Preliminary experiences in diagnosing and treating neuralgic amyotrophy with ulnar nerve involvement often misdiagnosed as cubital tunnel syndrome

Abstract

Background

Neuralgic amyotrophy (NA) involving the ulnar nerve is frequently misdiagnosed as cubital tunnel syndrome (CuTS), leading to delayed or inappropriate treatment. This study reports aims to share our initial experiences in diagnosing and managing this underrecognized condition, highlighting the key clinical insights to improve differential diagnosis and therapeutic strategies.

Methods

A retrospective analysis was conducted on 25 participants (30 limbs) diagnosed with NA affecting the ulnar nerve between October 2016 and June 2022. Among these patients, 20 had unilateral involvement and 5 had bilateral involvement. Individualized treatment plans, including conservative management and surgical decompression, were tailored based on disease severity and patient response. Clinical outcomes were assessed using the visual analog scale (VAS), static two-point discrimination (2PD) test, and Disabilities of the Arm, Shoulder, and Hand (DASH) Questionnaire scores over a follow-up period of 6 to 14 months.

Results

All patients exhibited pain, numbness, or weakness in the region innervated by the ulnar nerve. Conservative treatment was successful in 5 participants (6 limbs) with early-stage mild disease, while 20 participants (24 limbs) underwent surgical decompression after conservative therapy failed. At final follow-up, 22 participants (26 limbs) demonstrated improvement in DASH scores. However, 3 limbs retained VAS scores above 3 points, with no significant recovery according to the static 2PD test. Additionally, 3 participants (4 limbs) exhibited poor postoperative functional recovery after 1 year.

Conclusions

NA involving the ulnar nerve is often misinterpreted as CuTS, complicating diagnosis and management. A thorough review of patient history, combined with electromyographic (EMG) and ultrasound evaluations, is crucial for accurate diagnosis. Patients with early-stage NA may respond well to conservative therapy, but advanced cases should be counseled on the potential limitations of surgical outcomes. Our findings emphasize the necessity of prompt, accurate diagnosis and personalized treatment to optimize patient recovery.

Introduction

Neuralgic amyotrophy (NA) is a peripheral nerve disorder characterized by sudden limb pain, rapid weakness, and muscle atrophy (1). It primarily affects the posterior interosseous, anterior interosseous, radial, axillary, and suprascapular nerves (2). Distinguishing NA from cervical spondylosis and peripheral nerve compression is crucial. Historically, NA has been considered rare, with an incidence of 1:100,000. However, recent studies, such as van Alfen et al.’s, suggest that the actual incidence rate is 1:1,000 or higher (3).

NA has long been deemed a condition with an inherent propensity for spontaneous resolution. Nevertheless, emerging research disputes this traditional view (1-3). Some experts advocate for a minimum 3-month observation period after symptom onset to permit any potential spontaneous nerve regeneration. Throughout this interim, conservative treatment, such as corticosteroid administration, immunotherapeutic interventions, and pain alleviation measures, are deemed appropriate, especially during the acute phase. Should symptoms remain unimproved beyond this timeframe, surgical intervention may be considered. The ultrasound images of NA include swelling, incomplete constriction, complete constriction, and torsion structural changes in the affected nerves (4). Gstoettner et al. (5) reported that the decision for should be made based on the degree of constriction, with assessed nerve or fascicle thinning classified as follows: mild, <25% thinning; moderate, 25–75% thinning; and severe, >75% thinning. In cases of complete constriction, Gstoettner et al. do not advise interfascicular neurolysis, and instead favor neurorrhaphy. Others suggest that once complete denervation is found on neurophysiological examination, surgery should be immediately applied (6). In all cases, early diagnosis is critical.

Cubital tunnel syndrome (CuTS) can arise due to factors that affect the cubital tunnel’s structure, such as nerve compression, stretching, or friction (7). Its main symptoms include numbness or paresthesia on the ulnar side of the hand and potential atrophy of the abductor digiti minimi muscle and first dorsal interosseous muscle. Electromyographic (EMG) tests may detect a notable decrease in nerve conduction velocity (NCV) along the ulnar nerve at the elbow, indicating an evident nerve conduction block. Some patients with NA affecting the ulnar nerve may experience muscle atrophy, tingling, or numbness in the ring and little fingers, which can be mistakenly diagnosed as CuTS.

Nevertheless, there are few reports on NA with ulnar nerve involvement. In this paper, we describe a series of patients with NA and a retrospective analysis of the diagnostic and treatment processes of NA involving the ulnar nerve susceptible to misdiagnosis as CuTS. We further discuss the factors that may influence treatment effects to reduce misdiagnoses by clinicians and provided preliminary insights into the diagnosis and treatment of NA involving the ulnar nerve. We present this article in accordance with the STROBE reporting checklist (available at https://qims.amegroups.com/article/view/10.21037/qims-2024-2477/rc).

Methods

The data of 25 study participants (30 limbs) admitted to Ningbo No. 6 Hospital in Zhejiang, China between October 2016 and June 2022 were retrospectively analyzed. The initial EMG findings in patients with atypical symptoms suggested CuTS. However, a joint consultation with neurology and hand surgery specialists ultimately led to a diagnosis of NA-induced ulnar neuropathy. This study received approval from the ethics committee of Ningbo No. 6 Hospital [No. 2022-014(K)] and was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. All participants provided written informed consent before participation.

The diagnostic criteria for NA with ulnar nerve involvement including the following: acute onset; numbness in the ulnar aspect of the ring finger and the little finger; dysesthesia or pain; muscle atrophy or weakness in the hand; hypothenar atrophy; positive Tinel sign or elbow flexion test; and fulfillment of the diagnostic criteria for NA proposed by van Alfen et al. (3) in 2015, including new onset pain, with a score more than 7 on a scale of 0–10; less severe initial pain with otherwise typical clinical multifocal distribution of weakness and monophasic course; and more extensive multifocal paresis of upper extremity.

The inclusion criteria for patients were as follows: (I) fulfillment of the clinical diagnostic criteria for NA; (II) Doppler ultrasound or magnetic resonance imaging revealing edema, thickening, or constriction in various segments of the ulnar nerve; and (III) EMG findings indicating absent nerve action potentials in the intrinsic hand muscles and a reduction in NCV along the ulnar nerve at the elbow.

Meanwhile, the exclusion criteria were (I) a history of elbow joint surgery; (II) CuTS; and (III) individuals who did not cooperate with follow-up protocol and failed to complete clinical assessments.

In this study, 25 participants (30 limbs) were enrolled. The participants comprised 18 men and 7 women aged between 23 and 62 years (43.3±12.3 years). Of these, 20 participants were affected unilaterally and 5 were affected bilaterally. All participants exhibited functional impairment symptoms, including pain, numbness, or weakness in areas innervated by the ulnar nerve. Disease onset was determined based on the time of ulnar nerve symptom appearance. Treatment protocols, whether conservative or surgical, were tailored to individual clinical features, disease severity, and duration. During surgery, the intraoperative findings of participants who underwent the procedure were compared with the corresponding preoperative ultrasound examination results to confirm the diagnosis.

Treatments

Conservative treatment

Study participants with short disease duration (time from disease onset to hospitalization less than 1 month) and mild symptoms were administered immunity-boosting and nerve-nourishing treatment and corticotherapy. Human immunoglobulins for intravenous injection (2.5 g/day for 1 week) were used to boost immunity. Patients were suggested to take oral prednisolone 40 mg per day for 10 days and 10 mg per day for another 10 days. If the patient had other accompanying symptoms, symptomatic treatment was administered.

Surgical treatment

Surgery was performed on study participants for whom 1 to 3 months of conservative treatment proved to be ineffective, as well as on those with disease duration of more than 6 months or with associated obvious atrophy of the intrinsic hand muscles with a failure of conservative treatment.

In situ ulnar nerve decompression

For in situ ulnar nerve decompression, a 5-cm incision was made along the medial side of the elbow. The medial cutaneous nerve and muscular branches of the ulnar nerve were protected, and the arcuate ligament between the 2 heads of the flexor carpi ulnaris muscle was dissected at the distal end. During the surgery, the arcade of Struthers was released at the proximal end, and the deep fascia around the nerve was completely released. Intraoperatively, passive flexion and extension movements of the elbow joint were performed to ensure ulnar nerve subluxation. Postoperatively, the operated limb was immobilized for 1 week.

Decompression and anterior transposition of the ulnar nerve

In patients exhibiting severe nerve damage accompanied by conditions such as osteoarthritis or anatomical abnormalities of the elbow joint, a 12-cm-long longitudinal incision was created above and below the elbow. Consequently, the ulnar nerve was fully decompressed, and the medial intermuscular septum was detached. The ulnar nerve was transposed anteriorly underneath the deep fascial flap. Postoperatively, the limb was immobilized for 3 weeks.

For patients exhibiting ultrasound pathological changes in the ulnar nerve at the wrist, Guyon’s canal decompression is recommended. In order to expose the ulnar nerve’s deep branch, surgeons made an incision in the intrinsic tendinous arch of the hypothenar muscles, allowing for the release of the epineurium.

Pre- and posttreatment clinical assessment

All participants underwent outpatient follow-up for a duration of 6 to14 months. Symptoms including pain, numbness, and weakness were recorded. Before surgery and during outpatient follow-up, all participants completed the visual analog scale (VAS), static two-point discrimination (2PD) test, and Disabilities of the Arm, Shoulder, and Hand (DASH) Questionnaire.

Statistical analysis

Data were statistically analyzed with SPSS 20.0 (IBM Corp., Armonk, NY, USA). Data normality was assessed via the Kolmogorov-Smirnov test. Comparison of pretreatment and posttreatment VAS, 2PD test, and DASH scores was conducted via the t-test. Statistical significance was set at P<0.05.

Results

All 25 participants (30 limbs) experienced pain, numbness, or weakness. The time span from the onset of symptoms to hospital admission varied, ranging from 2 weeks to 14 months. On average, this duration was approximately 4 [interquartile range (IQR), 2–6.25] months. Among the patients, 1 (1 limb) did not report for follow-up, while all the other participants reported for outpatient follow-up for 8 (IQR, 6–11) months. Moreover, clear interosseous muscle atrophy was observed in 20 participants (24 limbs). Furthermore, there was significant pain in 15 limbs, numbness in the ring and little fingers in 16 limbs, isolated muscle atrophy with impaired finger adduction in 18 limbs, and concurrent involvement of other nerves in 6 participants. Ultrasound examination results showed diffuse edema and thickening of the ulnar nerve at the elbow and forearm in all 30 affected limbs. Additionally, swelling of the ulnar nerve in Guyon’s canal was observed in 8 participants (11 limbs).

Conservative treatment helped alleviate symptoms in 5 participants (6 limbs) who had mild early-stage disease. A total of 20 participants (24 limbs) underwent surgical decompression of the ulnar nerve. Intraoperative observations revealed edema, thickening, or ground glass-like changes in various segments of the ulnar nerve.

At the final follow-up, 15 participants (18 limbs) had achieved complete recovery, while 3 (4 limbs) failed to show significant alleviation. Among the remaining 7 participants (8 limbs), some experienced persistent symptoms. Specifically, long-term pain persisted in 3 limbs, numbness persisted in the pulp of the little finger in 3 limbs, and weakness in finger abduction and adduction persisted in 5 limbs.

The pretreatment and posttreatment scores, respectively, were 4 (IQR, 1, 4.5) and 0 (IQR, 0, 1) points for VAS, 6 (IQR, 4, 8) and 4 (IQR, 4, 8) mm for the static 2PD test, and 31 (IQR, 24, 38.5) and 12 (IQR, 8, 16) for the DASH questionnaire (see Table 1).

Table 1. Comparison of VAS, 2PD test, and DASH questionnaire scores of patients with NA and ulnar nerve involvement before treatment and at the final follow-up.

Time	Before treatment	Final follow-up	P
VAS	4 (1, 4.5)	0 (0, 1)	<0.0001
2PD	6 (4, 8)	4 (4, 8)	<0.0001
DASH	31 (24, 38.5)	12 (8, 16)	<0.0001

Data are presented as median (IQR). 2PD, two-point discrimination; DASH, Disabilities of the Arm, Shoulder, and Hand; IQR, interquartile range; NA, neuralgic amyotrophy; VAS, visual analogue scale.

Typical cases

Patient 1

A 24-year-old male patient complained of numbness and weakness in the left ring and little fingers that had lasted for over 3 months. The patient had a history of an upper respiratory tract infection 3 months prior. During the physical examination, atrophy of the first dorsal interosseous muscle (++) was observed. Moreover, there was mild claw hand deformity in the ring and little fingers, limited finger abduction and adduction activity (Figure 1A), and a significant decline in grip strength. Before the surgery, EMG revealed a decrease in conduction velocity and a reduction in the amplitude of the ulnar nerve. Ultrasound examination indicated that the left forearm ulnar nerve was more significantly enlarged in multiple segments as compared to the right side, leading us to consider NA. Additionally, clear edema changes were observed in multiple segments of the ulnar nerve during surgery. The left cubital tunnel and Guyon’s canal were subsequently surgically released. Nerve exploration was also conducted on the ulnar nerve in the forearm (Figure 1B-1D). Eleven months after surgery, the patient exhibited significant improvement in grip strength in the left hand. There was no numbness in the fingers, and finger abduction and adduction activity was satisfactory (Figure 1E,1F).

Figure 1.

Clinical presentation and surgical exploration of a 24-year-old male patient with ulnar nerve entrapment neuropathy. (A) Significant atrophy of the first dorsal interosseous muscle (++), along with mild claw hand deformity in the ring and little fingers and a notable decline in grip strength. (B-D) The left cubital tunnel and Guyon’s canal were subsequently released, and nerve exploration was also conducted on the ulnar nerve in the forearm. (E,F) Eleven months after surgery, the patient exhibited a clear improvement in grip strength of the left hand, absence of numbness in the fingers, and satisfactory finger abduction and adduction activity.

Patient 2

A 23-year-old male patient was hospitalized due to numbness and weakness in the bilateral ring and little fingers for more than 2 months. He had no obvious infectious or trauma. Physical examination revealed atrophy of the first dorsal interosseous muscle (+), mild claw hand deformity (more pronounced in the dominant right hand), limitation of finger abduction and adduction activity, and a significant decline in grip strength of both hands (more pronounced in the right hand) (Figure 2A-2C). EGM revealed axonal injury as the primary manifestation and absent nerve action potentials. Ultrasound examination detected thickening and hypoechoic area in the right ulnar nerve at the elbow region. We thus considered NA. During the intraoperative assessment, nerve edema and ground glass-like changes were observed in the ulnar nerve at the same elbow region. The left cubital tunnel and Guyon’s canal were subsequently released surgically, and nerve decompression was performed on the ulnar nerve in the forearm (Figure 2D). Subsequently, 3 months after operation, mild flexion was noted in the right little finger (Figure 2E, left), and 8 months after operation, the patient reported an absence of numbness in the fingers of both hands, satisfactory finger abduction and adduction activities, and a significant improvement in the claw hand deformity in the ring and little fingers, leading to a full restoration of normal hand function (Figure 2E, right). A linear scar was reported in the right elbow (Figure 2F).

Figure 2.

Clinical presentation, surgical management, and postoperative recovery of a 23-year-old male patient with ulnar nerve injury. (A-C) First dorsal interosseous muscle atrophy (+), mild claw hand deformity (more pronounced in the dominant right hand), limitation of finger abduction and adduction activity, and a significant decline in grip strength of both hands. (D) Nerve edema and ground glass-like changes in the ulnar nerve at the right-side elbow were discovered intraoperatively. (E) (left) three months after operation, mild flexion was observed in the right little finger; (right) 8 months after operation, the patient reported absence of numbness in the fingers of both hands, satisfactory finger abduction and adduction activity, and resolution of claw hand deformity in the ring and little fingers. (F) The presence of a linear scar on the right elbow was observed.

Stereoscopic images of the ulnar nerve, reconstructed from ultrasonic sound data, revealed bilateral ulnar nerve thickening in multiple segments at the elbow, forearm, and wrist (indicated by arrows in Figure 3A). The right-side ulnar nerve revealed considerable enlargements from the nerve cross-sectional area in different places (Figure 3B). The maximum ratio of the cross-sectional area of the forearm on the same horizontal level was 1.84 (Figure 3C).

Figure 3.

Preoperative ultrasound examination data for patient 1. (A) Bilateral ulnar nerves showed thickening (indicated by arrows) in multiple segments at the elbow, forearm, and wrist. (B,C) Notable enlargement of the nerve cross-sectional area. The dashed line “c” represents the plane of the medial epicondyle of the humerus, the largest CSASR. CSA, cross-sectional area; CSASR, cross-sectional area to stroke ratio.

Patient 3

A 56-year-old male patient had a chief complaint of numbness and pain associated with weakness in the left ring and little fingers for 2 weeks. Physical examination revealed muscle atrophy in the first dorsal interosseous muscle (+) and limitation of the abduction and adduction activity in the ring and little fingers (Figure 4A,4B), while ultrasound examination revealed visible nerve swelling at the left elbow. The patient was administered oral prednisolone 40 mg per day for 10 days and 10 mg per day for another 10 days. Six months later, satisfactory abduction and adduction activity in the left ring and little fingers was observed (Figure 4C,4D), with residual mild pain at the fingertips.

Figure 4.

Clinical presentation, treatment, and recovery of a 56-year-old male patient with left ulnar nerve injury following vaccination. (A,B) First dorsal interosseous muscle atrophy (+) and limitation of the abduction and adduction activity of the ring and little fingers. (C,D) Six months after oral prednisolone administration, there was altered satisfactory abduction and adduction activity in the left ring and little fingers, with residual mild pain at the fingertips.

Discussion

NA is characterized as an acute, monophasic, focal or multifocal inflammatory neuropathy that may involve any part of the brachial plexus (5). In clinical practice, the manifestations of NA involving the ulnar nerve are difficult to distinguish from those of CuTS. In this study, the clinical presentations and auxiliary examination characteristics of 25 participants (30 limbs) with NA involving the ulnar nerve were retrospectively analyzed. Differential diagnoses were established for these participants, followed by the administration of surgical or conservative treatments, both of which resulted in favorable outcomes.

Pan et al. reported the presence of hourglass-like changes in patients with a confirmed diagnosis of NA (8). However, there is limited mention in the literature regarding the occurrence of ulnar nerve involvement or the presence of hourglass-like changes in these patients.

Misdiagnosis of NA with ulnar nerve involvement as CuTS

EMG is widely recognized as the gold standard for diagnosing peripheral nerve entrapment (2). However, exclusive reliance on EMG examinations can potentially lead to diagnostic errors. The EMG findings of CuTS typically show absent nerve action potentials in the first dorsal interosseous muscle and fibrillation in the target muscles. As demonstrated in Table 2, the symptoms of the patient with NA involving the ulnar nerve are similar to those of patients with CuTS. NA affecting the ulnar nerve is marked by rapid onset, acute pain, muscle atrophy within a short period of time, and early-stage axonal injury. Normal nerve conduction maybe present, and other nerves can also be involved. EMG findings play a crucial role in differential diagnosis.

Table 2. Distinguishing features between NA with ulnar nerve involvement and CuTS.

Feature	NA with ulnar nerve involvement	CuTS
Disease duration	Acute pain	Gradual onset
Muscle atrophy	Occurs within a short period of time	Usually occurs in the advanced stage of the disease
Paresthesia	Not always accompanied by paresthesia	Primarily characterized by paresthesia
Doppler ultrasound	Long-segment, multifocal swelling of the ulnar nerve	Ulnar nerve compression limited to the elbow
EMG	Axonal injury is the primary manifestation during the early stage; absent nerve action potentials can be observed; multiple nerves may be involved during the early stage	Reduced sensory and motor conduction velocities of the ulnar nerve; absent nerve action potentials found in the late stage

CuTS, cubital tunnel syndrome; EMG, electromyographic; NA, neuralgic amyotrophy.

Clinical value of ultrasound in the diagnosis of NA

Arányi et al. reported several types of structural changes in the nerves affected by NA in the ultrasound images, including swelling, incomplete constriction, complete constriction, and torsion (4). The various clinical presentations of primary CuTS and NA as seen on ultrasound can provide guidance for surgical treatment. Given the exclusion of other abnormal conditions, the differential diagnosis of CuTS requires the incorporation of ultrasound examinations, which can provide clear imaging of the muscle innervations (9,10). Ultrasound images of patients with primary CuTS typically reveal nerve entrapment and narrowing at the cubital tunnel, along with swelling in the proximal nerve segment. In contrast, patients with NA often exhibit long-segment edema affecting multiple segments of the nerve (11,12). In this study, the preoperative ultrasound examination results of 11 limbs indicated that nerve edema was not restricted to the cubital tunnel but also occurred in the forearm and Guyon’s canal (Table 2). The presence of edema or constriction was also observed in other nerves, which was consistent with the multi-segment involvement that is characteristic of NA. However, hourglass-like constrictions were not detected in the ulnar nerve of all patients, which was consistent with the preoperative Doppler ultrasound findings but different from the findings from other NA-affected nerves. It was discovered that patients with NA with associated ulnar nerve involvement were more likely to develop concomitant nerve lesions in Guyon’s canal, thereby inducing secondary entrapment, consistent with the characteristics of CuTS. Ultrasound examination results from 8 participants (11 limbs) indicated ulnar nerve thickening in the ulnar aspect of the wrist, prompting the intraoperative opening of Guyon’s canal for decompression. Electrophysiological testing often cannot accurately identify simultaneous ulnar nerve entrapments in the region of the elbow and Guyon’s canal. In these cases, cubital tunnel nerve release alone may not effectively alleviate the symptoms.

Association of prognosis with disease severity and duration

van Alfen et al. reported that 80% of patients with NA can recover spontaneously. Nevertheless, the recovery time may vary from several months to several years, and many patients will still experience residual pain, leading to reduced movement tolerance in the affected limb (13). According to Van Eijk et al., pharmacological treatment with immunoglobulins and corticosteroids during the early stage of NA may help alleviate pain or assist in functional recovery (14). In our study, patients who were administered oral prednisolone treatment for 2 weeks in a timely manner after disease onset experienced a shorter duration of pain symptoms and A quicker recovery. Additionally, 3 participants whose total duration of time from onset of symptoms until hospital admission was less than 3 months underwent conservative treatment. Following oral prednisolone and symptomatic treatment, the symptoms of these patients gradually diminished and disappeared. Giuffre et al. suggested that conservative treatment should be administered for at least 6 months, while Birch recommends between 3 to 6 months (15,16). However, in our clinical practice, patients who underwent more than 1 year of conservative treatment experienced poorer recovery even after subsequent surgical treatment.

In this study, oral treatment with a combination of ganciclovir and prednisone tablets was administered to 2 participants (2 limbs) with associated herpes infection on the affected limbs. One participant had a history of fever and influenza infection and was administered oral treatment with oseltamivir combined with prednisone. Finally, 2 participants (3 limbs) who exhibited no obvious triggering factors were administered prednisone tablets and nerve-nourishing treatment. Poor functional recovery was observed in 3 participants (4 limbs), which might have been associated with older age and a longer disease duration (>1 year) of patients. Wu et al. investigated treatment approaches for 41 patients with posterior interosseous nerve involvement (17). Their conclusion was that surgical treatment proved to be more effective than conservative measures if recovery was not achieved within 3 months.

For patients with NA involving the ulnar nerve, previous experience of Yu et al. suggests that upon the occurrence of obvious muscle atrophy, surgery for nerve decompression should be performed (18). For patients with mild symptoms and slight muscle atrophy, conservative treatment can be considered. In contrast, if conservative treatment does not yield improvement within 1 month, surgical intervention should be pursued. A posttreatment DASH score can be indicative of a marked improvement in symptoms.

In our study, 3 participants (4 limbs) with a long-term disease duration exhibited an improvement in sensory symptoms compared to their preoperative conditions. In spite of this, intrinsic hand muscle atrophy and claw hand deformity in the ring and little fingers did not exhibit significant improvement. It was speculated that for these patients, the opportunity for nerve regeneration might have been lost despite the successful resolution of nerve entrapment through surgery. Among the remaining participants, 15 (18 limbs) achieved complete recovery of normal function, but 7 (8 limbs) still experienced residual mild sensory, pain, or motor impairment.

Nerve swelling or folding, along with repetitive movements near joints, can induce nerve constriction in patients with NA (19). However, hourglass-like constrictions were not observed in the ulnar nerves of all patients in this study, and the presence of hourglass-like changes in the ulnar nerve has not been reported in the related literature. This phenomenon may be attributable to the anatomical features of the ulnar nerve, which undergoes stretching rather than winding or twisting during elbow flexion.

As this study was retrospective nature and had a small sample size, future prospective studies with larger cohorts should be conducted that examine the long-term follow-up of functional recovery in patients.

Conclusions

The clinical symptoms of NA involving the ulnar nerve are similar to those of CuTS, often resulting in diagnostic challenges. Clinical features alone may be unreliable for differential diagnosis. Therefore, a combination of ultrasound and electrophysiological examinations may be necessary to establish a diagnosis. Early conservative treatment of NA provides satisfactory results. However, patients with a prolonged history of NA and severe symptoms should be completely informed of the potential uncertainty associated with the surgical outcomes.

Supplementary

The article’s supplementary files as

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. This study received approval from the Ethics Committee of Ningbo No. 6 Hospital [No. 2022-014(K)]. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. Written informed consent was obtained from all participants.