Quantitative evaluation of upper extremity strength recovery after cervical epidural block: a retrospective study

Abstract

Background

We aimed to evaluate the clinical efficacy of cervical epidural block (CEB) in enhancing upper extremity (UE) muscle strength in patients with cervical disc herniation (CDH).

Methods

Ten patients with CDH underwent a single CEB session. Follow-up assessments were conducted weekly for 2 weeks through outpatient visits. Handgrip strength on the affected side (AHGS) and the interlateral difference in handgrip strength (DHGS) between the affected and unaffected sides were measured using a dynamometer before, immediately after, 1 and 2 weeks after CEB. Neck pain and radiating UE pain were assessed using a visual analog scale (VAS) at baseline and 2 weeks posttreatment.

Results

The median patient age was 46.4 years (range, 35–78 years). The affected disc levels were C5–6 in five patients, C6–7 in three, and C5–6–7 in two. The left side was affected in six patients and the right in four. The mean VAS score for neck pain decreased from 7.2 to 2.9, whereas that for radiating UE pain decreased from 6.3 to 2.8 after treatment. Both the AHGS and DHGS improved significantly compared to the baseline values at all posttreatment times. However, no significant differences were observed among the posttreatment time points. These findings remained consistent even after adjusting for age and sex.

Conclusion

CEB may offer therapeutic benefits by alleviating pain and improving UE muscle weakness in patients with CDH. However, further large-scale prospective studies are required to validate these preliminary results and determine the long-term efficacy of CEB in managing CDH.

Introduction

Cervical disc herniation (CDH) is a common spinal disorder characterized by pain, neuropathy, and neurological deficits such as upper extremity (UE) muscle weakness and sensory disturbances. These symptoms primarily arise from nerve root compression, which leads to significant functional impairment and a marked decline in the patient’s quality of life and overall health. Therefore, accurate diagnosis and effective treatment are essential [1,2].

The treatment options for CDH range from conservative management to surgical intervention. The initial treatment typically includes pharmacological therapies such as nonsteroidal anti-inflammatory drugs and muscle relaxants, in combination with physical therapy [1,3]. Alternative approaches, including acupuncture and cervical traction, may alleviate pain and improve mobility. When conservative measures fail to achieve adequate symptom relief, interventional procedures, such as nerve blocks and facet joint blocks, may be considered. Surgical intervention may be required for patients who are refractory to these measures [1-3]. Cervical epidural block (CEB) has gained considerable attention as a minimally invasive procedure for alleviating pain and promoting functional recovery in patients with CDH [3]. CEB involves injection of corticosteroids and local anesthetics into the epidural space to reduce inflammation and relieve pain, thereby facilitating functional improvement [3,4]. Previous studies have shown that cervical interlaminar and transforaminal epidural steroid injections provide significant pain relief and functional improvements in patients with CDH and radiculopathy [5-9]. CEB is particularly effective in alleviating neck and radicular pain and has increased clinical utilization [3-5].

Although the analgesic effects of CEB are well-established, its effects on recovery of muscle strength remain unclear. Only a few studies have indicated improvements in muscle strength following CEB as assessed by manual muscle testing (MMT) [5,10]. However, as MMT relies on subjective evaluation, it has inherent limitations in accurately quantifying changes in muscle strength. To overcome this limitation, the use of a dynamometer has been proposed as an objective and reliable method for assessing muscle strength. Dynamometers provide quantitative measurements of muscle strength and are widely used in both clinical and research settings. Handgrip strength (HGS), a representative parameter measured using a dynamometer, has been extensively used in occupational therapy and rehabilitation as a surrogate indicator of overall muscle strength [11]. HGS is strongly correlated with the strength of other UE muscle groups and overall physical performance [12,13]. Therefore, the assessment of hand and forearm muscle strength using HGS not only reflects local muscle function but also serves as an indicator of overall muscular strength and functional capacity [13]. Although C5–7 myotomes are not solely responsible for HGS, previous studies have demonstrated a strong correlation between HGS and overall UE muscle strength and function in both neuromuscular and radiculopathy populations. Moreover, the most affected levels in CDH are C5–6 and C6–7, which are directly associated with major motor innervations that contribute to hand and forearm strength [14]. Previous investigations have also demonstrated significant differences in HGS between the affected and unaffected sides in patients with CDH, irrespective of the lesion level, as well as postoperative improvement in HGS following surgical decompression [15-17]. Therefore, the use of HGS as a quantitative surrogate marker to assess motor recovery in patients with CDH undergoing CEB may be physiologically and clinically justified.

This study aimed to evaluate the effects of CEB on muscle strength in patients with CDH. In this pilot study, using a standardized measurement tool (dynamometer), we quantitatively assessed objective changes in muscle strength to provide a comprehensive understanding of the therapeutic effects of CEB, specifically pain relief and muscle strength recovery, in patients with CDH.

Methods

Ethics statement: This study was approved by the Institutional Review Board (IRB) of Daegu Catholic University Medical Center (IRB No: CR-24-013-PRO-001-R), and the requirement for informed consent was waived.

1. Patient selection

This retrospective study included patients diagnosed with CDH who underwent CEB at the Department of Neurosurgery and Department of Anesthesiology and Pain Medicine at the same hospital between March 2023 and September 2025. Data, including age, sex, and characteristics of the CDH lesions, were collected from electronic medical records. The affected side and CDH levels were determined using magnetic resonance imaging.

Pain intensity in the neck and UEs was assessed using a visual analog scale (VAS). The HGS on the affected side (AHGS) and the difference in HGS between the affected and unaffected sides (DHGS) were measured using a dynamometer at baseline, immediately after CEB, and 1 and 2 weeks after CEB. Patients who did not undergo HGS assessment using dynamometry or who were lost to follow-up within 2 weeks after CEB were excluded. Ultimately, 10 patients were included in this study.

The 2-week follow-up period may have been relatively short. However, several previous studies have shown that motor function recovered 2 weeks after the blockade or that pain was significantly reduced after 1 week. Therefore, we conducted the present study using this timeline [10,18-20].

2. Cervical epidural block

Each patient was positioned prone on the procedural table, with a pillow placed under the chest to elevate the shoulders and induce slight flexion of the cervical spine. This position enabled an optimal needle trajectory during the procedure. After sterile skin preparation and draping, 0.5 to 1 mL of 1% lidocaine was administered subcutaneously at the target site for local anesthesia. An 18-gauge Tuohy needle was inserted into the epidural space at the C6–T1 level via a paramedian approach under fluoroscopic guidance using a C-arm. The initial needle position was confirmed in the contralateral oblique fluoroscopic view to ensure that the needle was located posterior to the spinolaminar line. The needle was subsequently advanced and the ligamentum flavum was punctured using the loss-of-resistance technique to confirm entry into the epidural space. The proper distribution of contrast material throughout the epidural space was verified by confirming the correct positioning of the needle tip in both the anteroposterior and lateral fluoroscopic views. Three milliliters of therapeutic medication, comprising 2 mL of dexamethasone (8 mg) and 1 mL of 2% lidocaine, was slowly injected after accurate needle positioning was confirmed.

3. Outcomes and measures

1) Visual analog scale

VAS is a widely recognized tool for assessing pain intensity in patients with CDH and has demonstrated high validity and reliability across various clinical settings. It consists of a 10-cm horizontal line anchored by descriptors such as “no pain” and “worst imaginable pain,” on which patients indicate a point corresponding to their perceived pain level [21,22]. In this study, VAS scores ranging from 0 to 10 were used to evaluate neck and radicular pain.

2) Handgrip strength

HGS is a widely recognized indicator of overall muscle strength and function, particularly in the UEs. Previous studies have demonstrated significant correlations between HGS and the strength of various UE muscle groups [15,23,24]. In this study, the AHGS and DHGS were used as outcome measures.

HGS was measured in kilogram-force (kgf) using an electronic dynamometer (Camry Electronic, Zhongshan, China). The testing posture followed a standardized protocol established by the American Society of Hand Therapists [25]. The participants were seated upright in a chair with their feet flat on the floor. The shoulder was maintained in adduction and neutral rotation, the elbow was flexed at 90°, and the forearm was in a neutral position. The wrist was positioned between 0° and 30° of extension, and between 0° and 15° of ulnar deviation. In all patients, the arm was not supported by either the examiner or armrest. During measurement, the dynamometer was held in a vertical position and aligned with the forearm to ensure standardized positioning of the forearm and wrist [25-27].

The measurement protocol was as follows. Each patient underwent a single warm-up trial before testing. Subsequently, tests were administered on both the unaffected and affected sides, with each trial lasting 3 seconds. Three trials were performed, and the mean of the recorded values was used for the analysis. A 60-second rest period was provided between trials. All measurements were performed in an outpatient setting between 2:00 PM and 5:00 PM [28-32].

4. Statistical analysis

The general patient characteristics are summarized using descriptive statistics. Quantitative variables are presented as the mean±standard deviation and median (interquartile range). Qualitative variables are expressed as frequencies. Generalized estimation equations were applied to compare the VAS, AHGS, and DHGS scores at different time points (pretreatment, immediately after treatment, 1 week after treatment, and 2 weeks after treatment). Adjusted analyses were conducted using age and sex as covariates. Multiple comparisons were performed by using the least significant difference test. The obtained data were analyzed by a medical statistician. All statistical analyses were performed using IBM SPSS ver. 19.0 for Windows (IBM Corp., Armonk, NY, USA). A p-value of <0.05 was considered significant.

Results

1. Patient characteristics

The patient cohort in this study comprised seven male and three female patients, with a median age of 46.4 years (range, 35–78 years). The affected disc levels were C5–6 in five patients, C6–7 in three patients, and C5–6–7 in two patients. None of the patients had undergone surgery specifically on the cervical spine, and other medical histories included hypertension, diabetes mellitus, Raynaud disease, and subarachnoid hemorrhage due to rupture of an anterior communicating artery aneurysm. The left side was affected in six patients, whereas the right side was affected in four patients (Table 1).

Table 1.

Baseline demographic and clinical characteristics of the study participants

Characteristic	Data
No. of patients	10
Age (yr)	46.40±13.09
Sex
Male	7 (70.0)
Female	3 (30.0)
Body mass index (kg/m2)	27.10±4.62
Medical history
Hypertension	2 (20.0)
Diabetes mellitus	1 (10.0)
Raynaud’s disease	1 (10.0)
Subarachnoid hemorrhage	1 (10.0)
Cervical spine level
C5–6	5 (50.0)
C5–6–7	2 (20.0)
C6–7	3 (30.0)
Lesion
Left	6 (60.0)
Right	4 (40.0)

Values are presented as number only, mean±standard deviation, or number (%).

2. Changes in the visual analog scale score

The mean VAS scores for the neck and UEs before CEB (pre-CEB) were 7.2±0.42 and 6.3±0.51, respectively. At 2 weeks after CEB (Week2), the mean VAS scores decreased to 2.9±0.37 for the neck and 2.8±0.38 for the UEs, indicating significant pain reduction (neck, p<0.001; UEs, p<0.001). Adjusted analyses incorporating patient age and sex as covariates demonstrated similar findings, confirming significant improvements in neck and UE pain (neck, p<0.001; UE, p<0.001) (Table 2).

Table 2.

Changes in VAS scores for neck pain and upper extremity radiating pain before and after CEB

Variable	VAS		p-valuea)	p-valueb)
	Pre-CEB	Week2
Neck	7.2±0.42	2.9±0.37	<0.001	<0.001
Upper extremity	6.3±0.51	2.8±0.38	<0.001	<0.001

Values are presented as the mean±standard error.

VAS, visual analog scale; UE, upper extremity; CEB, cervical epidural block; Week2, 2 weeks after CEB.

^a)p-values were obtained by generalized estimating equation.

^b)Adjusted p-values were obtained using age, sex, and body mass index as covariates.

3. Changes in handgrip strength

The mean AHGS values pre-CEB, immediately after CEB (Immediate), 1 week after CEB (Week1), and Week2 were 23.13±2.60, 27.77±2.66, 26.95±2.50, and 26.18±2.77, respectively. A significant increase in muscle strength was observed over time (p<0.001). Patients demonstrated improved muscle strength in the Immediate, Week1, and Week2 measurements compared with that in the pre-CEB measurement. However, no significant differences were noted among the Immediate, Week1, and Week2 measurements. Adjusted analyses incorporating patient age and sex as covariates yielded consistent results, confirming significant changes in the AHGS over time (p<0.001) (Table 3, Fig. 1A).

Table 3.

Changes in AHGS and DHGS before and after CEB

Variable	Pre-CEB1	Immediate2	Week13	Week24	p-valuea)	p-valueb)
AHGS (kgf)	23.13±2.60	27.77±2.66	26.95±2.50	26.18±2.77	<0.001 (1<2,3,4c))	<0.001 (1<2,3,4c))
DHGS (kgf)	10.24±2.78	7.54±2.56	6.80±2.23	7.40±2.10	<0.001 (1>2,3,4c))	<0.001 (1>2,3,4c))

Values are presented as mean±SE error.

AHGS, affected side handgrip strength; DHGS, difference in handgrip strength; CEB, cervical epidural block; Immediate, immediately after CEB; Week1, 1 week after CEB; Week2, 2 weeks after CEB.

^a)p-values were obtained using the generalized estimating equation.

^b)Adjusted p-values were obtained using age, sex, and body mass index as covariates.

^c)Multiple comparison results were compared using the Bonferroni correction.

Fig. 1.

Mean values of (A) affected side handgrip strength (AHGS) and (B) difference in handgrip strength (DHGS) before cervical epidural block (CEB) and immediately (Immediate), 1 week (Week1), and 2 weeks (Week2) after CEB. SE, standard error.

The mean DHGS pre-CEB, Immediate, Week1, and Week2 values were 10.24±2.78, 7.54±2.56, 6.80±2.23, and 7.40±2.10, respectively. A significant decrease in muscle strength difference was observed over time (p<0.001). The difference in muscle strength was lower at Immediate, Week1, and Week2 than at pre-CEB. However, no significant differences were noted among the Immediate, Week1, and Week2 measurements. Adjusted analyses incorporating general patient characteristics, including age and sex as covariates, yielded consistent results, confirming significant changes in DHGS over time (p<0.001) (Table 3, Fig. 1B).

Discussion

In this study, we investigated the effects of CEB on pain relief and muscle strength in patients with CDH. The findings demonstrated that CEB not only alleviated pain but also improved HGS, with both effects maintained for up to 2 weeks after the injection.

The prevalence of CDH increases with age in both men and women, with the highest incidence observed between 30 and 50 years of age, particularly in women. The most affected cervical disc levels are C5–6 and C6–7 [14]. The pathophysiology of disc herniation involves a combination of mechanical compression of the nerve by the herniated nucleus pulposus and localized inflammatory responses mediated by cytokine release, resulting in pain and sensorimotor deficits. Depending on the severity of nerve compression, varying degrees of microvascular compromise may occur, ranging from venous congestion and edema due to mild compression-induced venous insufficiency to arterial ischemia resulting from severe compression [33]. Additionally, neural irritation caused by the herniated disc can stimulate further cytokine production, whereas mechanical stretching of the nerve root through the intervertebral foramen may exacerbate symptoms [34].

Most patients (75%–90%) with acute cervical radiculopathy secondary to disc herniation experience symptom improvement through nonoperative management [35,36]. Conservative treatment options include cervical bracing, pharmacological therapy, and physical therapy, with CEB serving as a commonly employed, minimally invasive alternative to surgical intervention. However, approximately one-third of patients continue to experience persistent symptoms despite nonoperative treatment [35]. If symptoms persist for >6 weeks, the likelihood of spontaneous resolution without surgical management decreases significantly [35,36].

We evaluated the effects of CEB on pain relief and improvement in HGS in patients with CDH. The findings revealed significant improvements in both pain intensity, as measured by VAS, and HGS, as indicated by AHGS and DHGS, compared with the pretreatment values. These therapeutic effects were sustained for up to 2 weeks after treatment. The relationship between pain intensity and grip strength is inconsistent in the literature. Some studies indicated significant associations or grip strength improvements after radiculopathy treatment, whereas others found no direct correlation between self-reported pain scores and objective muscle strength. Owing to the small sample size and exploratory nature of our pilot study, we did not perform a formal correlation analysis between HGS and VAS scores. This mixed evidence underscores the need for adequately powered prospective studies to clarify the mechanistic link between analgesia and motor recovery [15,37-39].

This study had some limitations. First, the relatively small sample size limits the generalizability of our findings. Second, the absence of data from nerve conduction studies, electromyography, and quantitative sensory testing resulted in an incomplete assessment of neuromuscular function. Third, although the observed improvement in muscle strength is notable, evidence confirming whether this enhancement translates into functional performance gains remains unknown. Future studies incorporating functional assessment tools such as the Short Form-36 questionnaire may provide further insight into changes in physical function and emotional well-being. Fourth, as the C5–7 nerve roots do not directly influence HGS, the assessment of myotome-specific muscle strength would have provided a more precise evaluation. However, HGS remains a valuable indicator of overall UE muscle function and serves as a simple, reliable, and clinically practical measure for evaluating general muscle strength [23-25]. Finally, the 2-week follow-up period was insufficient to evaluate the long-term sustainability of the therapeutic effects.

Therefore, CEB may be an effective treatment option to alleviate pain and improve HGS in patients with CDH. This study highlights the potential benefits of CEB in alleviating pain and muscle weakness. Further large-scale studies are required to validate these findings and to assess the long-term effects of CEB.