inclusion criteria were surgical indication for ulnar nerve release and clinical treatment failure for 4 weeks in patients with cubital tunnel syndrome who had their ulnar nerve function, whether motor or sensitive, deteriorated progressively despite the treatment with prednisone 1 mg/kg/day and physiotherapy. For endoscopic release, the CTS Relief Kit (Linvatec. Largo, FL, USA) and a standard 4mm 30° arthroscope were used. Results The study included 39 patients, 29 (74.4%) males and 10 (25.6%) females. The age of the patients ranged from 12 to 64 years (33 ± 14.97). Five patients underwent bilateral release. The release demonstrated a statistically significant improvement in pain (p 0.002), in sensitivity (p< 0.001), and in strength (p< 0.001). The best results were obtained when ulnar release was performed less than 6 months after surgery indication. None of the procedures were converted from endoscopic to open. No major complications (infection, vascular injury, and nervous injury) were reported. One patient had ulnar nerve subluxation. Conclusion The endoscopic release of the ulnar nerve at the elbow in leprosy neuritis entails true and safe benefits for the patient, such as improvement in pain, sensitivity and strength.

Resumo Objetivos Os objetivos deste estudo foram caracterizar melhor o papel da liberação endoscópica do túnel cubital na neurite hansênica e determinar se há melhora da dor, sensibilidade e força com esta técnica minimamente invasiva. Métodos Um total de 44 procedimentos endoscópicos para descompressão do nervo ulnar no cotovelo foram realizados em pacientes previamente diagnosticados com neurite por hanseníase. Os critérios de inclusão foram indicação cirúrgica para liberação do nervo ulnar e insucesso do tratamento clínico por 4 semanas em pacientes com síndrome do túnel cubital que sofreram deterioração progressiva da função motora ou sensitiva do nervo ulnar apesar do tratamento de 1 mg/kg/dia de prednisona e fisioterapia. A liberação endoscópica foi realizada com CTS Relief Kit (Linvatec. Largo, FL, EUA) e um artroscópio padrão de 4 mm e 30°. Resultados O estudo incluiu 39 pacientes, sendo 29 (74,4%) homens e 10 (25,6%) mulheres. A idade dos pacientes variou de 12 a 64 anos (33 ± 14,97). Cinco pacientes foram submetidos à liberação bilateral. A liberação provocou melhora estatisticamente significativa de dor (p= 0,002), sensibilidade (p <0,001) e força (p <0,001). Os melhores resultados foram obtidos quando a liberação ulnar foi realizada em menos de 6 meses após a indicação da cirurgia. Nenhum procedimento foi convertido de endoscópico para aberto. Não foram relatadas complicações maiores (infecção, lesão vascular e lesão nervosa). Um paciente apresentou subluxação do nervo ulnar. Conclusão A liberação endoscópica do nervo ulnar no cotovelo na neurite hansênica traz benefícios verdadeiros e seguros para o paciente, como melhora da dor, sensibilidade e força.

Determining the utility of minimum F-wave latency alterations in the electrodiagnosis of ulnar neuropathy at the elbow / Determinação da utilidade das alterações mínimas da latência da onda F no eletrodiagnóstico da neuropatia ulnar do cotovelo

ABSTRACT Background: Ulnar neuropathy at the elbow (UNE) is the second most common entrapment neuropathy. There is little information about the application of F-wave studies for evaluation of UNE. Objective: The aim of this study was to evaluate the diagnostic value of minimum F-wave (F-min) latency alterations by comparing this with nerve conduction analyses in UNE-suspected patients. Methods: Ninety-four UNE-suspected patients were admitted to this study. Sensory and motor nerve conduction and F-wave analyses on the median and ulnar nerves were performed on both upper extremities. Results: A total of 188 upper extremities of 94 patients were examined. Their mean age was 41.4±12.9 years, and 69 patients were female (73.4%). The mean ulnar-nerve across-elbow motor conduction velocity (MCV) in the affected arms was significantly slower than the velocity in healthy arms. The mean ulnar-nerve F-min latencies were significantly longer in the affected arms. Fifty-one patients were electrophysiologically diagnosed as presenting UNE (54.2%). Significantly slower mean ulnar-nerve across-elbow MCV, longer mean ulnar-nerve F-min latency and longer distal onset latency were detected in UNE-positive arms. Lastly, patients who were symptomatic but had normal nerve conduction were evaluated separately. Only the mean ulnar F-min latency was significantly longer in this group, compared with the healthy arms. Conclusion: Our study confirmed the utility of F-min latency measurements in the electrodiagnosis of UNE. F-wave latency differences can help in making an early diagnosis to provide better treatment options.

RESUMO Introdução: A neuropatia ulnar do cotovelo (NUC) é a segunda neuropatia por encarceramento mais comum. Existem poucas informações sobre a aplicação dos estudos da onda F para avaliação da NUC. Objetivo: O objetivo deste estudo foi avaliar o valor diagnóstico das alterações mínimas de latência da onda F (F-min), comparando-as com análises de condução nervosa em pacientes com suspeita de NUC. Métodos: Noventa e quatro pacientes com suspeita de NUC foram admitidos neste estudo. A condução nervosa sensitiva e motora e as análises da onda F nos nervos mediano e ulnar foram realizadas em ambas as extremidades superiores. Resultados: Um total de 188 membros superiores de 94 pacientes foi examinado. A média de idade foi 41,4±12,9 anos e 69 pacientes eram do sexo feminino (73,4%). A velocidade de condução motora média do nervo ulnar através do cotovelo (VCM) nos braços afetados foi significativamente mais lenta do que a velocidade em braços saudáveis. As latências médias F-min do nervo ulnar foram significativamente mais longas nos braços afetados. Cinquenta e um pacientes foram diagnosticados eletrofisiologicamente como apresentando NUC (54,2%). Pacientes com presença de NUC tiveram, de forma significativa, detecção de VCM mais lenta no nervo ulnar ao nível do cotovelo, presença de latência mais longa da onda F-mínima no nervo ulnar, bem como latência de início distal mais longa. Por fim, os pacientes sintomáticos, e com condução nervosa normal, foram avaliados separadamente. Apenas a latência da onda F mínima média do nervo ulnar foi significativamente maior neste grupo, em comparação com os braços saudáveis. Conclusão: Nosso estudo confirmou a utilidade das medidas de latência da onda F-mínima no eletrodiagnóstico da NUC. As diferenças de latência da onda F podem ajudar a fazer um diagnóstico precoce para fornecer melhores opções de tratamento.

Ulnar Neuropathy at the Upper Arm after Parallel-Bars Swinging Exercise

No abstract available.

Tardy Ulnar Nerve Palsy by Neurofibroma

Tardy ulnar nerve palsy is ulnar neuropathy at or around elbow and commonly evaluated in the electromyography laboratory. However, ulnar neuropathy at the elbow due to neurofibroma is rare. Neurofibromas are tumors that arise within nerve fasciculi and anywhere along a nerve from dorsal root ganglion to the terminal nerve branch. We report one case of ulnar neuropathy at the elbow due to neurofibroma. Patient had paresthesia on the left 5th finger and there had been left hypothenar atrophy since 2 months ago. Tinel's sign was positive at left elbow. As a result of electromyography, there were suggestive of right ulnar neuropathy at or around elbow, referred to as tardy ulnar nerve palsy. Ultrasonography showed a diffuse tortuous thickening with multiple neurofibromas arising from individual fascicles of the ulnar nerve in cubital tunnel area. Surgery was then performed to release cubital tunnel of left elbow, then the patient's symptoms improved.

Diagnostic Usefulness of Neuromuscular Ultrasound in Anatomical Localization of Peripheral Nerve Injury: Detailed Lesion Localization Using Neuromuscular Ultrasound in a Patient with Traumatic Ulnar Nerve Injury at the Hand

In the evaluation of peripheral nerve injury, nerve conduction studies and needle electromyography mainly focus on anatomical localization and functional evaluation of lesions. Whereas neuromuscular ultrasound has an advantage in structural assessment of lesions. In addition, muscle ultrasound can also be used to demonstrate muscle denervation without causing pain. We report a case of traumatic ulnar nerve injury at hand in which muscle ultrasound contributed to precise localization by provided detailed information about the extent of muscle denervation.

Diagnosis of Pure Ulnar Sensory Neuropathy Around the Hypothenar Area Using Orthodromic Inching Sensory Nerve Conduction Study: A Case Report

Ulnar neuropathy at the wrist is an uncommon disease and pure ulnar sensory neuropathy at the wrist is even rarer. It is difficult to diagnose pure ulnar sensory neuropathy at the wrist by conventional methods. We report a case of pure ulnar sensory neuropathy at the hypothenar area. The lesion was localized between 3 cm and 5 cm distal to pisiform using orthodromic inching test of ulnar sensory nerve to stimulate at three points around the hypothenar area. Ultrasonographic examination confirmed compression of superficial sensory branch of the ulnar nerve. Further, surgical exploration reconfirmed compression of the ulnar nerve. This case report demonstrates the utility of orthodromic ulnar sensory inching test.

Anconeus Epitrochlearis Muscle as a Cause of Ulnar Nerve Compression at the Elbow

Ulnar nerve entrapment is the second most common compressive neuropathy in the upper limb, after carpal tunnel syndrome (Dellon, 1986). One of the causes that must be considered is the accessory anconeus epitrochlearis muscle, which is present in 4% to 34% of the general population (Husarik et al, 2010; Vanderpool et al, 1968; Nellans et al, 2014). We describe a patient with symptoms of compression of the left ulnar nerve at the elbow and the result of the surgical treatment. The patient presented with hypoesthesia in the fourth and fifth fingers of the left hand, and reduction of strength in the fifth finger abduction. No alterations were found in the thumb adduction. Initially, the treatment was conservative (splint, physiotherapy, analgesics); surgical treatment was indicated due to the continuity of the symptoms. The ulnar nerve was surgically released and transposed, with complete recovery after 6 months of follow-up. Ulnar nerve entrapment at the elbow by the anconeus epitrochlearis muscle is not common, but it must not be ignored (Chalmers, 1978). Ultrasonography (Jung et al, 2013; Bargalló et al, 2010), elbow magnetic resonance imaging (MRI) (Jeon, 2005), and electromyography (Byun, 2011) can help establish the proper diagnosis.

A compressão do nervo ulnar é a segunda causa mais frequente de neuropatia compressiva no membro superior, após a síndrome do túnel do carpo (Dellon, 1986). Uma das causas que dever ser considerada é a presença do músculo anconeu epitroclear, que está presente em cerca de 4% a 34% da população (Husarik et al, 2010; Vanderpool et al, 1968; Nellans et al, 2014). Descrevemos uma paciente com sintomas de compressão do nervo ulnar esquerdo no cotovelo, e o resultado do tratamento cirúrgico. A paciente apresentava hipoestesia no IV e V dedos da mão esquerda, e diminuição de força na abdução do V dedo; não foram encontradas alterações na adução do polegar. Inicialmente, o tratamento foi conservador (uso de splint, fisioterapia e analgésicos); a cirurgia foi indicada pela persistência dos sintomas. O nervo ulnar foi cirurgicamente liberado e transposto, com melhora total dos sintomas após 6 meses de acompanhamento. A compressão do nervo ulnar no cotovelo não é comum, mas não deve ser ignorada (Chalmers, 1978). Ultrassonografia (Jung et al, 2013; Bargalló et al, 2010), ressonância magnética do cotovelo (Jeon, 2005) e eletromiografia (Byun, 2011) auxiliam no diagnóstico.

Upper limb nerve injuries caused by intramuscular injection or routine venipuncture

The reported cases of upper limb nerve injury followed by needle procedure such as intramuscular injection or routine venipuncture are rare. However, it should not be overlooked, because neurological injury may cause not only minor transient pain but also severe sensory disturbance, hand deformity and motor dysfunction with poor recovery. Recognizing competent level of anatomy and adept skill of needle placement are crucial in order to prevent this complication. If a patient notices any experience of abnormal pain or paresthesia during the needle procedures, an administrator should be alert to the possibility of nerve injury and should withdraw the needle immediately. Careful monitoring of the injection site for hours is required for early detection of nerve injury.

Isolated Dorsal Ulnar Cutaneous Nerve Injury Occurring During Activities of Daily Living

The dorsal ulnar cutaneous nerve (DUCN) is the sensory branch of ulnar nerve supplying sensation to the dorsal ulnar aspect of the hand. Isolated DUCN injury is known rare. We report 3 cases of isolated DUCN injury caused by stretch injury and mild blunt injury during activities of daily living. Isolated DUCN injury may more frequently occur than we thought. Nerve conduction study and ultrasonography are useful method to localize the lesion and to evaluate the structural etiology.

Severe Ulnar Nerve Injury After Bee Venom Acupuncture at a Traditional Korean Medicine Clinic: A Case Report

This case report describes a severe nerve injury to the right ulnar nerve, caused by bee venom acupuncture. A 52-year-old right-handed man received bee venom acupuncture on the medial side of his right elbow and forearm, at a Traditional Korean Medicine (TKM) clinic. Immediately after acupuncture, the patient experienced pain and swelling on the right elbow. There was further development of weakness of the right little finger, and sensory changes on the ulnar dermatome of the right hand. The patient visited our clinic 7 days after acupuncture. Electrodiagnostic studies 2 weeks after the acupuncture showed ulnar nerve damage. The patient underwent steroid pulse and rehabilitation treatments. However, his condition did not improve completely, even 4 months after acupuncture.

The Effectiveness of Arthroscopic Debridement with Mini-Open Ulnar Nerve Decompression in Primary Osteoarthritis of the Elbow with Ulnar Neuropathy / 대한정형외과학회잡지

PURPOSE: The aim of this study was to determine the effectiveness of arthroscopic debridement with mini-open ulnar nerve decompression in primary osteoarthritis of the elbow with ulnar neuropathy. MATERIALS AND METHODS: Between May of 2006 and July of 2014, a total of 43 patients who had undergone surgery for primary osteoarthritis of the elbow with ulnar neuropathy were included in this study. We divided the subjects into two groups according to the method of surgery: group 1 (n=18) received mini-open ulnar nerve decompression only, and group 2 (n=25) received arthroscopic debridement with mini-open ulnar nerve decompression. Patients were assessed for the following clinical outcomes: visual analogue scales (VAS) score, range of motion of the elbow joint, Mayo elbow performance score (MEPS), and disabilities of the arm, shoulder and hand (DASH) at the time before surgery and 6 months after surgery. We analyzed the recovery of the ulnar nerve by the McGowan grade and Bishop rating score preoperatively and at 6 months after the surgery. RESULTS: The VAS score, range of motion of the elbow joint, MEPS, and DASH showed significant statistical difference after the surgery (p <0.05). However, between the 2 groups, there was no significant difference. For the McGowan grade, all cases of both groups–except one case each group–showed at least one grade improvement. Moreover, group 2 showed a greater significant difference than group 1 (p=0.001). At the final follow-up, according to the Bishop rating score, group 2 had a greater significant difference than group 1 (p=0.036). CONCLUSION: Arthroscopic debridement with mini-open ulnar nerve decompression in primary osteoarthritis of the elbow with ulnar neuropathy is a useful technique, which has several advantages, including the benefits associated with a minimally invasive surgery and also the improvement of elbow joint function and excellent recovery of the ulnar nerve.

A Neglected Markedly Displaced Medial Epicondyle Fracture with Simultaneous Ulnar Nerve Palsy in an Adolescent

Humeral medial epicondyle fractures constitute around 15% of pediatric elbow fractures. Up to 60% occur in association with elbow dislocations. Knowledge of potential imaging pitfalls when examining acute elbow fractures in children contributes significantly to accurate diagnosis. Nevertheless, management of missed pediatric medial epicondyle fractures has rarely been reported. We present an 11-year-old boy with a neglected and severely displaced medial epicondyle fracture with concurrent ulnar nerve palsy. We performed neural decompression, fragment excision, and muscular and capsuloligamentous reconstruction of the medial elbow. This study demonstrates that the surgical outcome of a late presenting fracture can be satisfactory in terms of function and neural recovery. It also underscores the importance of careful interpretation of elbow imaging including normal anatomic variants.

Ulnar neuropathy

Cubital tunnel syndrome is the second most common compressive neuropathy. Its diagnosis is largely based on clinical findings. It has been well known that patients with mild to moderate grade of cubital tunnel syndrome have a high chance of spontaneous resolution, while those with severe degree do not. Thus, the former is treated with conservative methods initially, and the latter is indicated for surgical intervention. There are three types of surgical techniques for cubital tunnel syndrome. Of these, in-situ decompression technique has been gaining popularity as it is simpler and shows similar efficacy with less complications compared to other techniques. In this review, we deal with current concepts of the cubital tunnel syndrome pertaining to the primary clinical practice.

Surgical Treatment of the Primary Osteoarthritis of the Elbow: Open vs. Arthroscopy

The characteristic of primary osteoarthritis of the elbow is marginal osteophyte and loose body formation with relatively preserving cartilage, manifesting as a painful and limited motion arc. In moderate degenerative changes, a debridement that remove the bony impingement as a basis of the surgical treatment can be performed by arthroscopic as well as open procedure. This article tries to suggest the indication of arthroscopic or open procedure by comparative analyzing the advantages and disadvantages of each method. As a result, arthroscopic procedure may be recommended when the range of motion is greater than 100° and main symptom is pain, on the other hand open debridement may be recommended when the range of motion is less than 100°, main symptom is limited motion, especially further flexion and ulnar neuropathy is accompanied.

Ultrasound Evaluation of Ulnar Neuropathy at the Elbow Caused by a Mass Lesion / 대한임상신경생리학회지

Ulnar neuropathy at the elbow (UNE) may seem easy to diagnose when the characteristic clinical manifestations are present, and electrodiagnostic studies have high sensitivity, although they are non-localizing in some cases and unable to reveal structural lesions. Ultrasonography is noninvasive and able to find the exact location of the lesion and visualize perineural structures. We present two cases of UNE in which we found hypoechoic mass lesions near medial epicondyle with ultrasonography and discuss its usefulness in diagnosis of UNE.

Comparison of Cubital Tunnel Syndrome with or without Anconeus Epitrochlearis: Are They Different?

PURPOSE: To assess the clinical difference between cubital tunnel syndrome with anconeus epitrochlearis (AE) and idiopathic cubital tunnel syndrome without known other causes. METHODS: This cross-sectional study included the 326 patients who were subjected to surgery because of cubital tunnel syndrome from 2008 to 2014. After exclusion of patients with other known causes of cubital tunnel syndrome, a total of 107 patients were divided into two groups; patients with and without AE. The clinical differences between two groups were analyzed retrospectively; age, sex, presence of intrinsic muscle atrophy, interval from symptom development to surgery, pinch power, the disabilities of the arm, shoulder and hand score and the nerve conduction velocity (NCV). RESULTS: Thirty four (10.4%) patients, being subjected to surgery had the AE. Among 107 patients who had no other known causes, 26 patients had AE. 19 out of 26 patients with AE was male. Average age of patients with AE was significantly younger. The interval from symptom development to surgery in AE patients was significantly shorter. Motor NCV of ulnar nerve at above elbow joint in comparison with that at below elbow joint in AE patient was more significantly decreased (14.3 m/sec vs. 8.3 m/sec). CONCLUSION: The AE in cubital tunnel syndrome is no more rare structure. In younger male patients with rapidly progressive worsening cubital tunnel symptoms, and if there is significant decrease of ulnar motor nerve velocity at above elbow in comparison with at below elbow, the AE should be considered as cause of ulnar neuropathy.

Diagnostic Cutoff Value for Ultrasonography in the Ulnar Neuropathy at the Elbow

OBJECTIVE: To determine the diagnostic cutoff values of ultrasonographic measurements in ulnar neuropathy at the elbow (UNE). METHODS: Twenty-five elbows of 23 patients (9 females, 16 males) diagnosed with UNE and 30 elbows of 30 healthy controls (15 females, 15 males) were included in our study. The ulnar nerve cross-sectional area (CSA) was measured at the Guyon canal, midforearm, and maximal swelling point (MS) around the elbow (the cubital tunnel inlet in healthy controls). CSA measurements of the ulnar nerve at each point, the Guyon canal-to-MS ulnar nerve area ratio (MS/G), and the midforearm-to-MS ulnar nerve ratio (MS/F) were calculated. RESULTS: Among the variables, only CSA at MS, MS/G, and MS/F displayed significant differences between the control and patient groups. The cutoff value for diagnosing UNE was 8.95 mm2 for the CSA at MS (sensitivity 93.8%, specificity 88.3%), 1.99 for the MS/G (sensitivity 75.0%, specificity 73.3%), and 1.48 for the MS/F (sensitivity 93.8%, specificity 95.0%). CONCLUSION: These findings may be helpful to diagnose UNE.

Clinical Implications of Real-Time Visualized Ultrasound-Guided Injection for the Treatment of Ulnar Neuropathy at the Elbow: A Pilot Study

OBJECTIVE: To investigate the feasibility of ultrasound (US)-guided steroid injection by in-plane approach for cubital tunnel syndrome (CuTS), based on symptomatic, morphologic and electrophysiological outcomes. METHODS: A total of 10 patients, who were clinically diagnosed as CuTS and confirmed by an electrodiagnostic study, participated in this study. US-guided injection into the cubital tunnel was performed with 40 mg triamcinolone and 2 mL of 1% lidocaine. Outcomes of the injections were evaluated at pre-injection, 1st week and 4th week after injection. Visual analog scale, self-administered questionnaire of the ulnar neuropathy at the elbow (SQUNE), and McGowan classification were used for clinical evaluation. Cross-sectional area of the ulnar nerve by US and the electrophysiological severity scale through a nerve conduction study were utilized in the evaluation of morphologic and electrophysiological changes. The cross-sectional area of the ulnar nerve was measured at 3 points of condylar, proximal, and distal level of the cubital tunnel. RESULTS: No side effects were reported during the study period. The visual analog scale and cross-sectional area showed a significant decrease at 1st week and 4th week, as compared to baseline (p<0.05). The electrophysiological severity scale was significantly decreased at the 4th week, as compared with baseline and 1st week (p<0.05). Among the quantitative components of the scale, there were statistically significant improvements with respect to the conduction velocity and block. CONCLUSION: The new approach of US-guided injection may be a safe tool for the treatment of CuTS. Symptomatic and morphologic recoveries preceded the electrophysiological improvement.

Comparison of Treatment Methods in Gartland Type III Pediatric Supracondylar Humeral Fracture: Lateral Entry Pin versus Crossed-Pin Technique

PURPOSE: The aim of this study was to compare the results of the lateral entry pin technique and the crossed pin technique in treatment of Gartland type III humerus supracondylar fracture. MATERIALS AND METHODS: Seventeen patients (group I) underwent surgery using the lateral entry pin technique, and 33 patients (group II) underwent surgery using the crossed pin technique for Gartland type III humerus supracondylar fracture in Hanyang University Seoul Hospital between January 2011 and January 2014. Maintenance of reduction was compared between the 2 surgical techniques by measuring changes in Baumann angle and lateral humerocapitellar angle after surgery and after pin removal in groups I and II. In addition, the final carrying angle and level of loss of functional movement were measured for comparison of clinical results between the 2 groups. Occurrence of ulnar nerve palsy in the 2 groups was also examined. RESULTS: The mean Baumann angle and lateral humerocapitellar angle changes were 3.3degrees and 3.7 in group I and 3.1degrees and 3.4degrees in group II, respectively. No statistically significant differences were found between the 2 groups. Clinical results showed that the changes in the final carrying angle and range of motion were 2.9degrees and 2.6degrees in group I and 2.6degrees and 3.0degrees in group II, respectively, indicating no significant differences between the 2 groups. In terms of nerve damage, 1 patient in group II had temporary iatrogenic ulnar nerve palsy. CONCLUSION: The lateral entry pin technique may be regarded as an appropriate treatment that reduces the risk of iatrogenic ulnar nerve palsy and provides satisfactory results in Gartland type III humerus supracondylar fracture patients.

Ulnar Neuropathy Caused by a Schwannoma in the Guyon's Cannal / 대한정형외과학회잡지

Guyon's canal syndrome is a compression neuropathy of the ulnar nerve entrapment at the wrist. Compression of the ulnar nerve at the wrist by a ganglion, lipomas, diseases of the ulnar artery, fractures of the hamate and trauma is a common etiological factor. We report on a rare case of ulnar neuropathy caused by a schwannoma at the level of Guyon's canal.