Anterior Interosseous Syndrome Research Articles

Incidence of complications among operative pediatric supracondylar humerus fractures using medial and lateral pins: a safe technique for percutaneous medial pin placement.

Cross-pinning of displaced pediatric supracondylar elbow fractures offers a superior stability construct. However, there is a reluctance to use this construct by closed means because of the risk of iatrogenic ulnar nerve injuries associated with percutaneous medial pin placement. This study describes a safe technique for closed reduction percutaneous with medial pin placement. This study reviewed the clinical charts of 232 pediatric patients who underwent closed reduction with cross-pinning of Gartland type II and III supracondylar fractures from 2000 to 2022 at a single institution. All surgeries were performed by the same attending surgeon at the same institution, with the same technique of medial pin placement. The inpatient and outpatient notes were used to record patient demographic information, fracture classification, and postoperative complications. A total of 232 pediatric patients [114 boys, 118 girls; mean age: 5.8 (range: 1-14) years] with Gartland type II (n = 97) and III (n = 135) supracondylar fractures were included in the study. There were a total of seven (3.02%) postoperative complications: four (1.7%) ulnar neuropathies, two (0.86%) pin site infections, and one (0.43%) anterior interosseous nerve palsy. All documented postoperative complications were resolved by the 3-month follow-up visit. There were no complications of deep infection, malunion, or nonunion. With the proper technique, closed reduction with percutaneous medial pin fixation of pediatric supracondylar fractures is safe and produces excellent postoperative outcomes. Level of Evidence: Level IV, case series.

Isolated Palsy of the Anterior Interosseous Nerve to Flexor Pollicis Longus, Magnetic Resonance Imaging and Clinical Correlation: A Case Report.

Anterior interosseous nerve (AIN) palsy is an uncommon, though well-described, clinical entity. When isolated to the thumb, it can be confused with atraumatic rupture of the flexor pollicis longus (FPL) tendon. A 57-year-old man experienced atraumatic onset of difficulty flexing the distal interphalangeal thumb joint. Magnetic resonance imaging (MRI) demonstrated denervation edema of the FPL, suggesting atypical AIN palsy. Resolution of symptoms and MRI findings occurred concomitantly with nonoperative treatment. Atypical AIN palsy limited to the FPL is a rare clinical entity whose diagnosis can be supported with MRI. Here, we report a successful case of nonoperative management.

Fascicular Involvement of the Median Nerve Trunk in the Upper Arm: Manifestation as Anterior Interosseous Nerve Syndrome With Unique Imaging Features.

Selective fascicular involvement of the median nerve trunk above the elbow leading to anterior interosseous nerve (AIN) syndrome is a rare form of peripheral neuropathy. This condition has recently garnered increased attention within the medical community owing to advancements in imaging techniques and a growing number of reported cases. In this article, we explore the topographical anatomy of the median nerve trunk and the clinical features associated with AIN palsy. Our focus extends to unique manifestations captured through MRI and ultrasonography (US) studies, highlighting noteworthy findings, such as nerve fascicle swelling, incomplete constrictions, hourglass-like constrictions, and torsions, particularly in the posterior/posteromedial region of the median nerve. Surgical observations have further enhanced the understanding of this complex neuropathic condition. High-resolution MRI not only reveals denervation changes in the AIN and median nerve territories but also illuminates these alterations without the presence of compressing structures. The pivotal roles of high-resolution MRI and US in diagnosing this condition and guiding the formulation of an optimal treatment strategy are emphasized.

Ultrasonographic Evaluation of the Needle Insertion Site for the Flexor Pollicis Longus Using the Flexor Carpi Radialis Tendon

Objective: In needle electromyography (EMG), the flexor pollicis longus (FPL) muscle is important for diagnosing anterior interosseous nerve syndrome and proximal median neuropathy. However, different methods have been proposed for needle EMG placement in the FPL. This study aimed to determine the optimal needle insertion position for the examination of the FPL via needle EMG under ultrasound guidance.Methods: This study included 15 men (30 upper limbs) and 13 women (26 upper limbs). At the mid-forearm level, the angles between the vertical line descending from the radial side of the flexor carpi radialis (FCR) tendon and radial artery (angle A), flexor digitorum profundus 1 (angle B), and median nerve (MN) (angle C) were measured. Angle D was defined as the average of angles A and B.Results: The median value of angle D was –19.8°. The probability of radial artery injury at an angle D of 10° was 10.7%. The likelihood of MN injury was 7.1%.Conclusion: Needle insertion through the FCR tendon is relatively safe, although the risk of neurovascular injury remains. Therefore, an ultrasound examination could be considered as an assistive method.

Pronator Syndrome and other Nerve Compressions that Mimic Carpal Tunnel Syndrome a Case Report and Literature Review

The resolution of small to intermediate-sized anomalies affecting the craniofacial region can pose a formidable problem Proximal neuropathy of the median nerve (MN) is a relatively rare condition, accounting for approximately 1% of all compressive neuropathies affecting the upper limb. The existing body of literature documents two distinct clinical presentations, which are based upon the location of entrapment. These presentations are commonly referred to as pronator teres (PT) syndrome and anterior interosseous nerve (AIN) syndrome. Pronator teres syndrome, also known as median nerve compression in the upper forearm, manifests as a constellation of clinical manifestations and indications. Carpal tunnel syndrome is a dynamic condition that is commonly characterized by the compression of the median nerve within the carpal tunnel. Although relatively uncommon when compared to carpal tunnel syndrome, pronator syndrome and anterior interosseous nerve syndrome are conditions involving compression of the proximal median nerve. These conditions may be considered as potential diagnoses when a patient with carpal tunnel syndrome does not show improvement following conservative or surgical treatment. The process of differential diagnosis primarily relies on the evaluation of symptoms, the analysis of paresthesia patterns, and the identification of distinct patterns of muscle weakness. Initial management of all patients should primarily involve nonsurgical treatment modalities. However, it has been demonstrated through empirical evidence that surgical intervention may produce favorable outcomes. Many surgical methodologies have been established, with the majority of outcome data derived from retrospective case series. A full comprehension of the anatomical structure of the median nerve, possible points of compression, and distinctive clinical manifestations of carpal tunnel syndrome (CTS) is imperative for physicians in order to correctly identify and successfully manage their patients.

Persistent Hourglass Constriction in Recovered Anterior Interosseous Nerve Palsy Due to Neuralgic Amyotrophy: A Case Report.

The current articles recommended the interfascicular neurolysis for anterior interosseous nerve (AIN) palsy with hourglass-like fascicular constrictions (FCs) detected by ultrasonography or surgical exploration to realign to the fascicular torsion for those who failed to recover spontaneously. We present the case report of spontaneous AIN palsy recovered after conservative treatment; however, ultrasonographic findings showed persistent FCs of AIN in the arm at the beginning, at 6 weeks, and subsequent 3-year follow-ups, even after complete clinical recovery of palsy. This finding calls into question the current notion that AIN paralysis is due to FCs and that neurolysis is the best surgical treatment when spontaneous recovery does not occur for a considerable observation period. Level of Evidence: Level V (Therapeutic).

Kiloh-Nevin syndrome: an unusual cause of forearm pain.

The popularity of weight training, bodybuilding and general physical conditioning has led to an increased rate of musculoskeletal injuries, such as nerve compression caused by muscle hypertrophy and, stretching of nerves peripherally. We present a case of anterior interosseous nerve (AIN) entrapment syndrome/neuropathy otherwise known as Kiloh-Nevin syndrome in a 22-year-old weightlifter. Knowledge of this injury is paramount for practitioners to increase awareness among athletes and bodybuilders.

Anterior interosseous nerve syndrome following infection with COVID-19: a case report

BackgroundVarious neurological manifestations associated with coronavirus disease 2019 have been increasingly reported. Herein, we report a rare case of anterior interosseous nerve syndrome, which occurred 5 days after the onset of coronavirus disease 2019.Case presentationA 62-year-old Asian woman with a history of coronavirus disease 2019 who developed a complete motor deficit in the left flexor pollicis longus and pronator quadratus without sensory deficits. The symptoms appeared as a sudden onset fatigue and severe pain of the left arm, 5 days after the onset of coronavirus disease 2019. She noticed paralysis of the left thumb at 2 weeks after the onset of coronavirus disease 2019. Electromyography assessment of the anterior interosseous nerve-dominated muscles revealed neurogenic changes such as positive sharp wave and fibrillation in flexor pollicis longus and pronator quadratus, confirming the diagnosis of anterior interosseous nerve syndrome. There were no other diseases that could have resulted in peripheral nerve palsy. We performed a functional reconstruction surgery of the thumb by tendon transfer from the extensor carpi radialis longus to the flexor pollicis longus. The patient reported a good patient-reported outcome (2.27 points in QuickDASH Disability/Symptom scoring and 5 points in Hand20 scoring) at final follow-up (1 year after the surgery).ConclusionThis case highlights the need for vigilance regarding the possible development of anterior interosseous nerve syndrome in patients with coronavirus disease 2019. Tendon transfer from extensor carpi radialis longus to flexor pollicis longus can provide good functional recovery for unrecovered motor paralysis after anterior interosseous nerve syndrome.

Anterior Interosseous Nerve Syndrome.

Anterior interosseous nerve syndrome (AINS) is a rare form of peripheral neuropathy which involves disruption of the anterior interosseous nerve. The pathophysiology of AINS remains unclear. AINS typically initially presents with forearm pain and may gradually progress to palsy of the deep muscles of the anterior forearm. Diagnosis of AINS requires thorough patient history and physical exam. EMG is the preferred diagnostic study and classically reveals abnormal activity and prolonged latency periods within the evoked action potentials of the FPL and PQ. Due to the self-limiting nature of AINS, there is general agreement that conservative and symptomatic management should be explored for up to 6 months as first line therapy, which usually includes analgesics and nonsteroidal anti-inflammatory drugs, contracture prevention, hand therapy, and hand splinting. Surgical options such as internal neurolysis and minimally invasive endoscopic decompression may be explored if functional recovery from conservative management is limited.

Proximal Median Nerve Compression in the Differential Diagnosis of Carpal Tunnel Syndrome.

Carpal tunnel syndrome (CTS) is the most common median nerve compression neuropathy. Its symptoms and clinical presentation are well known. However, symptoms at median nerve distribution can also be caused by a proximal problem. Pronator syndrome (PS) and anterior interosseous nerve syndrome (AINS) with their typical characteristics have been thought to explain proximal median nerve problems. Still, the literature on proximal median nerve compressions (PMNCs) is conflicting, making this classic split too simple. This review clarifies that PMNCs should be understood as a spectrum of mild to severe nerve lesions along a branching median nerve, thus causing variable symptoms. Clear objective findings are not always present, and therefore, diagnosis should be based on a more thorough understanding of anatomy and clinical testing. Treatment should be planned according to each patient’s individual situation. To emphasize the complexity of causes and symptoms, PMNC should be named proximal median nerve syndrome.

Compression Neuropathies of the Upper Extremity: A Review

Compressive neuropathies of the forearm are common and involve structures innervated by the median, ulnar, and radial nerves. A thorough patient history, occupational history, and physical examination can aid diagnosis. Electromyography, X-ray, and Magnetic Resonance Imaging may prove useful in select syndromes. Generally, first line therapy of all compressive neuropathies consists of activity modification, rest, splinting, and non-steroidal anti-inflammatory drugs. Many patients experience improvement with conservative measures. For those lacking adequate response, steroid injections may improve symptoms. Surgical release is the last line therapy and has varied outcomes depending on the compression. Carpal Tunnel syndrome (CTS) is the most common, followed by ulnar tunnel syndrome. Open and endoscopic CTS release appear to have similar outcomes. Endoscopic release appears to incur decreased cost baring a low rate of complications, although this is debated in the literature. Additional syndromes of median nerve compression include pronator syndrome (PS), anterior interosseous syndrome, and ligament of Struthers syndrome. Ulnar nerve compressive neuropathies include cubital tunnel syndrome and Guyon’s canal. Radial nerve compressive neuropathies include radial tunnel syndrome and Wartenberg’s syndrome. The goal of this review is to provide all clinicians with guidance on diagnosis and treatment of commonly encountered compressive neuropathies of the forearm.

Unique case of anterior interosseous nerve injury following distal volar radial plating: A case report

Trauma itself, surgery, nerve entrapments, amyotrophic neuropathy, or neuritis may result in anterior interosseous nerve (AIN) palsy. A 76-year-old woman who was operated for distal end radius fracture with plating was referred back referred back to the clinic by her general practitioner with complaints of inability to flex the interphalangeal joint of the thumb and index finger approximately 3 years after the index surgery. The proximal interphalangeal joint flexion (flexor digitorum superficialis) of the index finger was intact and the pinch power was reduced. She had normal function of her other forearm and hand muscles. Ultrasonography and nerve conduction velocity (NCV) studies were done to investigate further to rule out either tendon flexor pollicis longus (FPL) or nerve injury (AIN). NCV studies reported subacute denervation within the FPL. The patient recovered to near normal without any surgical intervention in 18 months. Literature reported various treatment options in the form of conservative as well as surgical depending on the cause and evidence of recovery.

Current Concepts of Anterior Interosseous Nerve Syndrome

The causes and treatment of anterior interosseous nerve syndrome have not been established yet. Two causes are known, as a result of compressive neuropathy and as a result of neuralgic amyotrophy. An hourglass-like constriction found in the main trunk of the median nerve suggests a new paradigm for the cause and treatment of anterior interosseous nerve syndrome. It is necessary to differentiate it from other diseases through a meticulous physical examination, and surgical treatment is recommended only when there are no other related neurological lesions and no improvement despite conservative treatment for more than 6 months.

Neuralgic amyotrophy.

This review focuses on the current insights and developments in neuralgic amyotrophy (NA), an auto-immune multifocal peripheral nervous system disorder that leaves many patients permanently impaired if not recognized and treated properly. NA is not as rare as previously thought. The phenotype is broad, and recent nerve imaging developments suggest that NA is the most common cause of acute anterior or posterior interosseous nerve palsy. Phrenic nerve involvement occurs in 8% of all NA patients, often with debilitating consequences. Acute phase treatment of NA with steroids or i.v. immunoglobulin may benefit patients. Long-term consequences are the rule, and persisting symptoms are mainly caused by a combination of decreased endurance in the affected nerves and an altered posture and movement pattern, not by the axonal damage itself. Patients benefit from specific rehabilitation treatment. For nerves that do not recover, surgery may be an option. NA is not uncommon, and has a long-term impact on patients' well-being. Early immunomodulating treatment, and identifying phrenic neuropathy or complete nerve paralysis is important for optimal recovery. For persistent symptoms a specific treatment strategy aiming at regaining an energy balance and well-coordinated scapular movement are paramount.

Coexistence of two accessory flexor pollicis longus heads or coexistence of two-headed flexor pollicis longus with an unrecognized anatomical structure?

The flexor pollicis longus (FPL) is located in the anterior compartment of the forearm. It is morphologically variable in both point of origin and insertion. An additional head of the FPL can lead to anterior interosseous syndrome. This report presents a morphological variation of the FPL (additional head in proximal attachment and bifurcated tendinous insertion in distal attachment) and an unrecognized structure that has not so far been described in the literature. This structure originates in six heads (attached to the FPL or interosseous membrane) that merge together, and inserts on to the FPL. All the variations noted have clinical significance, ranging from potential nerve compression to prevention of tendon rupture.

Anterior interosseous nerve palsy caused by Parsonage-Turner syndrome.

Anterior interosseous nerve palsy caused by Parsonage-Turner syndrome.

Lesions of the anterior interosseous nerve: differentiating between compression neuropathy and neuritis

In cases of anterior interosseous nerve (AIN) syndrome, it is often difficult to differentiate between compression neuropathy and neuritis. This review analyses the clinical aspects of the neuritic AIN syndrome and the different diagnostic tools for securing the diagnosis and differentiating the condition from compression neuropathy. Based on these data, the current therapeutic options are proposed. The AIN syndrome often results from neuritis of the AIN fascicles within the trunk of the median nerve. The differentiation between neuritis and compression neuropathy of the AIN is based on dedicated neurophysiological examinations as well as nerve sonography and MRI neurography. Although conservative treatment is the gold standard, microsurgical interventions have become more important in recent years. A dedicated diagnostic workup of the AIN syndrome is paramount for optimal treatment. Conservative treatment remains the standard to date. However, if torsions and constrictions of nerve fascicles are detected, intrafascicular neurolysis should be considered, as current research shows the potential for an improved outcome in such cases.

Median nerve entrapment syndrome in the elbow and proximal forearm. Anatomic causes and results for a 55-case surgical series at a mean 7 years’ follow-up

BackgroundProximal median nerve (MN) neuropathy represents 1% of upper-limb compressive neuropathies. The literature reports two clinical presentations, depending on the location of the entrapment: pronator teres (PT), and anterior interosseous nerve (AIN) syndrome. HypothesisThere is no correlation between symptoms and location of proximal compressive structures on the MN trunk or AIN. Patients and methodsClinical and paraclinical data from 55 surgical MN releases around the elbow and proximal forearm were analyzed retrospectively. Mean age at diagnosis was 56±15years. Preoperative sensory and motor deficit signs were present in 89% of cases. Reduced MN conduction velocity and/or neurogenic anomalies in the MN territory were present in 94% of cases. Intraoperative details of compressive structures were collected. Patients were followed up in consultation to assess progression of symptoms and deficits. ResultsMean follow-up was 84±70months. Objective motor deficit signs persisted in 18 of the 35 patients (18 cases), and objective sensory signs in 19 cases. A compressive anatomical structure was systematically found. There were at least two MN entrapment sites in 13 cases (24%). No isolated AIN entrapment was found. There was a significant correlation between symptom duration and persistence of objective sensory signs (p=0.002). DiscussionThere was no correlation between entrapment site and clinical signs on examination. Surgery requires exploring all potential entrapment sites. Improvement may be incomplete in case of late treatment. Level of evidenceIV; retrospective study.

Incidence and Morphology of Accessory Head of Flexor Pollicis Longus in Telangana, India

Introduction: Flexor Pollicis Longus (FPL) may have accessory slips which arise from lateral or medial border of coronoid process of ulna and medial epicondyle of humerus. The accessory slip of FPL is known as Accessory Head of Flexor Pollicis Longus (AHFPL) or Gantzer’s Muscle. Aim: To study the incidence and morphology of AHFPL and the relationship of AHFPL with Median Nerve (MN) and Anterior Interosseous Nerve (AIN) in Telangana population. Materials and Methods: The present study was an observational study, conducted on 25 cadavers (21 male, 4 female) for a period of 18 months (July 2019-December 2020) in Department of Anatomy, Osmania Medical College, Hyderabad, Telangana, India. The cadavers which were used for dissection by first year MBBS students were included in the present study and the cadavers with scars, deformities and with congenital anomalies were excluded from the present study. Results: In the present study, AHFPL was found in 58% upper limbs. It was bilateral in 40%, unilateral in 18% upper limbs. The shape of AHFPL was fusiform in majority of (86.2%) upper limbs. It originated from the coronoid process of ulna in 62% and from medial epicondyle of humerus in 38% upper limbs, inserted by joining with tendon of FPL. The AHFPL was innervated by AIN in all the cases and this nerve was located posterior to AHFPL in majority of (83%) upper limbs, posterolateral in few (17%) upper limbs. The MN was related anterior to the AHFPL in most of the upper limbs. Conclusion: In the present study, AHFPL was found in 58% upper limbs. Bilateral occurrence (40%) was common than unilateral (18%). The presence of AHFPL can cause AIN syndrome, pronator teres syndrome. The knowledge of AHFPL would be useful for both physicians and surgeons to know the aetiology and management of compression neuropathy/nerve entrapment syndrome.

Anterior Interosseous Nerve Syndrome Reconsidered: A Critical Analysis Review.

Anterior interosseous nerve syndrome (AINS) represents a form of neuralgic amyotrophy (Parsonage-Turner syndrome). AINS does not originate from external compression of the AIN in the forearm. Fascicular constrictions (FCs) of the median nerve are identified within the anterior interosseous fascicular group at or above the medial epicondyle. Spontaneous recovery is not ensured, leaving up to 30% of patients with permanent weakness or palsy. Fascicular microneurolysis of the median nerve, performed at or above the elbow, is a treatment option for patients who do not recover spontaneously.