Quadrilateral Space Syndrome: Diagnosis and Clinical Management

Under pressure: a head-to-toe review of vascular compression syndromes

Vascular compression syndromes are a group of conditions resulting from mechanical compression of blood vessels by adjacent structures leading to compromised blood flow and various associated symptoms. They frequently affect young, otherwise healthy individuals and are often underdiagnosed due to their rarity and vague clinical manifestations. Achieving an accurate diagnosis depends on the integration of clinical presentation and imaging findings. Imaging modalities including color doppler ultrasound, computed tomography angiography, magnetic resonance angiography, and catheter-directed digital subtraction angiography are essential for diagnosis and management. Dynamic imaging is crucial in eliciting findings due to the positional nature of many of these syndromes. In this paper, we will present a "head-to-toe" overview of vascular compression syndromes including Vascular Eagle Syndrome, Vascular Thoracic Outlet Syndrome, Quadrilateral Space Syndrome, Hypothenar Hammer Syndrome, Median Arcuate Ligament Syndrome, Renal Artery Entrapment Syndrome, Left Renal Vein Compression/Nutcracker Syndrome, May-Thurner Syndrome, Adductor Canal Syndrome, and Popliteal Artery Entrapment Syndrome. Treatment is variable but typically involves a combination of conservative and surgical management. Surgical approaches focus on decompression of affected neurovascular structures. Endovascular treatment alone is rarely recommended. We aim to equip general radiologists with the knowledge needed to accurately diagnose patients with vascular compression syndromes, allowing for timely treatment.

Upper-limb neurovascular compression, pectoralis minor and quadrilateral space syndromes: A narrative review of current literature

Pectoralis minor syndrome (PMS) and quadrilateral space syndrome (QSS) are uncommon neurovascular compression disorders affecting the upper extremity. PMS involves compression under the pectoralis minor muscle, and QSS results from compression in the quadrilateral space-both are classically observed in overhead-motion athletes. Diagnosing PMS and QSS may be challenging due to variable presentations and similarities with other, more common, upper-limb pathologies. Although there is no gold standard diagnostic, local analgesic muscle-block response in a patient with the appropriate clinical context is often all that is required for an accurate diagnosis after excluding more common etiologies. Treatment ranges from conservative physical therapy to decompressive surgery, which is reserved for refractory cases or severe, acute vascular presentations. Decompression generally yields favorable outcomes, with most patients experiencing significant relief and restored baseline function. In conclusion, PMS and QSS, although rare, can cause debilitating upper-extremity symptoms; accurate diagnosis and appropriate treatment offer excellent outcomes, alleviating pain and disability.

Diagnosis and management of thoracic outlet syndrome in athletes

The physical demands of sports can place patients at elevated risk of use-related pathologies, including thoracic outlet syndrome (TOS). Overhead athletes in particular (eg, baseball and football players, swimmers, divers, and weightlifters) often subject their subclavian vessels and brachial plexuses to repetitive trauma, resulting in venous effort thrombosis, arterial occlusions, brachial plexopathy, and more. This patient population is at higher risk for Paget-Schroetter syndrome, or effort thrombosis, although neurogenic TOS (nTOS) is still the predominant form of the disease among all groups. First-rib resection is almost always recommended for vascular TOS in a young, active population, although a surgical benefit for patients with nTOS is less clear. Practitioners specializing in upper extremity disorders should take care to differentiate TOS from other repetitive use-related disorders, including shoulder orthopedic injuries and nerve entrapments at other areas of the neck and arm, as TOS is usually a diagnosis of exclusion. For nTOS, physical therapy is a cornerstone of diagnosis, along with response to injections. Most patients first undergo some period of nonoperative management with intense physical therapy and training before proceeding with rib resection. It is particularly essential for ensuring that athletes can return to their baselines of flexibility, strength, and stamina in the upper extremity. Botulinum toxin and lidocaine injections in the anterior scalene muscle might predict which patients will likely benefit from first-rib resection. Athletes are usually satisfied with their decisions to undergo first-rib resection, although the risk of rare but potentially career- or life-threatening complications, such as brachial plexus injury or subclavian vessel injury, must be considered. Frequently, they are able to return to the same or a higher level of play after full recovery.

A Surgical Framework for the Management of Incomplete Axillary Nerve Injuries

BACKGROUND

 Axillary nerve injury is the most common nerve injury affecting shoulder function. Nerve repair, grafting, and/or end-to-end nerve transfers are used to reconstruct complete neurotmetic axillary nerve injuries. While many incomplete axillary nerve injuries self-resolve, axonotmetic injuries are unpredictable, and incomplete recovery occurs. Similarly, recovery may be further inhibited by superimposed compression neuropathy at the quadrangular space. The current framework for managing incomplete axillary injuries typically does not include surgery.

METHODS

 This study is a retrospective analysis of 23 consecutive patients with incomplete axillary nerve palsy who underwent quadrangular space decompression with additional selective medial triceps to axillary end-to-side nerve transfers in 7 patients between 2015 and 2019. Primary outcome variables included the proportion of patients with shoulder abduction M3 or greater as measured on the Medical Research Council (MRC) scale, and shoulder pain measured on a Visual Analogue Scale (VAS). Secondary outcome variables included pre- and postoperative Disabilities of the Arm, Shoulder, and Hand Questionnaire (DASH) scores.

RESULTS

 A total of 23 patients met the inclusion criteria and underwent nerve surgery a mean 10.7 months after injury. Nineteen (83%) patients achieved MRC grade 3 shoulder abduction or greater after intervention, compared with only 4 (17%) patients preoperatively (p = 0.001). There was a significant decrease in VAS shoulder pain scores of 4.2 ± 2.5 preoperatively to 1.9 ± 2.4 postoperatively (p < 0.001). The DASH scores also decreased significantly from 48.8 ± 19.0 preoperatively to 30.7 ± 20.4 postoperatively (p < 0.001). Total follow-up was 17.3 ± 4.3 months.

CONCLUSION

 A surgical framework is presented for the appropriate diagnosis and surgical management of incomplete axillary nerve injury. Quadrangular space decompression with or without selective medial triceps to axillary end-to-side nerve transfers is associated with improvement in shoulder abduction strength, pain, and DASH scores in patients with incomplete axillary nerve palsy.

Unusual Vascular Distribution in the Third Segment of the Axillary Artery

The third segment of the axillary artery (TSAA) is the main vascular supply to the muscles of the upper limb. Numerous studies have reported atypical branching patterns of the TSAA, which can complicate operative interventions involving structures supplied by this segment of the artery. Our current study evaluated a previously undescribed branching pattern in the TSAA, in which the subscapular artery gave rise to an unusual posterior humeral circumflex artery, and a second subscapular artery. In addition, a third variant was found in the origin of the thoracodorsal artery: two collateral horizontal arteries supplying the deep medial surface of the latissimus dorsi muscle. Vascular anatomical variants may affect the classical upper limb interventions requiring modification of the traditional surgical approaches. This case report aims to evaluate these variants from a clinical perspective regarding the management of upper limb trauma, axillary, breast, and muscle flap surgery.

Unusual Origin of the Posterior Circumflex Humeral Artery: A Case Report

Prior knowledge of possible variations in human anatomy is essential for basic medical and clinical training. Many surgeons can avoid uncharacteristic situations by having sources and availability of resources that document potential irregularities in human anatomy. In this case, a human cadaver is identified as having an altered origin of the posterior circumflex humeral artery (PCHA). While it usually stems from the axillary artery, this cadaver had a left-sided PCHA originating from the subscapular artery (SSA) and continuing into the quadrangular space. This irregularity of the PCHA from the SSA is not commonly discussed in the literature. Physicians and anatomists need to be fully aware of this possibility and be prepared for any unexpected differences in anatomy during procedures.

Quadrilateral space syndrome

The quadrilateral space is a confined area through which the axillary nerve and posterior circumflex humeral artery (PCHA) travel in the shoulder. Both structures are susceptible to impingement and compression as they travel though this space resulting in a constellation of symptoms known as quadrilateral space syndrome (QSS). Patients may experience paresthesias, loss of motor function, pain and vascular complications. Individuals who perform repetitive overhead arm movements such as elite athletes are at greater risk of developing QSS. The diagnosis can be difficult, but in the setting of clinical suspicion, physical exam and imaging studies can provide specific findings. On MRI, patients may have atrophy of the deltoid or teres minor muscles and angiography may show aneurysm or vascular occlusion of the PCHA. Treatment is initially conservative, with physiotherapy. Surgical decompression is effective in patients with severe or progressive symptoms. Causes of external compression such as fibrous bands, scarring, or other space occupying lesion may be addressed at that time. Neurolysis and aneurysm resection may also be performed. In some cases, emboli from the PCHA can cause ischemia in the involved upper extremity resulting in an acute presentation. Catheter directed therapy such as thrombolysis or thrombectomy may performed emergently in these cases. Though rare, in patients presenting with arm weakness, paresthesia, pain and/or arterial thrombosis in the arm, QSS is an important entity to consider.

Unknown variant of the accessory subscapularis muscle?

Acting in medial rotation of the arm, the subscapularis (SM) is the most powerful and largest muscle of the rotator cuff. It is morphologically variable, especially in the number of tendons, place of insertion, and number of bellies, and it is sometimes fused with another muscle. An accessory subscapularis muscle (ASM) is among the morphological variations of the SM, but it is a really rare variant. The present case describes a very rare ASM that is divided into proximal tendinous attachment, intermediate fleshy muscular belly and distal tendinous attachment. Its origin is located on the lateral border of the scapula, but some fibers are connected with the muscular part of the SM. Its distal attachment is fused with the capsule of shoulder joint, above the tendinous insertion of the SM. Such an arrangement allows for greater stabilization of the joint. Moreover, there is a possibility that it could be used during treatment of ruptured SM tendons.

Clinico-radiological review of peripheral entrapment neuropathies - Part 1 upper limb

PURPOSE

This article aims to review the pertinent anatomy, etiopathogenesis, current clinical and radiological concepts and principles of management in case of upper limb entrapment neuropathies.

METHODS

The review is based on critical analysis of the existing literature as well as our experience in dealing with entrapment neuropathies.

RESULTS

Entrapment neuropathies of the upper limb peripheral nerves are common conditions that are often misdiagnosed because of their varying clinical presentations and lack of standardized diagnostic methods. Clinical assessment and electrodiagnostic studies have been the mainstay; however, imaging techniques have provided newer insights into the pathophysiology of these entities, leading to a paradigm shift in their diagnosis and management. The current best practice protocols for entrapment syndromes are constantly evolving with increasing emphasis on the role high-resolution ultrasound and magnetic resonance imaging. Many imaging criteria are described and we have tried to present the most validated measurements for diagnosing entrapment neuropathies.

CONCLUSION

It is imperative for a clinical radiologist to be familiar with the etiopathogenesis and clinical features of these conditions, in addition to being thorough with the anatomy and the latest imaging strategies.

Neuralgic amyotrophy: a paradigm shift in diagnosis and treatment

Neuralgic amyotrophy (NA), also known as Parsonage-Turner syndrome, is characterised by sudden pain attacks, followed by patchy muscle paresis in the upper extremity. Recent reports have shown that incidence is much higher than previously assumed and that the majority of patients never achieve full recovery. Traditionally, the diagnosis was mainly based on clinical observations and treatment options were confined to application of corticosteroids and symptomatic management, without proven positive effects on long-term outcomes. These views, however, have been challenged in the last years. Improved imaging methods in MRI and high-resolution ultrasound have led to the identification of structural peripheral nerve pathologies in NA, most notably hourglass-like constrictions. These pathognomonic findings have paved the way for more accurate diagnosis through high-resolution imaging. Furthermore, surgery has shown to improve clinical outcomes in such cases, indicating the viability of peripheral nerve surgery as a valuable treatment option in NA. In this review, we present an update on the current knowledge on this disease, including pathophysiology and clinical presentation, moving on to diagnostic and treatment paradigms with a focus on recent radiological findings and surgical reports. Finally, we present a surgical treatment algorithm to support clinical decision making, with the aim to encourage translation into day-to-day practice.

A very rare case of an accessory subscapularis muscle and its potential clinical significance

The subscapularis muscle is the largest muscle of the rotator cuff and its main function is internal rotation. It is morphologically variable in both point of origin and insertion. The presence of an accessory subscapularis muscle can lead to brachial plexus neuropathy. This report presents a very rare accessory subscapularis muscle originating from two distinct bands on the subscapularis and teres major muscles. The insertion was divided among four tendons. The fourth tendon is bifurcated. One of these was connected to the tendon of the subscapularis muscle and the other three inserted into the base of the coracoid process of the scapula. This anomalous muscle has the potential to entrap the nerves of the posterior cord such as the axillary, lower subscapular, and thoracodorsal nerves.

Teres minor and quadrilateral space syndrome: A review

The teres minor is one of four rotator cuff muscles that is involved in many shoulder pathologies. The integrity of the teres minor can be indicative of treatment success for disorders including rotator cuff tears, impingement syndrome, and quadrangular space syndrome. Quadrangular or quadrilateral space syndrome is a debilitating disorder that may require surgical intervention in chronic cases and can lead to atrophy of the teres minor. A review of the diagnostic techniques and treatment methods for disorders involving teres minor, with a focus on quadrilateral space syndrome, are presented in order to summarize the current understanding of these pathologies.

Diagnosis of hypothenar hammer syndrome in a patient with acute ulnar artery occlusion

A 56-year-old truck driver with a history of tobacco use presented with acute onset digital ischaemia in the ulnar distribution of his dominant hand, associated with severe pain. Occupational exposures included extensive manual labour and prolonged vibratory stimuli. Workup with Doppler and angiography confirmed the diagnosis of hypothenar hammer syndrome (HHS). After the failure of medical management, he underwent ulnar artery thrombectomy with reconstruction and arterial bypass grafting. His pain improved significantly postsurgically, and he was able to return to a normal routine. This case illustrates the classic presentation, examination, imaging findings and management options of HHS. HHS should be considered in patients with digital ischaemia and associated occupational exposures. Diagnosing the condition appropriately allows for optimal management, aiming at minimising symptoms and maximising quality of life.

Fluoroscopic-guided quadrilateral space block for the treatment of quadrilateral space syndrome - A case report

We report a case of a 48-year-old female who presented four months following a low-energy trauma with symptoms most consistent with adhesive capsulitis. An MRI demonstrated extensive patchy areas of intramuscular edema-like signal involving the lateral head of the deltoid with associated muscle atrophy, in keeping with a subacute denervation injury. She was diagnosed with quadrilateral space syndrome (QSS) and successfully treated with an fluoroscopic-guided corticosteroid injection. At her two-year follow-up, the patient had regained full function and had no lasting symptoms. Non-specific symptoms like ill-defined shoulder pain, decreased motor function, and weakness can delay the diagnosis and management of QSS. As there is a lack of a good diagnostic study, fluoroscopic-guided quadrilateral space block should be considered should the diagnosis fit a patient's clinical profile, as this has the potential to be both diagnostic and therapeutic.