The posterior interosseous nerve at the proximal forearm: anatomical study and clinical correlation / El nervio interóseo posterior en el antebrazo proximal: estudio anatómico y correlación clínica

SUMMARY: The deep branch of the radial nerve (DBRN) runs through the radial tunnel, which is a muscle-aponeurotic structure that extends from the humeral lateral epicondyle to the distal margin of the supinator muscle (SM). The Posterior Interosseous Nerve (PIN) originates as a direct continuation of the DBRN as it emerges from the SM and supplies most of the muscles of the posterior compartment of the forearm. The PIN can be affected by compressive neuropathies, especially at the "Arcade of Frohse". Its preservation is of special interest in surgical approaches to proximal radius fractures and in compressive syndromes release, for which surgeons must have an adequate anatomical knowledge of its course. This descriptive cross-sectional study evaluated 40 upper limbs of fresh cadavers. The diameters of the DBRN, the length of the radial tunnel, and the distances to the supinator arch, PIN emergence and PIN bifurcation were measured. The deep branch of the radial nerve (DBRN) has a course of 23.8 ± 3.7 mm from its origin to the supinator arch, presenting a diameter of 2.2 ± 0.3 mm at that level. The length of the radial tunnel was 42.2 ± 4 mm. The PIN originated 70.7 ± 3.5 mm distal to the lateral epicondyle. Type I corresponds to the division of the PIN during its journey through the radial tunnel, presenting in 35 % of cases, and Type II corresponds to the division of the PIN distal to its emergence from the radial tunnel presenting in the remaining 65 %. This study enriches the knowledge of the PIN and provides useful reference information on a Latin American mestizo sample. We propose the division pattern of the PIN into two types. Future studies may use this classification not only as a qualitative variable, but also include quantitative morphometric measurements.

El ramo profundo del nervio radial (RPNR) discurre por el túnel radial, que es una estructura músculo- aponeurótica que se extiende desde el epicóndilo lateral del húmero humeral hasta el margen distal del músculo supinador (MS). El nervio interóseo Posterior (NIP) se origina como una continuación directa del RPNR cuando emerge del MS e inerva la mayoría de los músculos del compartimiento posterior del antebrazo. El NIP puede verse afectado por neuropatías compresivas, especialmente en la "Arcada de Frohse". Su conservación es de especial interés en los abordajes quirúrgicos de las fracturas proximales de radio y en la liberación de síndromes compresivos, para lo cual los cirujanos deben tener un adecuado conocimiento anatómico de su curso. Este estudio descriptivo transversal evaluó 40 miembros superiores de cadáveres frescos. Se midieron los diámetros de la RPNR, la longitud del túnel radial y las distancias al arco supinador, la emergencia del NIP y la bifurcación del NIP. El RPNR tenía un recorrido de 23,8 ± 3,7 mm desde su origen hasta el arco supinador, presentando un diámetro de 2,2 ± 0,3 mm a ese nivel. La longitud del túnel radial fue de 42,2 ± 4 mm. El NIP se originó 70,7 ± 3,5 mm distal al epicóndilo lateral. El tipo I corresponde a la división del NIP durante su recorrido por el túnel radial presentándose en el 35 % de los casos, y el tipo II corresponde a la división del NIP distal a su salida del túnel radial presentándose en el 65 % restante. Este estudio enriquece el conocimiento del NIP y proporciona información de referencia útil sobre una muestra de mestizos latinoamericanos. Proponemos el patrón de división del NIP en dos tipos. Futuros estudios pueden utilizar esta clasificación no solo como una variable cualitativa, sino también incluir medidas morfométricas cuantitativas.

Epidemiological study of surgically treated humeral shaft fractures - a 10-year review / Estudo epidemiológico das fraturas diafisárias do úmero tratadas cirurgicamente - uma revisão de 10 anos

ABSTRACT Most epidemiological studies do not exclusively address fractures treated surgically but include those with conservative treatment. In Brazil, few epidemiological studies address fractures prevalence undergoing surgical treatment. Objective: To assess the prevalence, demographics, and associated injuries of surgically treated humeral shaft fractures. Methods: A retrospective study between 2009 and 2019 with patients undergoing osteosynthesis of humeral shaft fracture. Categorical variables were assessed using Fisher's chi-square or exact test, and non-categorical variables were assessed using the unpaired t-test. A significance level of 5% was adopted. Results: A total of 115 patients were evaluated. Mean age was 37.9 ± 15.6 years, with a male predominance (66.9%) due to car accidents. The most prevalent fracture type was 12 A3. Open fracture prevalence was 11.3%. Radial nerve damage prevalence was 33% and low-energy trauma was twice as likely. Conclusion: Surgically treated humeral shaft fractures were more prevalent in men, young, and related to high-energy trauma, with a transverse line pattern. Fractures secondary to low-energy trauma had a greater association with radial nerve injury. Level of Evidence III, Epidemiological, Retrospective Study.

RESUMO A maior parcela dos estudos epidemiológicos não aborda exclusivamente as fraturas tratadas cirurgicamente, mas engloba as de tratamento conservador. No Brasil existem poucos estudos epidemiológicos que versam sobre a prevalência das fraturas submetidas ao tratamento cirúrgico. Objetivo: Avaliar a prevalência, os dados demográficos e as lesões associadas das fraturas da diáfise do úmero tratadas cirurgicamente. Métodos: Estudo retrospectivo conduzido entre 2009 e 2019, com pacientes submetidos a osteossíntese de fratura diafisária do úmero. As variáveis categóricas foram testadas pelo teste qui-quadrado ou teste exato de Fisher, enquanto as não categóricas foram medidas pelo teste t não pareado. Adotou-se nível de significância de 5%. Resultados: Foram avaliados 115 pacientes. A média de idade foi de 37,9 ± 15,6 anos, com uma predominância de pacientes do sexo masculino (66,9%) devido a acidentes automobilísticos. A fratura tipo 12 A3 foi a mais prevalente. A prevalência de fratura exposta foi de 11,3%. A lesão nervo radial ocorreu em 33%, principalmente em traumas de baixa energia. Conclusão: As fraturas diafisárias do úmero tratadas cirurgicamente foram mais prevalentes em homens jovens e relacionadas a traumas de alta energia, com padrão de traço transverso. Fraturas secundárias e traumas de baixa energia tiveram maior associação com lesão do nervo radial. Nível de Evidência III, Estudo Epidemiológico, Retrospectivo.

Anatomical Study of Radial Tunnel and its Clinical Implications in Compressive Syndromes / Estudo anatômico do túnel radial e suas implicações nas síndromes compressivas

Abstract Objective The purpose of the present study was to analyze the structures in the radial tunnel that can cause posterior interosseous nerve entrapment. Methods A total of 30 members of 15 adult cadavers prepared by intra-arterial injection of a 10% solution of glycerol and formalin were dissected. All were male, belonging to the laboratory of anatomy of this institution. Results The branch for the supinator muscle originated from the posterior interosseous nerve in all limbs. We identified the Frohse arcade with a well-developed fibrous constitution in 22 of the 30 dissected limbs (73%) and of muscular constitution in 8 (27%). The distal margin of the supinator muscle presented fibrous consistency in 7 of the 30 limbs (23.5%) and muscular appearance in 23 (76.5%). In the proximal margin of the extensor carpi radialis brevis muscle, we identified the fibrous arch in 18 limbs (60%); in 9 (30%) we noticed the arcade of muscular constitution; in 3 (10%) there was only the radial insertion, so that it did not form the arcade. Conclusion The Frohse arcade and the arcade formed by the origins of the extensor carpi radialis brevis are normal anatomical structures in adult cadavers. However, from the clinical point of view, these structures have the potential to cause entrapment of the posterior interosseous nerve.

Resumo Objetivo O objetivo do presente estudo foi analisar as estruturas contidas no túnel radial que podem causar neuropatia compressiva do nervo interósseo posterior. Métodos Foram dissecados 30 membros de 15 cadáveres adultos, preparados por injeção intra-arterial de uma solução de glicerina e formol a 10%. Todos do sexo masculino, pertencentes ao laboratório de anatomia desta instituição. Resultados O ramo para o músculo supinador originou-se do nervo interósseo posterior em todos os membros. Identificamos a arcada de Frohse com uma constituição fibrosa bem desenvolvida em 22 dos 30 membros dissecados (73%) e de constituição muscular em 8 (23%) A margem distal do músculo supinador apresentou consistência fibrosa em 7 dos 30 membros (23,5%) e uma aparência muscular em 23 (76,5%). Na margem proximal do músculo extensor radial curto do carpo, identificamos a arcada fibrosa em 18 membros (60%); em 9 (30%), notamos a arcada de constituição muscular; e em três (10%) havia apenas a inserção radial, de maneira que não formava a arcada. Conclusão A arcada de Frohse e a arcada formada pelas origens do músculo extensor radial curto do carpo são estruturas anatômicas normais em cadáveres adultos. No entanto, sob o ponto de vista clínico, essas estruturas têm potencial para causar a compressão do nervo interósseo posterior.

Investigation of the Diagnostic Value of Ultrasonography for Radial Neuropathy Located at the Spiral Groove

OBJECTIVE: To determine a diagnostic cut-off value for the cross-sectional area (CSA) of the radial nerve using ultrasonography for radial neuropathy located at the spiral groove (SG). METHODS: Seventeen patients with electrodiagnostic evidence of radial neuropathy at the SG and 30 healthy controls underwent ultrasonography of the radial nerve at the SG . The CSAs at the SG were compared in the patient and control groups. The CSA at the SG between the symptomatic and asymptomatic sides (ΔSx–Asx and Sx/Asx, respectively) were analyzed to obtain the optimal cut-off value. The relationship between the electrophysiological severity of radial neuropathy and CSA was also evaluated. RESULTS: Among the variables examined, there were statistically significant differences in the CSA between the patient and control groups, ΔSx–Asx, and Sx/Asx at the SG. In a receiver operating characteristics analysis, the cut-off CSA was 5.75 mm² at the SG (sensitivity 52.9%, specificity 90%), 1.75 mm² for ΔSx–Asx (sensitivity 58.8%, specificity 100%), and 1.22 mm² for Sx/Asx (sensitivity 70.6%, specificity 93.3%) in diagnosing radial neuropathy at the SG. There was no significant correlation between CSA and electrophysiological severity score for either patient group. CONCLUSION: The reference value obtained for CSA of the radial nerve at the SG may facilitate investigation of radial nerve pathologies at the SG.

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.

Radial Neuropathy after Cryolipolysis

Cryolipolysis has become available for the noninvasive reduction of adipose tissue. A 33-year-old woman presented with wrist drop of the right arm that had first appeared 7 days previously. She had undergone cryolipolysis on both upper arms immediately prior to the onset of symptoms. A nerve conduction study showed radial neuropathy proximal to the elbow, and ultrasonography revealed focal swelling of the radial nerve at the spiral groove. Although cryolipolysis has been known as a safe method, nerve injury can result from compression and/or hypothermia during the procedure.

A Rare Complication after Latissimus Dorsi Flap Breast Reconstruction: Radial Nerve Palsy

Among autologous breast reconstruction techniques, breast reconstruction using the latissimus dorsi musculocutaneous flap is widely used, offering advantages including the relative simplicity of the procedure and the reliable and consistent vascularity of the flap. Accordingly, more than 500 cases have been performed in the past 8 years at Kyungpook National University Medical Center. This study reports on a rare case involving a radial nerve neuropathy complication which was experienced for the first time at the medical center. The current case demonstrates that in addition to common complications, such as seroma of the donor site and scarring, additional intraoperative complications in areas unrelated to the surgical site can occur, including radial nerve neuropathy in the opposite arm.

Numbness after Transradial Cardiac Catheterization: the Results from a Nerve Conduction Study of the Superficial Radial Nerve

BACKGROUND AND OBJECTIVES: Numbness on the hand occurs infrequently after a transradial cardiac catheterization (TRC). The symptom resembles that of neuropathy. We, therefore, investigated the prevalence, the predicting factors and the presence of neurological abnormalities of numbness, using a nerve conduction study (NCS). SUBJECTS AND METHODS: From April to December 2013, all patients who underwent a TRC were prospectively enrolled. From among these, the patients who experienced numbness on the ipsilateral hand were instructed to describe their symptoms using a visual analogue scale; subsequently, NCSs were performed on these patients. RESULTS: Of the total 479 patients in the study sample, numbness occurred in nine (1.8%) following the procedure. The NCS was performed for eight out of the nine patients, four (50%) of which had an abnormal NCS result at the superficial radial nerve. A larger sheath and history of myocardial infarction (p=0.14 and 0.08 respectively) tended towards the occurrence of numbness; however, only the use of size 7 French sheaths was an independent predictor for the occurrence of numbness (odds ratio: 5.50, 95% confidence interval: 1.06-28.58, p=0.042). The symptoms disappeared for all patients but one, within four months. CONCLUSION: A transient injury of the superficial radial nerve could be one reason for numbness after a TRC. A large sheath size was an independent predictor of numbness; therefore, large sized sheaths should be used with caution when performing a TRC.

The Usefulness of Proximal Radial Motor Conduction in Acute Compressive Radial Neuropathy

BACKGROUND AND PURPOSE: The objective of this study was to determine diagnostic and prognostic values of proximal radial motor conduction in acute compressive radial neuropathy. METHODS: Thirty-nine consecutive cases of acute compressive radial neuropathy with radial conduction studies-including stimulation at Erb's point-performed within 14 days from clinical onset were reviewed. The radial conduction data of 39 control subjects were used as reference data. RESULTS: Thirty-one men and eight women (age, 45.2+/-12.7 years, mean+/-SD) were enrolled. All 33 patients in whom clinical follow-up data were available experienced complete recovery, with a recovery time of 46.8+/-34.3 days. Partial conduction block was found frequently (17 patients) on radial conduction studies. The decrease in the compound muscle action potential area between the arm and Erb's point was an independent predictor for recovery time. CONCLUSIONS: Proximal radial motor conduction appears to be a useful method for the early detection and prediction of prognosis of acute compressive radial neuropathy.

Compressive Radial Neuropathy Developed Under a Fibrotic Band Associated With Rhabdomyolysis and Successfully Treated With Surgery

A 34-year-old male patient visited the emergency room with complaint of right wrist drop and foot drop. The day before, he was intoxicated and fell asleep in a room containing barbeque briquettes; After waking up, he noticed that his right wrist and foot were dropped. Upon physical examination, his right wrist extensor, thumb extensor, ankle dorsiflexor, and big toe extensor showed Medical Research Council (MRC) grade 1 power. The initial laboratory tests suggested rhabdomyolysis induced by unrelieved pressure on the right side during sleep. Right foot drop was improved after conservative care and elevated muscle enzyme became normalized with hydration therapy with no resultant acute renal failure. However, the wrist drop did not show improvement and a hard mass was palpated on the follow-up physical examination. Ultrasonography and magnetic resonance imaging studies were conducted and an abnormal mass in the lateral head of the tricep was detected. Axonopathy was suggested by the electrodiagnostic examination. A surgical decompression was done and a fibrotic cord lesion compressing the radial nerve was detected. After adhesiolysis, his wrist extensor power improved to MRC grade 4. Herein, we describe a compressive radial neuropathy associated with rhabdomyolysis successfully treated with surgery and provide a brief review of the related literature.

Systematic review of radial nerve palsy associated with humeral shaft fracture / 中华骨科杂志

Objective To review the clinical management of the radial nerve palsy (RNP) associated with humeral shaft fractures via systematically reviewing the published available articles, and develope an algorithm to guide management for RNP. Methods Using PubMed, Datastar and Cochrane Database, web based databases were searched for radial nerve palsy associated with humeral shaft fractures in the past 40 years, and manual searches of the bibliographic sections of electronically identified papers were done to identify further papers. Meticulous data extraction and meta-analysis was performed according to a preset protocol. Results In 391 citations initially identified, 35 papers, which included a total of 1045 RNP patients, met all eligibility criteria. The overall RNP incidence after humeral shaft fractures in 21 papers was 11.8% (532/4517). The incidence of RNP in middle 1/5 and middle-distal 1/5 of the humeral shaft fracture was significantly higher than that in other parts. Transverse and spiral fractures were more likely to sustain RNP than oblique and comminuted fracture patterns(P