Rehabilitation of permanent bilateral brachial neuralgia with mechanical allodynia
Catherine COUTURE
MSc(A) OT, CSTP®, School of Rehabilitation, Faculty of Medicine and Health Sciences, McGill University, Montreal (Qc), Canada
Abstract
A 264-month history of neuropathic pain was resolved using the method of Somatosensory Pain Rehabilitation (SPR). Therapist and patient noted a reduction in allodynia, initially in degree and then in overall area. A territory of underlying hypo-aesthesia was exposed thereafter and it was treated to prevent relapse. This case report illustrates the use of the SPR method in occupational therapy for treating allodynia and its underlying hypo-aesthesia for a patient with bilateral permanent brachial neuralgia in the upper extremities in an unprecedented speed of 107 days of treatment. The different stages of evaluation and treatment are discussed in detail.
Keywords: Neuropathic pain, allodynia, underlying hypo-aesthesia, somatosensory pain rehabilitation, occupational therapy
Introduction
The method of Somatosensory Pain Rehabilitation (SPR) was developed to diagnose and treat neuropathic pain, based on the phenomenon of pain and current knowledge about the functioning of the somatosensory nervous system, i.e., adaptative neuroplasticity (Spicher et al. 2020a). A frequent feature of neuropathic pain is mechanical allodynia, that is, “pain due to a stimulus which does not normally provoke pain” (Merskey & Bogduk, 1994) and it is commonly found in neuropathic pain conditions such as permanent or intermittent neuralgia. Static Mechanical Allodynia (SMA) is, paradoxically, a painful touch-evoked tactile hypoaesthesia (Bowsher, 1993; Spicher et al., 2008). Recent studies show favorable results using the SPR method to decrease neuropathic pain (Packham et al., 2018).
Occupational therapy services enable people to engage in everyday living through occupation (Townsend & Polatajko, 2007). According to the Canadian Association of Occupational Therapists (CAOT), Occupational Therapists (OTs) should engage in practices that integrate quality pain management services across the lifespan and that focus on prevention of chronic, enduring pain (CAOT, 2012). Pain, especially chronic pain, is an all-encompassing condition which affects daily activities and quality of life and has repercussions in the workplace, and on the family and social environment (Dueñas et al., 2016). Knowing the unique contribution that OTs can make to chronic pain management, can the SPR method address permanent neuralgia with SMA and support return to meaningful occupations for individuals with chronic pain?
The aims of this case report, is to discuss the effectiveness of the SPR method in occupational therapy on permanent neuralgia (stage IV of Aβ axonal lesions) with SMA. The method will be exemplified through the presentation of a patient diagnosed with bilateral permanent brachial neuralgia of the anterior branch of medial cutaneous nerve of the right and left forearms (stage IV of Aβ axonal lesions) with mechanical allodynia (Spicher et al., 2020b). By adhering rigorously to the SPR method and recommendations, the patient was able to see his bilateral SMA and its underlying hypo-aesthesias resolved and return to his meaningful occupations.
Patient & Methods
Patient
The patient is a 54-year-old Caucasian male presenting with excruciating pain in both upper extremities following a traumatic injury. At the time of the first assessment, this pain had been present for 264 months. As a consequence, the patient suffered from restless nights where he woke 3-8 times due to pain. He was unable to drive anymore due to pain, fatigue, and medication. His job functions had been altered to accommodate his current state and he was working part time (50% workload). His goals were to get back to working full time in the same work setting and to return to driving and participating in family activities.
Methods
Upon admission, and then on an ongoing basis, patients are assessed using the SPR method.
McGill Pain Questionnaire (MPQ)
The perception and evolution of the patient’s pain was assessed using the French version of the MPQ (Melzack, 1975): the Questionnaire de la Douleur St-Antoine (QDSA) (Boureau et al., 1984). This is a valid and reliable tool to qualify and quantify the multidimensional nature of pain and is sensitive to change over time (Katz & Melzack, 1999). It is especially helpful in enabling the patient and the therapist to define and quantify pain and it also makes a useful distinction between sensory and affective pain. In the SPR method, the MPQ is used as an outcome measure, but also as an ongoing evaluation tool throughout treatment.
Allodynography
Allodynography (Spicher, 2006; Spicher et al., 2008) is a technique which enables the therapist to quantify and map the territory of Static Mechanical Allodynia (SMA) on the skin, that is, it provides a visual understanding of the allodynic area of the skin. The assessment is conducted by applying a 15-gram aesthesiometer across the skin surface in 4 directions (distal, proximal, lateral, medial) towards the presumed affected cutaneous branch in order to delineate the borders of the SMA territory. This is done in collaboration with the patient with the use of a visual analogue scale (VAS) where 3 cm is defined as a positive pain response and serves as a determinant of the border of the allodynic territory.
Rainbow Pain Scale (RPS)
The RPS is used to determine the degree of the SMA within the allodynic territory and to identify the area of its most intense pain. It uses 7 different aesthesiometers, ranging from 0.03 to 15 grams of pressure (Spicher 2006; Spicher et al., 2008; Packham et al., 2020b). Using the finest aesthesiometer, 0.03 gram (colour red on the RPS), the therapist begins to stimulate the patient’s skin within the allodynic territory. If this does not elicit a pain response, the therapist then proceeds to the next, thicker, aesthesiometer 0.2 gram, (colour orange on RPS). The assessment continues working through 7 aesthesiometers until a positive pain response is provoked on skin simulation. Once the severity is identified, the therapist uses the identified aesthesiometer to map the territory of skin which is painful with this aesthesiometer. To do so, the therapist moves towards the center or the most painful skin area with the aesthesiometer until the patient perceives that the pain begins (3cm on VAS).
Underlying Aesthesiography
Upon a negative allodynography, the search for an underlying hypo-aesthesia of the cutaneous territory begins because SMA has been found to be a “Paradoxically painful hypo-aesthesia” (Spicher et al., 2008). The underlying aesthesiography is used to assess the territory of underlying hypo-aesthesia. The therapist uses a normed aesthesiometer (usually 0.7 grams) and moves towards the center or the autonomous territory of the affected cutaneous nerve branch of the previously painful skin area to identify its borders.
Rehabilitation at Home and in the Clinic
In the SPR method, the patients are assessed and treated by two different therapists using a cotherapy model of practice. The method is organized on the basis of one weekly session, alternating between the two therapists. The duration of each weekly therapy session ranges between 30 to 75 min. The therapeutic management regime of the SMA is: (1) The prescription “not to touch when possible” the affected area and (2) Distant Vibrotactile Counter-Stimulation (DVCS) on a comfortable area to be done daily, six to twelve times a day, for 15 seconds or less time, and in therapy once a week (Spicher et al., 2020a). The RPS is evaluated weekly to assess its size and severity, and the allodynography monthly. Following a negative allodynography, rehabilitation of the underlying hyposensitivity, based on neuroplasticity, is started with gradual “hands on” therapy (Spicher et al., 2020a) with the goal of gradually waking-up the dormant cutaneous territory by stimulating collateral nerve sprouting of nearby healthy axons (Lundborg, 2004).
The following describes the relationship between the MPQ results with the shrinking of the allodynic territory and the subsequent decreased clinical signs of underlying hypo-aesthesia. The patient presented with permanent brachial neuralgia of the anterior branch of medial cutaneous nerve of the right and left forearms (stage IV of Aβ axonal lesions) with mechanical allodynia. He was seen weekly over a period of 107 days for SPR. An overview of the results of the allodynography, the RPS and the subsequent somesthetic clinical evaluations can be found in No Comment Nb 42 (Couture, 2022).
Results
The MPQ results evolved as follow (Table I):
Table I: The decrease in MPQ scores on the first day, halfway through treatment and on the last day.
Allodynography
The patient having two distinct painful areas (one on each arm), it was decided that SPR would begin with the patient’s dominant right arm. During the initial assessment, the therapist made a hypothesis as to which cutaneous nerve branch was damaged, completed the allodynography and determined the degree of the allodynia with the RPS. The allodynography was positive and the severity recorded was indigo (8.7 grams increases the VAS to 4.8cm). The left arm was evaluated two weeks later. The allodynography was positive and the severity recorded was yellow (0.7 grams increases the VAS to 4.8).
Underlying Aesthesiography
After the allodynography was found to be negative (right arm: day 58, left arm: day 79), an underlying hypo-aesthesia was found beneath both allodynic territories on the cutaneous branches. The evolution of the sensations of touch were evaluated with the Pressure Perception Threshold (PPT), the 2-Point Discrimination Test, and the Vibration Perception Threshold (VPT) (Spicher et al., 2020). The normalization of these results correlated with a decrease in MPQ scores. Complete results can be found in No Comment Nb 42 (Couture, 2022).
Impact on occupations
The patient increased his working hour volume from 50% to 100% by day 62 of treatment. By Day 107, he returned to driving and leisure activities. He no longer woke at night due to pain.
Discussion
The results show a unique and unprecedented speed of recovery for this patient’s static mechanical allodynia, especially on the left side. Indeed, it normally takes about 1 month to remove one color on the RPS before moving on to the next (Spicher et al., 2020a). In the case of a yellow pain scale, one would expect the allodynography to be negative in approximately five months. Yet in this case, the patient’s allodynography was negative after only one month. Despite these surprising results, we can observe a regular progression of the recovery of skin sensitivity on the hypo-aesthetic territory in about one month after the allodynography was found to be negative. One must keep in mind that such rapid results are rare, but recovery does occur in 73% of treatments at the Somatosensory Rehabilitation Centre in Fribourg, Switzerland (Wagner et al., 2021). The impact of this recovery on the patient’s life was tremendous. After 264 months of pain and sleepless nights, the client’s MPQ scores showed improvements not only on the sensory scales, but also on the affective scales. The patient was able to return to work full-time, resume his role of being a parent and return to meaningful leisure activities (driving, hiking, etc.). OTs “believe that the experience of pain is bio‐psychosocial. As such, pain impacts all aspects of occupation and being across the life span and can be associated with the full range of physical and mental health conditions” (CAOT, 2016). As such, OTs, equipped with the SPR method, are well placed to support patients with neuropathic pain in returning to their occupations.
Conclusion
A 264-month history of neuropathic pain with SMA was resolved using the method of SPR. Considering the prevalence of neuropathic pain (Couture & Spicher, 2022) and its impact on occupations, OTs would benefit from learning the SPR method in order to better help their patients return to their meaningful occupations. It would, however, be interesting to evaluate patients’ perspectives and satisfaction through the use of occupation-focused assessment tools to better understand how this method supports their return to meaningful occupations.
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