Abstract
Background and Purpose: The sport of ultramarathon running has seen an exponential just in recent participation and, with it, studies of injury rates have been conducted. The purpose of this case is to detail the conservative physical therapy treatment peripheral neurogenic pain in an ultramarathon runner secondary to edematous entrapment of the common fibular nerve and associated sensory branches, through the clinical use of IASTM and supportive treatments.
Case Description: The patient is a 40-year-old male who presents approximately 4 weeks post 8-day 380-mile intermittent run. As a result of this event, the patient developed edema and resultant sensory and motor nerve impairments. Sensation to light touch produced both no sensation reported and a nociceptive stimulus described as “painful tingling” by the patient.
Intervention: Interventions included in this study aimed to mobilize soft tissue and neural elements while also addressing strength and ROM deficits. Interventions included: soft tissue massage, neural mobilization, static stretching, sensory re-education of cutaneous receptors and strengthening exercises.
Outcomes: The patient demonstrated improvements in both sensation location and intensity as well as the response to stimuli. Neural tension was negative upon discharge with improvements in AROM, PROM and muscular strength reported. Additionally, the patient reported a significant improvement in functional self-report using the Lower Extremity Functional Scale (LEFS).
Conclusions: This report could be used as an effective protocol in a single case-by-case basis, however limitations in the absence of a control and a follow up limit the use of this protocol to provide long term reduction in symptoms from an entrapment of the CFN in a larger patient population.
Introduction
There exists a relatively small group of recreational runners who test the physical limits of the human body by running multiple ultramarathons, any distance longer than a standard marathon, 42.195 kilometers1, which is roughly 26.2 miles. Growth of the ultramarathon sport has occurred exponentially in recent years.2 Still this group of extremists remains a small percentage of recreational runners.2,3 Age of ultramarathon finishers has been found ranging from 15 to 75 years old, and research suggests that peak ultramarathon performance can be realized even at the ages of 40 and older.3 A comparison between ultramarathon runners and the general population reveals decreased prevalence of chronic diseases and mental health disorders among this highly active group.4
While overall health and functioning is a relative concept, ultramarathon runners possess their own predisposition to physical impairment. Secondary to the nature of the sport, ultramarathon runners who present for medical treatment are often suspected of having compartment syndrome, stress fracture, nerve entrapment/compression,5 dehydration or exercise-associated hyponatremia (EAH)1 as well as a host of other musculoskeletal injuries4. An observational field study from 2012 illustrated the positive relationship between fluid intake and the volume of the foot; observable and measurable swelling of the foot.6 Swelling of local compartments of the lower leg can be a primary irritant for nervous and connective tissue5 and, through a damaging cycle of fibrosis, be a secondary source of neural irritation through myofascial restriction7. One such nerve which has been shown to have a predisposition to entrapment in the lower leg is the common fibular nerve (CFN), also referred to as the common peroneal nerve1.
Certain anatomical features along the pathway which the Common Fibular Nerve and its’ deep, superficial, and sensory branches course leave this nerve vulnerable to potential entrapment.1 The CFN originates from the 4th and 5th lumbar spinal nerves (L4-L5) down to sacral (S) nerves, S1-S2, and initially its path travels with the sciatic on the posterior aspect of the leg. At the location just inferior to the fibular head, is the first location of potential fascial nerve entrapment of both the CFN and associated sensory lateral sural cutaneous and recurrent articular nerve. Here, the recurrent articular nerve receives sensory information from the anterior knee, while the lateral cutaneous nerve receives sensory information from the distal half of the lower leg. In addition, the lateral sural cutaneous nerve anastomoses with a branch of the tibial nerve, medial sural cutaneous nerve, to form the sural nerve. The more distal and second location for potential entrapment, is found just before the CFN divides into the deep and superficial fibular nerves, lying superficial to a fascial layer known as the posterior crural intermuscular septum; deep to the peroneus longus muscle.8 See table 1 under examination for motor innervations of the deep and superficial fibular nerves. View figure 1 in the Index for sensory innervation of the superficial fibular nerve (A) as well as the sural (B), lateral sural cutaneous nerves (C), and deep fibular nerve (D).
An entrapment of, or damage to, the CFN can result in peripheral neurogenic pain9 which can manifest hypersensitivity to touch9, often described as painful tingling, burning or prickling sensations, in addition to possible numbness.10 In more severe cases this can manifest as weakness of the ankle dorsiflexors and everters, resulting in gait disturbances.1
Documented methods of relieving nerve entrapment and associated symptoms in the lower leg have included both surgical nerve decompression and conservative physical therapy treatment. While surgical options quickly alleviate fascial sources of compression and have shown successful outcomes, conservative management of mild to moderate lower leg nerve entrapments have also demonstrated positive outcomes.11 Manual therapy practices, such as soft tissue massage and neural mobilization have been utilized with good outcomes for nerve entrapment.11 The use of secondary tools, often called Instrument Assisted Soft Tissue Mobilization (IASTM), has been shown to have a positive effect on nerve conduction velocity, wrist strength and wrist motion in a patient with carpal tunnel syndrome compared with traditional soft tissue massage.12 There is, however, limited research on the effect of IASTM in conjunction with supportive soft tissue mobilization techniques to treat peripheral neurogenic pain. The purpose of this case is to detail the conservative physical therapy treatment peripheral neurogenic pain in an ultramarathon runner secondary to edematous entrapment of the common fibular nerve and associated sensory branches, through the clinical use of IASTM and supportive treatments.
Case Description and History
This is the case of a 40-year-old male patient who presented to PT with a diagnosis of “nerve entrapment” from his primary care physician with orders to evaluate and treat. The patient was an avid long-distance runner and, on the day of the evaluation, was approximately four weeks post an 8 day, 390-mile intermittent run. Each day consisted of roughly 15 minutes of stretching, followed by 1 to 2 miles of walking and anywhere from a 23 to 51 mile run on paved road. The patient noted he only ran on the right side of the road; with the flow of traffic. A support team accompanied the patient by van to provide food, water, shelter, therapeutic modalities and encouragement. Modalities consisted of ice and massage, specifically the use of a foam roller; to which the patient recalls extreme discomfort during his event. The patient reported that he initially wore “shin-splint” compression sleeves on his lower legs the first two days until edema in the ankles was noted (See figure 2 in index). The remainder of the 6 day trek the patient reported wearing compression socks which covered the leg from the toes to just below the knee. The patient recalls severe swelling in bilateral lower extremities for the remainder of the 8 days which did not fully subside until approximately one week after completion of the run.
The patient presented with a chief complaint of “painful” tingling noted along the posterior-lateral and lateral calf and numbness of the lateral ankle, with the right lower extremity worse than the left. The patient reported a gradual onset of these symptoms toward the end of his 8-day journey and continuing shortly thereafter. In the three weeks which proceeded his event, the patient reported he had continued to run his normal average of about 7 miles at least 5 days a week in the presence of symptoms. Using the Numeric Pain Scale Rating (NPSR), the patient reported a 0/10 pain at best and a 7/10 at worst, specifically while putting on shorts, drying off after a shower, and upon contact with sheets while sleeping. (See Table 1) The NPSR has been shown to have excellent concurrent validity compared with the Visual Analogue Scale (r= 0.86).13 Utilizing the Lower Extremity Functional Scale, an 80-point self-report questionnaire, the patient reported a score of 70/80 or a 12.5% impairment on the LEFS. (See table 1) The LEFS has been shown to be a reliable tool (r=.86 for test retest reliability), with good construct validity of the physical component, r=.80 in comparison to the SF-36 physical function subscale measuring functional musculoskeletal impairment.14 The primary functional limitation reported was while bending or squatting to put on socks and shoes without an increase of symptoms. The patient denied any other pertinent medical problems at that time. As a goal for physical therapy, the patient wanted to be able to continue running and performing everyday activities without increased sensitivity.
Initial clinical impression of the patient’s presentation was an entrapment of the sural nerve secondary to the buildup of edema during and after the multiple-day ultramarathon. In addition, the patient described feelings of weakness of bilateral lower extremities leading to a suspicion of motor nerve involvement.
Patient Examination
A physical examination was performed by a student physical therapist under the supervision of a licensed DPT. The most significant objective findings are detailed below and objective measures can be seen in table 1.
Upon initial observation and palpation for condition, mild atrophy of the lateral compartment of both the right and left lower legs was noted. Joint active ranges of motion (AROM) and passive ranges of motion (PROM) were tested according to the principles of Norkin and White4; measurements are outlined in table 1. Bilaterally AROM and PROM of classic ankle dorsiflexion, with both the knee flexed and extended were limited. Active and passive active inversion were also limited in both the right and left lower extremity, with a patient report of symptom reproduction. All other ranges of motion testing were found to be insignificant.
Manual muscle testing of the lower extremity with the patient in supine was performed according to the principles of Kendall.16 Listed in table 1, active ankle dorsiflexion, eversion as well as extension of the great toe and toes 2-5 demonstrated impaired functional strength. All other lower extremity muscles were graded as a 5/5. Tinnel’s test, at the location of the fibular head, tested positive bilaterally, with reproduction of the patient’s painful tingling sensation. Tinel’s test which has shown a sensitivity of 62% and a specificity of 93% in helping to diagnose carpal tunnel syndrome, a nerve entrapment of the upper extremity.17 The patient reported bilateral tenderness with palpation of light to moderate pressure, as noted by the physical therapist, of the gastrocnemius, soleus and peroneus longus/brevis muscles.
Outcome Measures
Initial Evaluation (session 1)
Discharge
(session 5)
Left
Right
Left
Right
Joint AROM
DF Knee Flexed
12°
12°
20°
20°
DF Knee Extended
8°
9°
18°
18°
Inversion
16°
20°
27°
30°
Joint PROM
DF Knee Flexed
15°
15°
22°
22°
DF Knee Extended
12°
14°
20°
20°
Inversion
17°
22°
30°
32°
Manual Muscle Test
Peroneus Longus
4-/5
3+/5
4+/5
4+/5
Peroneus Brevis
4-/5
3+/5
4+/5
4+/5
Peroneus Tertius
4
4
4+
4+
Tibialis anterior
4+/4
4+/4
5/4
5/4
Extensor Digitorum Longus/Brevis
3+/5
3+/5
4/5
4/5
Extensor Hallucis Longus
4/5
4/5
5/5
5/5
Extensor Hallucis Brevis
4/5
4/5
4+/5
4+/5
Functional Self-Report
LEFS
70/80= 12.5% impairment
80/80= 0% impairment
Table 1: Object findings of outcome measures in a case of CFN entrapment.
A lower extremity neurovascular screen demonstrated neural tension and hypersensitivity to light touch. Neural tension was noted with a standard slump test, the predictive validity of which is under debate. One study, which examined the concurrent validity (r=0.64) between the straight leg raise and slump test in patients with leg pain stated that these tests could be appropriate to test the mechanosensitivity of the lower extremity.18 Sensitivity to light touch was measured by stroking suspected areas of sensory involvement with a cotton ball 10 times, while the patient’s eyes were closed and recording the number of incorrect and painful responses to a light touch stimulus, see table 2 for results. A body chart was used to illustrate the report of quality and location of sensations felt during light touch sensation testing at baseline. Initially, symptoms distal to the location of the posterior crural intermuscular septum demonstrated numbness, while those prior to this location, but distal to the fibular head demonstrated heightened and painful response to light touch stimuli. For reference, areas of sensation not suspected to be involved were demonstrated using the same technique. Dorsalis pedis artery and posterior tibial artery pulses were present and demonstrated a grade of 3, or normal, according to the commonly used scale to measure palpated distal pulses.19
Patient Evaluation
Examination data gathered supported the original hypothesis of a sensory nerve entrapment with motor involvement. Sensory testing demonstrated bilateral impairment to all sensations tested in the distribution of CFN branches, including the superficial fibular, the sural and lateral sural cutaneous nerves. Strength testing revealed mild weakness of the muscles innervated by the common fibular nerve, specifically the superficial and deep fibular branches. Secondary to the hypothesized nature of edematous entrapment following the patient’s run, it was suspected that fibrotic adhesions and potentially stagnant fluid might have compressed these nerves. As a result of the patient continuing to run, a continuous irritant to his lower extremities, perhaps the cycle of fibrosis7 has been allowed to continue to compress and restrict the CFN and its associated sensory branches.
Consistent with symptoms demonstrated in bilateral lower extremities, it was hypothesized that the hard and consistent surface of the road, on which the patient ran, could have had an effect on the presentation of greater sensation impairment on the right. Roads are often consistent and non-conforming to the feet whereas the natural surface of the earth offers greater variability in level and inclination between the feet as well as a more pliable contact with the feet. Additionally, roads add another variable in they possess camber, or angular horizontal slope of each side of the road designed to facilitate water drainage.20 A study by Kristian O’Connor and Joseph Hamill demonstrated the effect that a cambered road has on rear foot kinematics and suggested that running on a cambered road might predispose runners to injury.20 The degree to which the camber of a road truly influences the risk of injury has been the topic of much debate, with some scholars believing a small amount can have a significant impact,21 while others dismiss any clinical relevance.22
Regardless of the facts of these debates, the patient’s symptoms in this case mirrored this theory that running only on one side, the right, of a cambered road might leave a runner more susceptible to injury. Perhaps the leg length discrepancy between the right and left legs, the change in rear foot kinematics, over the course of 8 days is to blame for the greater sensation deficits in the right lower extremity. Examination data highlighted a physical therapy diagnosis of edematous entrapment of bilateral common fibular nerves and adjacent branches, with secondary tension of the right lower extremity lateral compartment nerves.
Plan of Care
The physical therapy plan of care, based upon the impairments found, centered around the need to restore mobility of the soft tissues of the lower leg, re-educate the proper response of sensitive nerve endings and improve the strength of bilateral lower extremities. Functionally, the goal of this plan was to allow the patient to be able to squat, put on socks and shoes, and run 5 miles without increased sensitivity; demonstrating an ability to participate in a 10k race. With the suspected mechanism of nerve entrapment being myofascial restriction and residual edematous fluid, prognosis was excellent considering the patient’s age, activity level, and motivation to decrease symptoms and avoid any reoccurrence. Therapists at this clinic had found success using ASTYM tools to break up fascial restrictions and scar tissue, so this was considered to be a common treatment. In addition to myofascial and soft tissue mobilization principles, neural glides and sensitivity retraining were implemented to facilitate healing and re-education of neural tissues. The patient’s insurance provider was not accepted at this clinic and, as a result, the patient was paying out-of-pocket for physical therapy services. Treatment sessions, including the initial evaluation, were limited to five 1-hour visits with more of an emphasis placed on patient education and compliance with a home exercise program.
Intervention/ Reassessment
Due to the limited number of visits, patient related instruction was one of the more important aspects of this plan of care. The second visit, the patient stated that he would be participating in another multiple-day run in the spring. Details of this trek differed from his previous one in that it was a relay in which each person runs a set distance, far less than his first trek, however the event would take place over a greater period of time. Knowing that this patient was passionate about doing this, patient education on prevention of any reoccurrence of this injury was essential. Initially, the patient was educated on care for the hypersensitive areas, such as avoiding possible irritants, patting dry, as opposed to whipping off, after a shower. The patient was also educated on the importance of stretching and a dynamic warm-up prior to his runs. Specific patient education for his next long trek included the potential effects of compression sleeves/socks and the role this can play in edema management as well as the need to change running surface, to perhaps avoid risk of a repetitive overuse injury.20
Prior to treatment using IASTM suction and scrape tools (figure 3 and 4 in index) a reassessment of sensitivity to light touch sensation was performed using the technique described in the examination section. In addition, the LEFS was administered at initial evaluation and discharge to demonstrate change in functional status. A recent study examining the effect of IASTM on tissue extensibility dysfunction, utilized a warm up of 5 minutes of stationary biking followed by 5 minutes with the use of tools to mobilize soft tissues.23 Found to have a positive effect on sports participation,23 a similar approach was used with regard to IASTM treatment time. The patient warmed up with 8 minutes on a recumbent bike before any manual therapy was begun. A study by Sudarshan Anandkumar (2012) demonstrated effective use of soft tissue and neural mobilization, in addition to pain modalities, in the treatment of a superficial fibular nerve entrapment.11 In the case of this patient pre-treatment soft tissue interventions were performed to the patient’s tolerance, including longitudinal and transverse manipulations to the posterior-lateral and lateral lower legs and transverse friction massage to the Achilles tendon. The intent of these techniques was to relieve tension and continue to warm myofascial and cutaneous tissues, while manual stretch of the gastroc/soleus aimed to improve extensibility of the impaired tissue.11 Similar to the study by Anandkumar, neural mobilizations were utilized to break fascial adhesions which might surround neural tissue, though they differed in technique. See figure 5 for neural mobilization technique performed. With the patient reclined, foot supported with knee flexion at 90 degrees, suction cupping was applied to the posterior-lateral and lateral lower leg in small circular patterns for approximately 150 seconds. Immediately following this treatment, “scraping,” using the tool in figure…, in the direction of distal to proximal was performed to patient tolerance, stopping with discomfort which reaches a 4 on the NPSR. Following this treatment, the patient was allowed a few minutes to relax prior to beginning sensory re-education exercises. Sensory re-education exercises included the use of the light touch examination technique for 3 sets of 20 repetitions, with the patient’s eyes closed; noting when sensation was felt. Additional exercises performed aimed to address minor strength deficits, including standing heel raises initiated the second visit and blue theraband resisted eversion of the feet, initiated the third visit. Each exercise was performed for 3 sets of 10, with focus on slow eccentric control.
The patient demonstrated good compliance with home exercise program (HEP) and was eager to see improvements in his condition. With the limited number of visits, the patient was expected to perform several exercises at home. Home exercises included static stretching of gastroc/soleus, neural glides, and sensory retraining using various stimulus. Beginning the second treatment, the patient was encouraged to apply a soft stimulus such as a cotton ball, or soft touch using the hand, to the lower extremities to tolerance 5 minutes per day. By the fourth visit, the patient’s tolerance to light touch had improved and so a rougher texture, a washcloth, was implemented. At discharge, the patient was encouraged to add material such as newspaper to his sensory re-education regimen.
Outcomes
Using the functional pain scale, at discharge the patient identified a pain rating of 2 (slight pain) at worst; an improvement from 7 at baseline. This is improvement is clinically significant (MCID=1.7 points) according to a study of pain perception in chronic pain patients.24 The location of the patient’s pain and reports of increased sensitivity also demonstrated improvements from baseline measures using. The body chart at discharge was noted to have a small area (approximately 1.5 inch in height) of increased sensitivity reported on the lateral aspect of the Achilles tendon. Additionally, a small, roughly quarter sized location of numbness was identified just inferior to the lateral malleolus at discharge. These changes in body chart demonstrate the change in pain location in this patient. Objective measurement of sensitivity to light touch demonstrated improvements bilaterally as seen in table 2, though there are no psychometric studies to validate this measure.
Light touch sensation testing
Initial Evaluation (1st visit)
2nd Visit
3rd Visit
4th Visit
Discharge (5th visit)
Right LE
9/10
8/10
6/10
3/10
1/10
Left LE
8/10
5/10
4/10
2/10
0/10
Note- each reported in # of incorrect responses or responses of symptom reproduction.
Table 2: Objective measurement of light touch sensitivity.
See Table 1 for all results related to PROM, AROM, strength testing and LEFS. Both PROM and AROM noted improvements in both range and symptom reproduction and studies have shown the validity in comparing impairment measures, such as cervical ROM, with functional limitations (r=0.82).25 Manual muscle testing revealed improvements in a full grade of the Peroneus Longus and Brevis, which, according to Cuthbert and Goodheart (2007), denotes significant change in muscle strength.26 All other changes in strength were considered to be insignificant. The subjective self-report LEFS demonstrated a change from a score of 70 at baseline, to 80, or 0% impairment, at discharge. This change in LEFS score is greater than the Minimally Clinical Important Difference (MCID) identified in previous research.25
At discharge, the patient’s subjective statements expressed both physical and emotional improvements had occurred since the initial evaluation. Taking a mental note each time the patient experienced symptoms of increased sensitivity to touch throughout the day, at discharge the patient reported decreased frequency and intensity. Frequency of which was reported to occur only a maximum of two times per day since the fourth visit. The patient reported that he has been able to bend, squat and put on his socks and shoes to run his normal distance without symptoms of pain and increased sensitivity.
Discussion
Conservative management of lower extremity nerve entrapment has been shown to have positive effects on symptoms, and research has focused on the use of neural mobilizations, soft tissue mobilization and static stretching to treat this condition.11 Limited research exists which studies the effect of soft tissue mobilization through the use of secondary tools and its effect on peripheral neurogenic pain, specifically in a population whose sport participation can potentially facilitate continuation of the cycle of fibrosis. The results of this study serve to suggest that IASTM can be an effective tool, used in conjunction to treat a nerve entrapment of the lower. While the absence of a control variable, to observe differences between IASTM and traditional conservative treatment, limit the generalization of this plan of care/treatment technique to a larger patient population, the results of this case are supported by the results of similar studies. The study by Anandkumar (2012) demonstrates the resolution of painful symptoms, after only 6 visits, from superficial peroneal entrapment using traditional principles including soft tissue mobilization, neural mobilization and pain modalities.11 To contrast, the plan of care in this case utilized similar traditional principles, including soft tissue massage and neural mobilization, in conjunction with suction and scraping IASTM techniques, to alleviate symptoms of the larger, more proximal CFN in only 5 visits. Follow up research should investigate the influence of combinations the techniques utilized in this study to establish a better understanding of how to order manual treatment in the case of nerve entrapment.
Research which has explored the use of IASTM has demonstrated the positive effect it can have in treatment of tissue extensibility dysfunction,23 short term improvements in ranges of motion, nerve conduction velocity improvements,12 and response of peripheral mechanoreceptors to discriminate between 2 points or pressure.27 Similar effects have been illustrated with only the use of traditional techniques and, perhaps the evidence gathered from these studies might help to explain these result, as simply improving tissue extensibility and range of motion alone could have worked to facilitate improved nerve conduction and sensory ability.
The patient was not able to be reached for a 4-month follow up, further limiting the significance of the present study. While the targeted use of IASTM proved to have a significant effect on peripheral neurogenic pain in this case of a 40-year-old ultramarathon runner over the course of 5 visits, this study warrants the further investigation into the long-term effects of IASTM and traditional techniques on edematous entrapment of the common fibular nerve.
Index:
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