ORIGINAL RESEARCH ARTICLE
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Effects of Adding a Neurodynamic Mobilization to Motor Control
Training in Patients With Lumbar Radiculopathy Due to Disc
Herniation
A Randomized Clinical Trial
Gustavo Plaza-Manzano, PT, PhD, Ignacio Cancela-Cilleruelo, PT, MSc,
César Fernández-de-las-Peñas, PT, MSc, PhD, Dr med, Joshua A. Cleland, PT, PhD, José L. Arias-Buría, PT, PhD,
Marloes Thoomes-de-Graaf, PT, PhD, and Ricardo Ortega-Santiago, PT, PhD
Objective: The aim of the study was to investigate the effects of the
inclusion of neural mobilization into a motor control exercise program
on pain, related disability, neuropathic symptoms, straight leg raise,
and pressure pain threshold in lumbar radiculopathy.
Design: This is a randomized clinical trial.
Methods: Individuals with low back pain, with confirmed disc herniation, and lumbar radiculopathy were randomly assigned to receive
eight sessions of either neurodynamic mobilization plus motor control
exercises (n = 16) or motor control exercises alone (n = 16). Outcomes
included pain, disability, neuropathic symptoms, straight leg raise, and
pressure pain threshold at baseline, after four visits, after eight visits,
and after 2 mos.
Results: There were no between-groups differences for pain, related
disability, or pressure pain threshold at any follow-up period because
both groups get similar and large improvements. Patients assigned to
the neurodynamic program group experienced better improvements
in neuropathic symptoms and the straight leg raise compared with
the motor control exercise group (P < 0.01).
Conclusions: The addition of neurodynamic mobilization to a motor
control exercise program leads to reductions in neuropathic symptoms
and mechanical sensitivity (straight leg raise) but did not result in
greater changes of pain, related disability, or pressure pain threshold
over motor control exercises program alone in subjects with lumbar
radiculopathy. Future trials are needed to further confirm these findings
because between-groups differences did not reach clinically relevance.
What Is Known
• Motor control exercises are effective for the management of low back pain. Some evidence supports the
use of neural mobilization in low back pain, but its evidence for radicular pain is poor. We do not know
whether combined interventions would lead to better
outcomes.
What Is New
• The addition of neurodynamic mobilization to a motor control exercise program leads to some reduction
in neuropathic symptoms and mechanical sensitivity
but did not result in greater changes of pain, related
disability, or pressure pain sensitivity over the application of motor control exercises program alone in subjects with lumbar radiculopathy.
ow back pain (LBP) is a common condition, resulting in a
Lity. The
significant impact on the patient in terms of pain and disabilcosts associated with LBP are increasing exponentially.
In addition, many individuals with LBP also experience the consequence of a disk herniation, for example, radiating pain and
radicular symptoms, which may result in lower limb symptoms,
such as radiculopathy.2 Lumbar radiculopathy may be the result
of a herniated lumbar disc, which may irritate a lumbar nerve
trunk resulting in intraneural inflammation. A herniated disk
could cause lower limb numbness and weakness in addition
to pain experienced by the individuals. Unfortunately, lumbar
radiculopathy can progress to chronicity resulting in substantial pain, disability, and burden.3
There are several treatment strategies for the management
of LBP and lumbar radiculopathy including disc surgery, injections, analgesia, acupuncture, traction, manual therapy,
percutaneous discectomy, exercise, and/or orthosis.4 Although
optimal management strategy for lumbar stenosis, including
From the Department of Radiology, Rehabilitation and Physiotherapy, Universidad
Complutense de Madrid, Madrid, Spain (GP-M); Instituto de Investigación Sanitaria del Hospital Clínico San Carlos, Madrid, Spain (GP-M); Clínica Fisiofit,
Madrid, Spain (IC-C); Department of Physical Therapy, Occupational Therapy,
Rehabilitation and Physical Medicine, Universidad Rey Juan Carlos, Alcorcón,
Madrid, Spain (CF-d-l-P, JLA-B, RO-S); Cátedra de Investigación y Docencia en
Fisioterapia: Terapia Manual, Punción Seca y Ejercicio Terapeútico, Universidad
Rey Juan Carlos, Alcorcón, Madrid, Spain (CF-d-l-P, JLA-B, RO-S); Physical
Therapist, Rehabilitation Services, Concord Hospital, Concord, New Hampshire
(JAC); Faculty, Manual Therapy Fellowship Program, Regis University, Denver,
Colorado (JAC); Department of Physical Therapy, Franklin Pierce University,
Manchester, New Hampshire (JAC); and Fysio-Experts, Hazerswoude-Rijndijk,
the Netherlands (MT-d-G).
All correspondence should be addressed to: César Fernández-de-las-Peñas, PT, MSc,
PhD, Dr med, Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos,
Avenida de Atenas s/n, 28922 Alcorcón, Madrid, Spain.
Trial registration: http://www.clinicaltrials.gov, ClinicalTrials.gov, NCT03620864.
Financial disclosure statements have been obtained, and no conflicts of interest have
been reported by the authors or by any individuals in control of the content of
this article.
Supplemental digital content is available for this article. Direct URL citations appear
in the printed text and are provided in the HTML and PDF versions of this article
on the journal’s Web site (www.ajpmr.com).
Copyright © 2019 Wolters Kluwer Health, Inc. All rights reserved.
ISSN: 0894-9115
DOI: 10.1097/PHM.0000000000001295
Key Words: Lumbar Radiculopathy, Exercise, Neurodynamic, Pain,
Disability
(Am J Phys Med Rehabil 2020;99:124–132)
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American Journal of Physical Medicine & Rehabilitation • Volume 99, Number 2, February 2020
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Volume 99, Number 2, February 2020
Neurodynamic Intervention in Lumbar Radiculopathy
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radiculopathy, remains to be elucidated, current trends are conservative interventions, such as physical therapy.5 Moreover,
according to an international survey, surgeons around the
world indicated one of the assumptions for an operative intervention is the failure of conservative therapy, thereby implying
that conservative therapy is the first treatment option.6 Surgery
is not more effective than physical therapy after 1 yr on pain relief and perceived recovery.7,8 Many physical therapy treatment options exist, including manual therapies and exercises;
however, the best method to decrease pain and improve function in people with LBP and leg pain associated with lumbar
radiculopathy is not currently known.9
The most recent Cochrane review found moderate- to
high-quality evidence supporting the use of motor control exercises for the management of LBP, although no differences were
found with other forms of exercise.10 There also exists evidence supporting the use of manual therapies, such as spinal
manipulation or mobilization for the management of LBP.11
However, different manual therapies, for example, soft tissue
interventions, spinal manipulation or mobilization, and neural
interventions, target different concepts.
A manual therapy technique that may potentially be used
for the management of patients with lumbar radiculopathy is
neurodynamic mobilization. Neural mobilization includes both
slider and tensioner maneuvers. The aim of a nerve slider intervention is to induce a gliding movement of the nerve trunk in
relation to their adjacent tissues. The nerve slider technique applies joint movements to the targeted structure proximally
while releasing the movement distally, followed by a reverse
combination.10 In the contrary, the aim of a nerve tensioner intervention is to induce tension of a nerve trunk in relation to
their adjacent tissues. The nerve tensioner technique applies
joint movements to the targeted structure proximally and distally at the same time and in the same direction toward an increase in nerve tension.10 It has been postulated that if the
nervous system (lumbar nerve root) is irritated, the system
may present with neural edema, ischemia and fibrosis, leading
to further damage resulting in pain and decreased function.12,13
The underlying mechanisms of neural mobilization interventions include restoration of homeostasis in and around the
nerve and reducing intraneural edema through intraneural fluid
dispersion in the nerve root and axon.14–16
Cleland et al.17 used a neurodynamic mobilization technique to manage a patient with lumbar radiculopathy in which
the individual experienced clinically meaningful reductions in
pain. However, no high-quality evidence exists in relation to
this particular approach individuals with lumbar radiculopathy.18
A recent meta-analysis reported that neural mobilization is effective for improving pain and disability in individuals with
LBP, but the evidence for the use of neural mobilization for radicular pain was found to be poor.19 Future trials examining
the effects of neural mobilization in people with lumbar
radiculopathy are necessary to determine its efficacy.
Therefore, the purpose of this randomized clinical trial
was to investigate the effects of the addition of neural mobilization into a motor control exercises program on pain,
disability, and pressure sensitivity in individuals with
lumbar radiculopathy. Our hypothesis was that subjects
with lumbar radiculopathy receiving neural mobilization
combined with a motor control exercise program would
experience better outcomes than those receiving motor control exercise program alone.
METHODS
Study Design
A randomized, parallel-group, clinical trial was conducted
to compare the effects of adding a neurodynamic mobilization
into a motor control exercise program on pain intensity, neuropathic symptoms, related disability, straight leg raise test, and
pressure pain sensitivity in individuals with lumbar radiculopathy.
The study was approved by the institutional review board of
Universidad Alcalá de Henares, Spain (CEIM/HU/201531) and
the trial was registered (ClinicalTrials.gov: NCT03620864). This
trial conforms to CONSORT guidelines and reports the required
information accordingly (see Supplemental Checklist, Supplemental Digital Content 1, http://links.lww.com/PHM/A859).
Participants
Between July and October 2018 consecutive patients
exhibiting LBP and radiculopathy (lower limb symptoms) were
screened for potential eligibility criteria from a local hospital in
Madrid, Spain. To be eligible to participate, patients (a) had to
be between 18 and 60 yrs old, (b) have a confirmed (via MRI)
disc herniation between L4-S1 levels, (c) had to exhibit lumbar
radiating pain to one lower limb including the foot, (d) have
had pain for at least 3 mos, (e) had increased leg pain on
coughing, sneezing, or straining, and ( f ) had a positive
straight leg raise with symptom reproduction between 40
and 70 degrees. All participants received a neurological clinical examination including assessment of muscle weakness,
cutaneous sensitivity, and reflexes by an experienced neurologist for evaluating the integrity of the nervous system and
avoiding the presence of lumbar radiculopathy. Manual muscle
tests were performed to identify the presence of weakness
along L4-S1 myotome distribution by using the grading of 0
to 5 (0/5 no movement, 3/5 antigravity, 5/5 normal). Subjects
were excluded if they had any of the following criteria: (a) indication for surgical intervention, for example, absence of reflexes, muscle atrophy, and signs compatible with lumbar
myelopathy, (b) had a confirmed disc herniation at other lumbar
levels, (c) have had any other spinal conditions such as spinal tumors, spondylolisthesis, or cauda equina, (d) had received treatment for this condition by a physical therapist the previous 6 mo,
or (e) pregnancy. Participants were also excluded if they exhibited any contraindications to manual therapy or exercise as noted
in the patient’s Medical Screening Questionnaire, such as rheumatoid arthritis, osteoporosis, prolonged history of steroid use,
severe vascular disease, etc. All subjects signed an informed
consent before participation in the study.
All participants provided a detailed history, underwent a
physical examination, and completed a number of self-report
measures at baseline. The historical items included questions
pertaining to the onset of sensory symptoms including pain,
pins or needles, the distribution of the symptom, aggravating
and easing postures, mechanism of injury, previous treatments,
and history of low back or leg pain. These physical examination items were those that are routinely used in the physical
therapy examination of the lower limb.
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Plaza-Manzano et al.
Randomization and Masking
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Subjects were randomly assigned to receive either motor
control exercises plus neurodynamic mobilization or a motor control exercise program alone. Concealed allocation was performed
by an individual not involved in subject’s recruitment using a
computer-generated randomized table of numbers created before
the beginning of the trial. The group assignment was recorded on
an index card. This card was folded in half such that the label with
the patient’s group assignment was on the inside of the fold. The
folded index card was then placed inside the envelope, and the
envelope was sealed. A second therapist blinded to the baseline
examination findings opened the envelope and proceeded with
treatment according to the group assignment.
Treatment Interventions
All interventions were applied by an experienced physical
therapist with more than 10 yrs of experience in the management of patients with lumbar radiculopathy.
Both groups received 8 sessions of a motor control exercise program of 30-min duration for 4 wks, twice a week, following expert recommendations,20,21 and as previously used
by Costa et al.22 On each session, the therapist corrected each
subject individually to ensure correct technique and ensured
that the participant was confident to perform the exercises
alone at home. Participants were asked to perform exercises
at home once daily for 20 mins for the 8-wk intervention period.
The motor control exercise program consisted of a progression
from isolated contraction of the transversus abdominis and/or isolated contraction of the multifidi to combined contraction of both
transversus abdominis and multifidi muscles in different positions
from supine or prone to bridging or four-point kneeling (Fig. 1).
Each participant was progressed on exercises when they have
reached an independent activation of the transversus abdominis
and multifidus without overactivity of superficial muscles in an
individualized manner (visual observation by the therapist). Each
exercise was performed for 10 repetitions for 10 secs each as
previously described.22 The adherence to the exercise program
was collected on each subsequent session in a weekly diary.
Patients allocated to the neurodynamic group also received a nerve neurodynamic slider intervention targeting the
main trunk of the sciatic nerve of the affected side. Previous
studies have suggested that nerve slider techniques are associated with larger nerve excursion than nerve tensioner interventions.23,24 The nerve slider intervention applied in the current
study included flexion, adduction and medial rotation (if possible) of the hip, knee extension, and ankle dorsiflexion. From
this position, concurrent hip flexion and knee flexion were alternated dynamically with concurrent hip and knee extension
(Fig. 2). During the intervention, the therapist alternated the
movement combination depending on the tissue resistance and
patient’s symptoms. Speed and amplitude of movement were
adjusted such that no pain was produced during the technique.
The slider intervention was applied for 3 sets of 10 repetitions
on each treatment session for 8 wks, and it was applied 5 mins
before the motor control exercise program.
Outcome Measures
All outcomes were assessed at baseline, after four treatment sessions (mid follow-up), after the treatment program
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FIGURE 1. Monitoring correct contraction of the transversus abdominis
(A), multifidi (B), or both combined (C) in different positions (supine,
prone, four-point kneeling).
(immediate follow-up), and 2 mos after the last treatment session (follow-up) by an assessor blinded to the group allocation
of the subjects.
The primary outcome was the intensity of lower limb pain
symptoms. Participants rated the intensity of their lower limb
pain at rest on an 11-point numeric pain rating scale (NPRS)
where 0 represents no pain and 10 is the maximum pain.25 Because there is no specific minimum clinically important difference (MCID) for NPRS in individuals experiencing lumbar
radiculopathy, we used the MCID established as 2 points for
patients with LBP.26 The cutoff of 2 points is usually considered an MCID for chronic pain in general.27
Secondary outcomes included the Self-report Leeds Assessment of Neuropathic Symptoms and Signs Scale (S-LANSS), the
Roland-Morris Disability Questionnaire (RMDQ), the straight
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scored “No,” i.e., the denominator remains. The score ranges
from 0 to 24 with higher scores indicative of higher related disability. The MCID for the RMDQ has been reported to range
from 2 to 8 points.32 Lauridsen et al.33 found that the RMDQ
also exhibited good responsiveness for patients with leg pain
showing a MCID of 5 points.
The straight leg raise test examines the sensitivity of the
sciatic nerve. It is performed passively with patients in supine.
The clinician lifts the leg while maintaining the knee extended.
Reproduction of the patient symptoms between 40 and 70 degrees is considered as indicative of a disc herniation comprising a nerve root. The straight leg raise has shown a sensitivity
of 91% and specificity of 26%.34 Neto et al.35 found that
changes ranging from 7 to 8 degrees can be considered minimal detectable difference for the straight leg raise test,
whereas Dixon and Keating36 reported that intersession measurements need to change by more than 16 degrees to represent a relevant change.
Pressure pain sensitivity was assessed by pressure pain
thresholds (PPTs), that is, the minimal amount of pressure applied on a particular point for the pressure sensation to first
change to pain.37 A mechanical pressure algometer (Pain Diagnosis and Treatment Inc, New York) was used in this trial to assess PPTs (kilogram per square centimeter) over the common
peroneal (where it passes behind the head of the fibula as it
winds forward around its neck) and tibial (where it bisects
the popliteal fossa, lateral to the popliteal artery) nerve trunks
of the affected leg. The reliability of PPT assessment over these
nerve trunks has been found to range from moderate to high.38
All participants were instructed to press the switch when the
sensation changed from pressure to pain. The mean of three trials was calculated on each point and used for the analysis. A
30-sec resting period was allowed between each measure.
The order of assessment was randomized between subjects.
Treatment Adverse Effects
At each session, patients were asked to report any adverse
events that they experienced. In the current trial, an adverse
event was defined as sequelae of 1-wk duration with symptoms
perceived as distressing and unacceptable to the patient and required further treatment.39
FIGURE 2. Nerve slider intervention targeting the sciatic nerve. First,
flexion, adduction and medial rotation (if permitted) of the hip, knee
extension, and ankle dorsiflexion are applied (A). From this position,
concurrent hip flexion and knee flexion (B) are alternated dynamically
with concurrent hip and knee extension (C).
leg raise test, and pressure pain sensitivity. The S-LANSS is a
simple and valid seven-item tool for identifying individuals whose
pain is dominated by neuropathic mechanisms.28 Each item is a
binary response (yes or no) to the presence of symptoms (five
items) or clinical signs (two items). The total score is 24 points
and a value of 12 points or higher is indicative of a neuropathic
component of pain. In the current trial, the validated Spanish version of the S-LANSS was used.29
The RMDQ is one of the most comprehensively validated
outcome measures for LBP.30 To score the RMDQ, the number
of items checked by the patient is tallied (yes/no).31 If patients
indicate that an item is not applicable to them, the item is
Sample Size Determination
The sample size was calculated using Ene 3.0 software
(Autonomic University of Barcelona, Spain) and was based
on detecting between-groups difference of 2.0 points on a
NPRS,26,27 assuming a standard deviation of 1.4, a two-tailed
test, an α level of 0.05, and a desired power (β) of 80%. The
estimated desired sample size was calculated to be of 16 subjects per group.
Statistical Analysis
Data were analyzed using the SPSS Version 21.0 (SPSS
Inc, Chicago, IL) program. Means, standard deviation, and
95% confidence intervals were calculated for each variable.
The Kolmogorov-Smirnov test revealed a normal distribution
of all the quantitative data (P > 0.05). Baseline demographic
and clinical variables between groups were compared using independent t test for continuous data and χ2 tests of independence
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for categorical data. A mixed-model 4 2 analysis of covariance
(ANCOVA) with time (before, mid follow-up, immediate followup, 2 mos) as the within-subjects factor, group (motor control or
motor control plus neurodynamic) as the between-subjects factor,
and sex as covariate was used to examine the effects of the interventions on each outcome (ie, pain intensity, S-LANSS,
straight leg raise, and PPTs). For each ANCOVA, the hypothesis of interest was the group time interaction. In general,
a P value of less than 0.05 was considered statistically significant, but post hoc analyses were conducted with a Bonferroni
test using a corrected α of 0.025 (2 independent samples).
The effect size was calculated when the η2p was significant.
To determine the clinical effect sizes, standardized mean score
differences (SMDs) were calculated by dividing the mean
score differences between groups by the pooled standard deviation. In general, an SMD of 0.2 is considered small, 0.5 moderate, and 0.8 large clinical effect size.
RESULTS
Forty consecutive subjects with symptoms in the lower
limb compatible with lumbar radiculopathy were screened
for potential eligibility between July and October 2018.
Thirty-two patients satisfied all criteria, agreed to participate, and were randomly allocated to the motor control exercises (n = 16) or motor control exercise plus neurodynamic
intervention (n = 16) group. The reasons for ineligibility
are listed in the flow diagram of patient recruitment and retention (Fig. 3). Baseline features between both groups were
similar for all outcomes (Table 1). None of the subjects receiving either intervention reported any adverse events. The
adherence to the exercise program was 96% as collected on
the weekly diary.
Pain Intensity
The ANCOVA did not find a significant group time interaction for lower limb pain (F = 1.269, P = 0.273, η2p =
0.043): patients receiving motor control exercises program
alone or combined with a neurodynamic intervention experienced similar decreases in lower limb pain (Table 2, Fig. 4A).
Between-groups effect sizes were small (SMD = 0.2),
whereas within-group effect sizes were large for both groups
FIGURE 3. Flow diagram of participants throughout the course of the study.
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Neurodynamic Intervention in Lumbar Radiculopathy
TABLE 1. Baseline demographics and clinical data by treatment assignment*
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Motor Control (n = 16)
Motor Control + Neurodynamic (n = 16)
P
8:8
45.5 ± 6.0
17.3 ± 1.4
8 (50%):8 (50%)
6.0 ± 1.4
12.0 ± 1.3
10.5 ± 2.6
53.2 ± 10.0
8:8
47.0 ± 8.0
17.2 ± 1.5
7 (44%):9 (56%)
5.9 ± 1.4
12.0 ± 1.1
11.2 ± 1.5
55.2 ± 6.5
0.999
0.605
0.781
0.682
0.912
0.998
0.567
2.3 ± 1.0
3.4 ± 0.9
2.1 ± 0.9
3.2 ± 0.6
0.565
0.521
Sex, male/female
Age, yr
History of pain, mo
Symptoms limb, left/right
Mean pain intensity (NPRS, 0–10)
S-LANSS (0–24)
RMDQ (0–24)
Straight leg raise, degree
PPTs, kg/cm2
Common peroneal
Tibialis
*Data are expressed as means ± standard deviation, except for sex and symptoms limb.
(SMD > 1.25). Sex did not influence the effect in the main
analysis (F = 0.895, P = 0.355).
Neuropathic Symptomatology (S-LANSS)
The ANCOVA revealed a significant group time interaction for S-LANSS (F = 8.559, P = 0.008, η2p = 0.373): patients
in the motor control exercise plus neurodynamic intervention
group exhibited a greater decrease in the S-LANSS score (suggesting a decrease of neuropathic symptoms) than those in the
motor control exercise alone group (Table 2, Fig. 4B). Betweengroups effect sizes were large immediately after treatment
(SMD = 0.95) and at 2 mos (SMD = 0.75). Sex did not influence the interaction on the S-LANSS (F = 0.211, P = 0.651).
Related Disability (RMDQ)
The results did not reveal a significant group time interaction for the RMDQ (F = 2.970, P = 0.101, η2p = 0.023):
patients in both groups experienced similar decreases in related
disability (Table 2, Fig. 4C). Between-groups effect sizes were
small (SMD = 0.18), whereas within-group effect sizes were
large for both groups (SMD > 1.15). Sex did not influence the
main effect in the analysis (F = 0.202, P = 0.658).
Mechanical Pain Sensitivity (Straight Leg Raise
and PPT)
The ANCOVA revealed a significant group time interaction for the straight leg raise (F = 7.512, P = 0.013,
η2p = 0.220): individuals in the motor control exercise plus
neurodynamic intervention group exhibited greater improvements in the straight leg raise test (suggesting a decrease of mechanical sensitivity) than those in the motor control exercise
alone group (Table 2, Fig. 4D). Between-groups effect sizes
were moderate (SMD = 0.55) after four treatment sessions
and large immediately after the treatment (SMD = 1.05) and
TABLE 2. Evolution of the outcomes by randomized treatment assignment
Outcome Group
Baseline
Pain intensity in the lower limb (NPRS, 0–10)
Motor control
6.0 ± 1.4 (5.1, 6.9)
Motor control + NDS
5.9 ± 1.4 (5.0–6.8)
S-LANSS (0–24)
Motor control
12.0 ± 1.3 (11.5–12.5)
Motor control + NDS
12.0 ± 1.1 (11.8–12.2)
RMDQ (0–24)
Motor control
10.5 ± 2.6 (9.5–11.5)
Motor control + NDS
11.2 ± 1.5 (10.0–12.4)
Straight leg raise, degree
Motor control
53.2 ± 10.0 (48.2–58.2)
Motor control + NDS
55.2 ± 6.5 (51.2–59.2)
PPTs over the tibial nerve, kg/cm2
Motor control
3.4 ± 0.9 (3.1–3.7)
Motor control + NDS
3.2 ± 0.6 (2.9–3.6)
PPTs over the common peroneal nerve, kg/cm2
Motor control
2.3 ± 1.0 (1.8–2.8)
Motor control + NDS
2.1 ± 0.9 (1.7–2.5)
After 4 Sessions
After 8 Sessions
4.7 ± 1.1 (4.0–5.4)
4.3 ± 1.0 (3.7–4.9)
3.4 ± 0.9 (3.0–3.8)
2.5 ± 0.8 (2.0–3.0)
3.2 ± 0.8 (2.8–3.6)
2.6 ± 0.8 (2.2–3.0)
10.7 ± 1.0 (9.8–11.6)
10.5 ± 1.1 (9.7–11.3)
9.5 ± 0.9 (8.7–10.3)
6.6 ± 0.8 (5.8–7.4)
8.4 ± 1.5 (7.2–9.6)
6.5 ± 1.6 (5.5–7.5)
8.2 ± 1.3 (7.0–9.4)
7.7 ± 1.5 (6.6–8.8)
6.2 ± 1.2 (5.2–7.2)
5.6 ± 1.1 (4.5–6.7)
5.9 ± 1.2 (5.9–6.8)
5.2 ± 1.4 (4.4–6.0)
58.9 ± 11.3 (52.9–64.9)
64.1 ± 11.2 (57.1–71.1)
62.7 ± 12.7 (57.6–67.8)
73.9 ± 10.1 (67.9–79.9)
2 mos
63.1 ± 12.8 (56.9–69.3)
71.9 ± 9.8 (65.7–78.1)
3.7 ± 0.8 (3.3–4.1)
3.6 ± 0.7 (3.2–4.0)
4.2 ± 1.0 (3.7–4.7)
4.1 ± 0.7 (3.7–4.5)
4.0 ± 1.1 (3.5–4.5)
4.0 ± 0.8 (3.6–4.4)
2.5 ± 0.9 (2.1–2.9)
2.6 ± 0.4 (2.2–3.0)
2.9 ± 0.8 (2.5–3.3)
3.0 ± 0.7 (2.6–3.4)
2.8 ± 0.8 (2.4–3.2)
2.8 ± 0.5 (2.4–3.2)
Values are expressed as mean ± standard deviation (95% confidence interval).
NDS, neurodynamic intervention.
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FIGURE 4. Evolution of leg pain intensity (A), S-LANSS (B), RMDQ (C), and straight leg raise (D) throughout the course of the study stratified by
randomized treatment assignment. Data are means (standard error).
at 2-mo follow-up (SMD = 0.9). Sex did not influence the main
interaction on the straight leg raise (F = 0.994, P = 0.331).
Finally, no significant group time interactions for
changes in PPTs in the tibial (F = 0.582, P = 0.454,
η2p = 0.026) or common peroneal (F = 0.658, P = 0.426,
η2p = 0.029) nerve trunks were observed: patients receiving motor control exercises alone or combined with a neurodynamic intervention experienced similar increases in PPTs (Table 2).
Between-groups effect sizes were small (SMD = 0.14),
whereas within-group effect sizes were large for both groups
(SMD > 1.04). Sex did not influence the interaction effects
on PPTs (tibial: F = 0.678, P = 0.420; common peroneal:
F = 0.620, P = 0.440).
DISCUSSION
This is the first clinical trial examining the effects of
adding nerve neurodynamic mobilization to a program of motor control exercises compared with motor control exercises
alone in individuals with lumbar radiculopathy. Our results
demonstrated that the addition of nerve mobilizations did not
result in a greater change on leg pain, related disability, or
PPT over motor control exercises in this population; however,
those receiving motor control exercises/neurodynamic mobilizations experienced significantly greater reductions in neuropathic symptoms (S-LANSS) and mechanical sensitivity
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as measured by the straight leg raise test suggesting that
neurodynamic mobilizations may have a greater impact on
nerve tissue sensitivity.
Although the exact mechanisms underlying the effects of
manual therapies are uncertain,40 a number of potential theories exist as to how manual therapies, including neurodynamic
nerve mobilizations, might exert their therapeutic effects. It is
possible that neurodynamic mobilization may have the ability
to alter descending inhibitory pain mechanisms,41 to modify
blood flow to regions in the brain associated with pain,42 and
reduce activation of supraspinal pain centers.43 However, these
mechanisms would be expected to have an impact on patientcentered outcomes, such as pain and disability, which has been
identified in studies using neurodynamic treatments for individuals with nerve entrapment of the upper limb, for example,
carpal tunnel syndrome.44 The fact that no between-groups differences were observed for pain intensity and related disability
may be associated to the fact that there is evidence supporting
the application of motor control exercises for the management
of this population.10 Both groups obtained significant and
large clinical effects, which may support the positive effect of
motor control exercises; however, the lack of a control group
and the small sample size do not permit us to conclude this.
Participants receiving the neurodynamic intervention experienced large improvements in neuropathic symptoms and
the impact on neural sensitivity as assessed by the straight leg
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Neurodynamic Intervention in Lumbar Radiculopathy
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raise. It should be noted that between-groups differences at
2-mo follow-up for the straight leg raise (8.8 degrees)
surpassed the minimal detectable difference reported by Neto
et al.35 but not the cutoff (16 degrees) determined by Dixon
and Keating36 supporting a potential, but small, effect of
the neurodynamic mobilization in this outcome. In addition,
it should be noted that the straight leg raise does not only assess neural sensitivity because it can be also associated with
hamstring tightness.
It is also important to note that both groups decreased significantly their S-LANSS scores, although the neurodynamic
mobilization groups exhibited a greater and larger decrease.
After all treatment sessions, almost all participants in both
groups were below the 12-point cutoff that determines the presence of neuropathic symptoms supporting that both interventions may be capable of reducing neuropathic symptoms,
although changes were superior when a neurodynamic mobilization was included into the treatment program. Several
hypotheses explaining changes in these outcomes can be
proposed. For example, a cadaveric study performed on
the tibial nerve found that neurodynamic mobilization resulted
in dispersion of intraneural fluid,15 which might assist in a reduction of intraneural edema found in individuals experiencing
neural compression.45 Another cadaveric study examining a potential impact of simulated neurodynamic mobilization technique on sections of the sciatic nerve also found dispersal of
intraneural fluid, which was hypothesized for resulting to decreased intraneural edema and intraneural pressure.14 However,
these hypothesis in people with actual nerve compression requires further research. It is interesting to note that a study comparing nerve and tendon glides to splinting in subjects with
carpal tunnel syndrome, a neuropathic condition of the wrist,
showed that both interventions resulted in similar reduction on
intraneural edema.46 However, splinting is not a viable option
for individuals with lumbar radiculopathy.
It should also be noted that the effect sizes for changes in
the S-LANSS and straight leg raise test were much larger after
eight sessions as compared with when measured after just four
sessions. It is difficult to determine the dosage (number of
treatment sessions) necessary to maximize patient outcomes.
The topic of tolerance or a decrease in magnitude of effect over
time is an area of discussion. For example, Fernández-de-lasPeñas et al.47 found that after receiving consecutive sessions
of thoracic manipulation, patients continued to receive added
benefit with additional visits. Another study comparing the
dose response of spinal manipulation, comparing 0, 6, 12,
and 18 sessions, found that 12 sessions of spinal manipulation
were best for maximizing changes in pain and disability in individuals with chronic LBP at a 12-wk follow-up.48 Therefore,
the ideal dose response for neurodynamic mobilizations requires further investigation but from the current results, it
seems that eight treatments result in superior outcomes when
compared with four treatments.
Study Limitations
Finally, there are several limitations to the current study
that should be considered. Only one therapist provided all the
techniques at one geographical location. Although this enhances
the internal validity, it potentially reduces the generalizability of
current findings. Second, we included a relatively small sample
size, which could be underpowered to identify a difference on
some outcomes. Furthermore, the sample was restricted to patients with disc herniation between L4-S1 level, so we do not
know whether these results would be similar in patients with
disc problems at other lumbar levels. Similarly, the lack of control for the magnitude (size and spinal cord location) of the disc
herniation could limit the results. Finally, we only included a
2-mo follow-up. Future clinical trials should include additional
clinicians from different locations, larger sample sizes, and collect outcome measures at long-term follow-up.
CONCLUSIONS
The results of the current trial performed on individuals
with LBP, confirmed disc herniation, and radiculopathy, observed that they did not experience greater improvements in
pain, function or PPTwhen they received neurodynamic mobilization in addition to motor control exercises. However, although patients receiving neural mobilizations experienced
greater changes in neural mechanosensitivity as measured by
the S-LANSS and straight leg raise; these differences were
small and probably not clinically relevant. Future clinical trials
are needed to further confirm these findings.
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