Conservative treatment for Carpal Tunnel Syndrome caused by persistent median artery: a case report

Knowledge of a persistent median artery, defined as an anatomical vascular variation, is of clinical importance because it can be an unusual etiology of carpal tunnel syndrome. This report describes the case of a 42-year-old female patient with acute pain and paresthesia involving the volar aspect of the first, second, and third fingers of the left hand. The clinical manifestations pointed to compressive neuropathy of the median nerve, and diagnostic imaging showed anatomical vascular variation. Details were collected through interviews with the patient, and photographic records of imaging exams were thoroughly analyzed. This case study shows the importance of the identification and knowledge about anatomical variations considering that under specific pathological conditions, they can be a cause of clinical syndromes. Such knowledge is also important in the field of surgery for the prevention of iatrogenic injuries.


Introduction
The median artery is a transient vessel that develops from the axial artery of the upper limb at the beginning of embryonic life (Alexander, Leal, & Baptista, 2020). It follows the median nerve and can be a part of the structure of the superficial palmar arch. It is responsible for the blood supply of the hand in embryos (Haładaj, Wysiadecki, Dudkiewicz, Polguj, & Topol, 2019). With the development of the radial and ulnar axial arteries, the median artery regresses and disappears during the post-fetal phase (Aragão, da Silva, Anunciação & Reis, 2017).
A persistent median artery (PMA) is a rare anomaly (Aragão, da Silva, Anunciação & Reis, 2017;Srivastava, Sharma, & Pillay, 2015). It is an anatomical variation, which is defined as an embryonic vestige, and appears as a satellite vessel of the median nerve (Chim, 2016). The artery traverses the anterior aspect of the forearm, and in the distal region of this segment, it accompanies the flexor muscle tendons as contents of the carpal tunnel (Jain et al., 2020).
The origin and evolution of the median artery are variable, and it can arise from the radial artery, the ulnar artery, or more commonly, the anterior interosseous artery (Jain et al., 2020). The median artery is the dominant vessel for blood supply in the embryonic hand. When it has an increased caliber (> 3 mm) in the presence of some pathological conditions including internal thrombus, aneurysm, and the formation of calcified plaques, it becomes an independent risk factor for carpal tunnel syndrome (CTS) (Chen, Chen, Hu, & Jiang, 2017;Feintisch, Ayyala, & Datiashvili, 2017). CTS is one of the most common pathologies of the hands (Wright & Atkinson, 2019) and is characterized by compression of the median nerve in the wrist, causing pain, paresthesia, numbness, and weakness in the hand (Ono, Clapham, & Chung, 2010;Wang, Buterbaugh, Kadow, Goitz, & Fowler, 2018). This case report describes an unusual etiology of CTS and highlights magnetic resonance imaging as a diagnostic method to assist in the recognition of anatomical variations and conservative treatment as an alternative to surgical procedures.

Methodology
This study presents a case report that according to Yin (2015); Pereira et al. (2018) and Ludke and Andre (2013) is a methodology that focuses on a rare specific case and in which the phenomenon under study is detailed. This is a qualitative study in which the patient sought private care to relieve pain in the region of the left wrist and hand, associated with a tingling sensation mainly affecting the fingertips. After the diagnosis of the rare case and after successful conservative treatment, the patient's case was reported. To this end, the patient signed a Free and Informed Consent Form. All procedures performed in this study adhered to ethical standards. This case was approved by the University of Vassouras Research Ethics Committee, Vassouras, Brazil (process number 4.670.438).

Case Description
A 42-year-old female patient complained of sudden onset of severe pain (visual analog scale score, 8) involving the region of the left wrist and hand, associated with a tingling sensation mainly affecting the fingertips. After the onset of pain symptoms, the patient used oral analgesics (Novalgine, 1g, 12/12 hours) and non-hormonal anti-inflammatory drugs (Nimesulide, 100 mg, 8/8 hours) continuously for 10 days. After 10 days following medical protocols, she sought medical care Research, Society and Development, v. 10, n. 12, e483101220884, 2021 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v10i12.20884 3 because of persistent pain. There was no correlation between the onset of symptoms and movements or repetitive actions. She had no comorbidities and denied alcoholism and smoking. There was no history of local trauma or surgery; rheumatological, oncological, or thyroid diseases; or muscle weakness.
The Phalen and Tinel tests showed positive results. The patient was instructed to maintain the use of oral analgesic medications, undergo cryotherapy, rest the joint, and undergo immobilization with an orthosis for a minimum period of 45 days. Stretching of the wrist, hand, and fingers was also performed according to medical guidelines. Ultrasound examination of the left wrist was requested due to a suspicion of compression syndrome of the median nerve at the level of the carpal tunnel.
Ultrasound examination without Doppler analysis of the left wrist showed enlargement of the median nerve, and a tubular structure between the nerve was identified, raising the possibility of an anatomical vascular variation. As there was no improvement in pain 30 days after treatment, magnetic resonance imaging of the left wrist was performed, which confirmed the presence of a PMA, with signs of thrombosis (Figure1). New treatment was performed using injectable Diprospan, with a dose of 2 ml via deep intramuscular injection in a single dose, leading to a satisfactory improvement in the initial clinical condition (pain and paresthesia) in 15 days.
Conservative treatment was concluded after 2 months, with adequate patient satisfaction and complete resolution of clinical symptoms; there was no need for surgical treatment for the decompression of the median nerve and the thrombotic event. The patient remains asymptomatic, with no recurrence of pain. The evolution of the treatment is shown in Figure 2.

Discussion
Inflammatory changes in the tendons, nerves, and joint compartments, which are frequent causes of CTS, were ruled out. Thus, magnetic resonance imaging of the left wrist was requested, which surprisingly showed a PMA complicated with vascular thrombosis, establishing the etiology of CTS. A PMA with thrombosis causing CTS is uncommon (Jain et al., 2020).
Current studies have indicated that magnetic resonance imaging is an important auxiliary tool for identifying unusual causes of CTS (Chen, Chen, Hu, & Jiang, 2017) and can be used to detect rare pathological causes of CTS (Jeon, Lee, & Yang, 2020); this is important for differential diagnosis in cases involving ambiguous symptoms (Ibrahim, Khan, Goddard, & Smitham, 2012). Magnetic resonance imaging has already been used for diagnosing thrombosis of a PMA with subsequent development of acute CTS (Vag, Koch, Waldt, & Wörtler, 2012).
The existence of this vascular variant can contribute to varying complications, such as the pronator teres syndrome, compression of the median nerve, and compression of the anterior interosseous nerve (Potu et al., 2011). Recognizing anatomical variations in the arterial supply of the hand, including those of the superficial palmar arch, is necessary for performing safe and successful surgical procedures in the wrist and hand (Chim, 2016).
The reported case involved a vascular anatomical variation that presented as an unusual etiology of CTS; such variations are not always recognized but can play an important role in the appearance of clinical symptoms of a common pain syndrome in medical practice. usually, CTS is diagnosed based on clinical history and physical examination findings (wang, buterbaugh, kadow, goitz, & fowler, 2018). However, in some cases, there is a need for diagnostic imaging methods for ensuring correct treatment and reduction of morbidity being able to solve the problem without the need for surgery.

Conclusion
In conclusion, PMA is an unusual etiology that can cause CTS. Magnetic resonance imaging is an important image exam for the recognition of this anatomical variation. The recognition of PMA is important to avoid misdiagnosis and delays in treatment and conservative treatment can be performed as an alternative with positive results in some cases.
Although the treatment offered to the patient had been successful, future research with a larger sample is important to assess whether conservative treatment will keep other asymptomatic patients without pain