A Graphic Designer’s Allodynia and Spontaneous Neuralgia Treated with the Method of Somatosensory Pain Rehabilitation

Marie-An HOANG [2], [3], Florine ETIÉVANT [4], [3], Christoph C ERLING [5] & Claude J SPICHER [6], [3]

Abstract

Introduction: Post carpal tunnel release surgery, a right-handed graphic designer and artist suffered from two differing neuropathic pain conditions: neuralgia and Static Mechanical Allodynia (SMA). The patient suffered from intermittent brachial neuralgia of the proper palmar radial digital nerve D4 (stage III of Aβ axonal lesions) with SMA. Neuralgia describes spontaneous pain along the affected nerve branch. SMA is pain provoked by tactile stimulation. After thirteen months of ineffective desensitization treatment, the patient trialed the method of Somatosensory Pain Rehabilitation (SPR). The aim of this case report is to describe the effectiveness of this method in treating neuropathic pain.

Methods: The patient’s SMA was first assessed and treated by a Certified Somatosensory Therapist of Pain (CSTP®). Once the SMA was resolved, the patient and CSTP® treated the underlying tactile hypo-aesthesia presumed responsible for the neuralgia.

Results: After thirteen months of the method of SPR, the patient’s neuropathic pain was resolved. The patient no longer experienced touch-evoked and spontaneous pain on her right hand. The patient’s satisfaction to be able to carry out work and leisure activities increased.

Discussion: The method of SPR was effective in treating the patient’s neuropathic pain. Given the equal level of research evidence between SPR and desensitization, therapists are encouraged to change their treatment method when the trial of one treatment is not appropriate nor efficient for their patients. Discussions with their patients about the efficacy of recommended therapeutic interventions could be a good indicator of when a switch in treatment is needed.

Keywords: neuralgia, allodynia, tactile hypo-aesthesia, somatosensory pain rehabilitation, neuropathic pain

Introduction

Neuropathic Pain – Neuralgia – Neurogenic Pain

Neuropathic pain is defined as ‘‘pain arising as a direct consequence of a lesion or disease affecting the somatosensory system”[1]. The Atlas of Cutaneous Branch Territories for the Diagnosis of Neuropathic Pain, based on a prospective cohort study of 3142 patients, states that the presentation of neuropathic symptoms is indicative of at least one cutaneous nerve branch lesion, including Aβ neurofibers[2]. Neuralgia and static mechanical allodynia (SMA) are placed under the umbrella term, “neuropathic pain”, obscuring the distinction between the two different neuropathic pain conditions.

In ancient Greek, the prefix “neur” refers to “relating to the nerve” (νευρου) and the suffix “- algia” refers to “pain” (ἄλγος). In the 1800s, neuralgia described spontaneous pain caused by nerve injury[3]. In the 1990s, Melzack and Wall further defined neurogenic pain as permanent and incessant[4]. Today, neuralgia is similarly characterized as Aβ axonal lesions causing (1) burning sensations within a specific territory; (2) sensations of electrical quality (e.g., shooting) along a nerve branch[5], [6]; and/or (3) strange sensations of “numbing” and/or “tingling”, as Aβ axonal lesions generate a tactile hypo-aesthesia[6]. Thus, neuralgia is the peripheral expression of a partial tactile hypo-aesthesia, resulting from a damaged nerve branch [7-9], occasionally covered by a paradoxical painful touch-evoked tactile hypo-aesthesia —SMA[10-12]. SMA is pain caused by a tactile “stimulus that does not normally provoke pain”[13] and results from large diameter myelinated Aß neurofibers lesion[14].

An e-Delphi survey of 43 international hand therapist experts found the three most common tactile stimulation approaches to treat SMA: desensitization, somatosensory relearning and counterstimulation[15]. The most frequently employed sensory treatment of SMA, desensitization was defined as stimulating directly the painful area by 69% of therapists[15]. In contrast, sensory relearning was understood as touching next to or around the painful territory by 28% of therapist and counterstimulation as “touching in a distant anatomically associated cutaneous nerve branch”[15] by 51% of therapists[15]. Research highlights that there is no consensus on the appropriate treatment of SMA; it is undetermined whether tactile stimulation of the painful area (e.g., desensitization) is more effective than the avoidance of tactile stimulation of the territory (e.g., somatosensory relearning and counterstimulation). Given the equal level of evidence of the different treatment approaches, there remains a lack of research that support therapists in selecting the appropriate and effective treatment for their patients living with neuropathic pain.

Patient Information

The patient is a right-handed, 44-year-old woman. She underwent a successful carpal tunnel syndrome (CTS) release open surgery of the of the right wrist in December 2021 that removed her CTS symptoms. Following the surgery, the patient experienced post-operative neuropathic symptoms. She suffered from two neuropathic pain conditions of the right hand: spontaneous pain — neuralgia and touch-evoked pain — SMA. She followed weekly, classical desensitization treatment to treat her neuropathic pain. Her neuropathic pain did not regress with treatment; she was told that her pain was part of her unforeseeable future.

After thirteen months of desensitization, the patient’s hand surgeon encouraged her to explore a different treatment option; she was referred to the Somatosensory Rehab Centre (Freiburg, Switzerland) in February 2023 to trial the method of Somatosensory Pain Rehabilitation (SPR).

This case report aims to illustrate the treatment of neuropathic pain of the hand with the method of SPR and its effectiveness.

Methods

Initial Evaluation

To evaluate the patient’s pain phenomena, the Certified Somatosensory Therapist of Pain (CSTP®) used the validated French version of the McGill Pain Questionnaire (MPQ) to assess the quality and intensity of the patient’s pain[16-17] (Table 1). MPQ remains the most used tool to assess pain intensity with good validity and reliability[18]. To describe her pain, the patient reported touch-evoked pricking and hot sensations on the palmar side of the right ulnar side of D3 and radial side of D4 —possible SMA. She identified the contact between her fingers and objects at work (e.g., mouse and pencil) as generating these painful sensations. In addition, she perceived tingling, numbness and spontaneous sensations of shooting along the proper palmar radial digital nerve of the median nerve —neuralgia.

To confirm a SMA diagnosis, the CSTP® used the Visual Analogue Scale (VAS) to identify the pain invariant, when the patient says “STOP”, which is defined as: pain at rest + 1 cm on a VAS[11]. Allodynography, a reliable and objective clinical examination sign of SMA[19], was performed to map the border of the cutaneous territory where the application of a 15 gram force (gf) (#5.18) stimulus on the skin generated a “STOP” response7,16. The 15gf stimulus is applied in 1-cm increments for 2 seconds starting distal to the painful area then proceeding longitudinally (proximal to distal), then transversely (medial to lateral and lateral to medial). In fact, the extent of SMA[20], thus the area of the SMA territory, may surpass the largest territory of cutaneous origin of one nerve branch[21]. With a positive allodynography and the patient’s report of intermittent spontaneous pain, the therapist named a condition: intermittent brachial neuralgia of the proper palmar radial digital nerve[2] (stage III of Aβ axonal lesions) with static mechanical allodynia. Based on this diagnosis, the certified therapist put in place treatment type B based on the algorithm of the method of SPR (Figure 2), as a SMA was present; the evaluation and treatment of touch-evoked pain (SMA) was necessary before the treatment of spontaneous pain (neuralgia) which requires tactile stimulation[16].

Table 1: Results of weekly assessments of somatosensory pain rehabilitation.

The CSTP® also employed a semi-structured interview to explore the patient’s pain experiences. Her occupations of work and leisure activities (e.g., painting and drawing) were most disrupted by her pain. The patient reported exhaustion from interrupted sleep; isolation and depression; a lost of self-confidence; and the incapacity of envisioning a future self. At the request of her therapist, the patient created an art piece representing her pain-filled life prior to starting treatment with the method of SPR (Figure 1).

Figure 1: Pre-treatment painting by the patient, right-handed, with her left hand.

Treatment goals

The treatment goals established with the patient were (1) to use her right hand without sensations of electricity, (2) to reduce her MPQ score to 20 and (3) to prevent a relapse of SMA.

Assessment and Treatment of Static Mechanical Allodynia

Following treatment type B (Figure 2), the certified therapist assessed and treated the SMA to remove touch-evoked needles and hot sensations. The severity of SMA was determined with the reliable clinical examination sign: Rainbow Pain Scale (RPS)[11,22] (Table 1). The RPS ranges from red to purple indicating a serious, consequential or discrete SMA[11]. The RPS is determined following the same guidelines of an allodynography. The patient’s initial severity of pain was green; the application of 1.5gf provoked pain.

The therapist prescribed Treatment B1 (Figure 2): to avoid tactile stimulation, if possible, on the allodynic territory[6]. The patient insisted on working 50% of her regular hours against her therapists’ recommendation. Her work tasks required prolonged tactile stimulation of her dominant hand (e.g., keyboard typing, writing, drawing and using a mouse). The therapists and the patient explored compensatory strategies to minimize the use of her dominant hand whilst maintaining participation in meaningful occupations. In addition, the patient was prescribed comfortable Distant Tactile Counter-Stimulation (DTCS): the application of low-level, non- noxious vibrotactile stimulation to related territories of normal sensations[6].

At each weekly sessions, the certified therapist reevaluated the allodynic territory to verify its reduction. For example, when the severity of the SMA was indigo, the CSTP® applied a 8.7gf filament on the most distal point of the territory and advanced proximally until the patient sayed “STOP”. Table 1 illustrates the evolution of the SMA territory, the RPS and the monthly MPQ score. Figure 3, the allodynography, represents the allodynic territory regression. The allodynography became negative once the application of 15gf no longer elicited a painful response after 294 days.

Assessment and Treatment of Neuralgia

Once the allodynic territory disappeared, a partial underlying hypo-aesthesia, presumed responsible for the patient’s spontaneous pain, was found. Searching for the tactile hypo- aesthesia was essential, as decreasing hypo-aesthesia decreases neuropathic pain[23]. This paradigm of the method of SPR is based on the adaptive neuroplasticity of the somatosensory system[24] which allows for the substitution of axonal lesions with axonal sprouting of neighboring, non-damaged nerves through repeated and precise tactile stimulation[23,25].

The CSTP® performed an underlying aesthesiography (Figure 2) to determine the territory where tactile stimulus was not detected (Figure 4). Unlike the extent of SMA[20, 21], an underlying hypo-aesthesia is always partial: its territory is ectopically circumscribed in a part of the largest territory of cutaneous origin of one nerve branch[2, 26].

Alternating weekly, the CSTP® performed the short-form Pressure Perception Threshold (PPT(S)) and short-form Pressure Perception Threshold (2PDTS) to quantify the importance of the hypo-aesthesia[6, 27, 28]. The PPT(s) determines the level of perception of the somatosensory cortical areas that are activated with tactile stimulation, ie., somatotopy. The clinician recorded the first aesthesiometer detected within the hypo-aesthesia in an Ascending (A) series. The PPT(S) score is the arithmetic average of the three forces detected during three Ascending series (AAA).

The 2PDT(S) determined the level of detection of tactile stimulation by the Brodmann area in the parietal occipital cortex[29]. It is not recommended to perform the 2PDT on an allodynic territory[30]. Therefore, the method of SPR utilizes the short-form 2PDT (2PDT(S)) to avoid tactile over-stimulation of the previous allodynic territory which can cause a SMA relapse. During the 2PDT(S), the clinician applied a 2-point caliper within the territory to determine the minimal distance between two points the patient could detect. The distance between the two points was progressively reduced as the patient successfully distinguished between one or two points. The CSTP® shifted from the PPT(S) and 2PDT(S) to the classical long version tests once the patient was able to stimulate the hypo-aesthetic territory for five minutes.

With a positive underlying aesthesiography, the patient is prescribed treatment B2 (Figure 2). The prescriptions of DTCS and avoiding tactile stimulation were maintained. In parallel, the patient progressively re-learned to perceive tactile stimulus with a modified somatosensory re-learning home program to prevent SMA relapse. Initially, the patient stimulated the hypoaesthetic territory with different textures recurringly and daily for a short duration (e.g., 15 seconds). Once shorter stimulations were well tolerated, the duration would increase weekly until five minutes of stimulations were comfortable.

Once her tactile hypo-aesthesia was normalized, The French version of the Disabilities of the Arm, Shoulder and Hand (DASH) Outcome Measure[31] to identify potential remaining disability experiences caused by her condition. The DASH could not be completed during the initial evaluation, as the patient was prescribed to avoid touching her pulps.

Results

The patient’s SMA of initial severity of green (the application of 1.5gf provokes pain) was resolved after nine months of treatment. The continuation of work by the patient during treatment prolonged the resolution of SMA. Subsequently, somatosensory re-learning decreased the patient’s underlying hypo-aesthesia which, consequently, decreased her spontaneous neuropathic pain (Table 1). She no longer detected spontaneous sensations of shooting. Low-intensity sensations of “burning” and “tingling” were seldom detected. Her MPQ score was below 20 points, decreasing to a range of 0-12 points from 10-57 points and confirming that her somesthetic situation had stabilized[6, 23]. The normalization of the underlying hypo-aesthesia (Table 1) on D4 confirmed the successful prevention of a SMA relapse. She stopped taking Pregabalin, a neuropathic pain medication. The French version of the (DASH) Outcome Measure31 score was 28/100 points.

The patient was able to complete full work days without discomfort. She shared her injury “forc[ed] [her] to follow a therapy that ultimately saved [her]”. She mentioned that prior to treatment, she was exhausted from enduring the pain exacerbated with work. She learnt to listen to what her body was communicating to her and to say STOP to herself and to others. The patient produced an artwork depicting her pain-free life following treatment of the method of SPR (Figure 5).

Figure 5: Post-treatment and pain-free painting.

Discussion

As a right-handed, 44-year-old graphic designer and artist whose right-hand use was necessary for work and leisure, the patient had undergone classical desensitization without any improvement of her neuropathic pain conditions. The patient’s touch-evoked pain –SMA and spontaneous pain –neuralgia of the proper palmar radial digital nerve D42 was resolved after thirteen months of treatment of the method of SPR.

As per Hebert and colleagues, a lack of consensus on the appropriate treatment of SMA15 remains given the equal level of evidence between desensitization, somatosensory relearning and counterstimulation. Similarly, an integrative review of non-pharmacological treatments for Complex Regional Pain Syndrome (CRPS), another neuropathic pain condition that can present with SMA, found the effectiveness of pain-provocation treatment (e.g., desensitization) in comparison to minimizing pain provocation (e.g., somatosensory relearning and counterstimulation) remains inconclusive32. The review highlights that avoidance of pain provocation can lead to protective behaviors and learned disuse of the affected limb[32]. Conversely, pain provocation can lead to flare ups[32]. The study’s finding aligns with the results of our study; for 13 months, the patient trialed desensitization, a pain provocation treatment consisting of stimulating the area where touch provoked pain, which increased her neuropathic pain symptoms. Additionally, a retrospective analysis of patients with CRPS of the foot found that somatosensory re-learning, a treatment based on avoidance of pain provocation, decreased neuropathic pain[26]. Similarly, the patient’s touch-evoked and spontaneous decreased with the implementation of the method of SPR, a treatment based on minimizing pain provocation, as shown in the progression of her MPQ score.

The modulation of patients’ pain response is based on past experiences[15]. Desensitization taught the patient to endure pain during activities. Experiencing more pain flare-ups, the patient was exhausted and ultimately not satisfied with her occupational participation33. In contrast, the method of SPR utilized pain avoidance. The patient learned how to say STOP, thus to respect the pain and avoid it, when the CSTP® performed evaluations. Her participation in occupations decreased which, alternatively, encouraged her to find compensatory strategies and set boundaries at work and at home. Ultimately, she had more energy to partake satisfyingly in her occupations which reduced her social isolation.

Finally, Griffiths and colleagues conclude that more studies including patient perspectives on intervention efficacy is needed[33]. Patient-therapist discussions about the efficacy of the recommended interventions are essential to ensure improvement of neuropathic pain conditions. Such discussions have the potential of increasing the implementation of patient empowerment by positioning the patient as the expert of their experience[34]. In fact, research suggests that discussions regarding patients’ intersectional identities, such as being disabled in the context of patients living with neuropathic pain, can positively contribute to therapeutic outcomes[35]. This case report illustrates that healthcare professionals should encourage feedback from their patients regarding their interventions and, consequently, trial a different treatment approach when the treatment implemented is not appropriate not efficient.

References

[1]    Finnerup NB, Haroutounian S, Kamerman P, et al. Neuropathic pain: an updated grading system for research and clinical practice. Pain 2016; 157(8): 1599–1606.

[2]    Spicher CJ, Packham TL, Buchet N, et al. Atlas of cutaneous branch territories for the diagnosis of neuropathic pain. 1st English ed. stemming from the previous 3rd French ed. Berlin, London, Shanghai, Tokyo, New-York City: Springer-Nature, 2020.

[3]    Valleix FLI. Traité des névralgies. 1e éd. Paris : J.B. Baillière & Fils, 1841.

[4]    Melzack R and Wall PD. The challenge of pain. Updated 2nd ed. London, England, New York: Penguin Books, 1996.

[5]    Bennett GJ. What is spontaneous pain and who has it? J Pain 2012; 13(10): 921-929.

[6]    Spicher C, Barquet O, Quintal I, et al. (2020) Douleurs neuropathiques : évaluation clinique & rééducation sensitive. 4e éd (translated in English as: Spicher CJ. Handbook for somatosensory rehabilitation. Montpellier, Paris: Sauramps medical, 2006.). Montpellier, Paris: Sauramps medical, 2006.

[7]    Bouchard S, Quintal I, Barquet O, et al. Douleurs neuropathiques : méthode d’évaluation clinique et de rééducation sensitive. Encyclopédie Médico-Chirurgicale (EMC) Kinésithérapie-Médecine physique-Réadaptation 2021; 9: 1-15.

[8]    Bouchard S, Quintal I, Barquet O, et al. Dolor neuropático: método de evaluación clínica y rehabilitación sensitiva. EMC, kinesiterapia – medicina física 2022; 44(1): 1-16.

[9]    Bouchard S, Quintal I, Barquet O, et al. Dolore neuropatico: metodo di valutazione clinica e di rieducazione sensitiva. EMC, medicina riabilitativa 2022; 9(1): 1-15.

[10]  Spicher C, Risch N, Osinski T, et al. De la nociception spécifique à la sensibilisation : théories et mécanismes des phénomènes inexpliqués de la douleur persistante. e-news Somatosens Rehab 2017; 14: 158-67.

[11]  Spicher CJ, Mathis F, Degrange B, et al. Static mechanical allodynia (SMA) is a paradoxical painful hypo-aesthesia: observations derived from neuropathic pain patients treated with somatosensory rehabilitation. Somatosens Mot Res 2008; 25: 77-92.

[12]  Sukhotinsky I, Ben-Dor E, Raber P, et al. Key role of the dorsal root ganglion in neuropathic tactile hypersensibility. Eur J Pain 2004; 8: 135-43.

[13]  International Association for the Study of Pain. Terminology, https://www.iasp- pain.org/resources/terminology/ (2011, accessed 26 August 2024).

[14]  Cervero F and Lair JMA. Mechanisms of touch-evoked pain (allodynia): a new model. Pain 1996; 68: 13-23.

[15]  Hebert A, MacDermid J, Harris J, et al. How should we treat painful sensitivity in the hand? An international e-delphi study. J Hand Ther 2023; 37(1): 12–21.

[16]  Boer K, Packham TL, Vögelin E, et al. Somatosensory rehabilitation of neuropathic pain. EZINE- IFSSH 2020; 39(3): 22-27.

[17]  Melzack R. The McGill pain questionnaire: major properties and scoring methods. Pain 1975; 1(3): 277-229.

[18]  Katz J and Melzack R. Measurement of pain. Surg Clin North Am 1999; 79: 231-52.

[19].  Packham TL, Spicher CJ, MacDermid JC, et al. Allodynography: reliability of a new procedure for objective clinical examination of static mechanical allodynia. Pain Med 2020; 21: 101-8.

[20]  Llewellyn A, Buckle L, Grieve S, et al. Delphi study to define core clinical outcomes for inclusion in a complex regional pain syndrome international research registry and data bank. Pain 2023; 164(3): 543–554.

[21]  Spicher CJ, Ribordy F, Mathis F. et al. L’allodynie mécanique masque une hypoesthésie : Observations topographiques de 23 patients douloureux neuropathiques chroniques. Doul & Analg 2008; 21: 239-251.

[22] Packham TL, Spicher CJ, MacDermid JC, et al. Evaluating a sensitive issue: reliability of a clinical evaluation for allodynia severity. Somatosens Mot Res 2020; 37: 22-7.

[23]  Spicher C and Clément-Favre S. Chronic neuropathic pain decreases through somatosensory rehabilitation. Recueil annuel d’ergothérapie 2008; 1: 25-33.

[24]  Hernández-Muela S, Mulas F and Mattos L. Plasticidad neuronal funcional. Revista de Neurologia

2004; 38(1Suppl.): S58-68.

[25]  Jerosch-Herold C. Sensory relearning in peripheral nerve disorders of the hand: a web-based survey and delphi consensus method. Journal of Hand Therapy: Official Journal of the American Society of Hand Therapists 2011; 24(4): 292–8.

[26]  De Andrade Melo Knaut S, Hoang MA, Bossard EK et al. Static mechanical allodynia is a paradoxical painful touch-evoked tactile hypo-aesthesia: a retrospective analysis of 86 patients with CRPS of the foot. Douleur et analg 2024; 37(2): 77-86.

[27]  Frey von, M. (1896). Untersuchung über die Sinnesfunktion der Menschlichen Haut: Erste Abhandlung: Druckempfindung und Schmerz. Des XXIII Bandes der Abhandlungen der mathematisch – physischen Classe der Königlichen Sächsischen Gesellschaft des Wis-senschaftes (pp. 175-266). Leipzig: S. Hirzel, III. (traduit en anglais sous: H.O. Handwerker & K. Brune (Eds.) [1987]. Classical German contributions to pain research (pp. 69-131).

[28]  Weber EH, (1834), De pulsu, resorptione, auditu et tactu. Leipzig, Koehler (Chapter translated in English as: Weber EH [1978] The sense of touch. Academic Press, London).

[29]  Pascual-Leone A, Amedi A, Fregni F, et al. The plastic human brain cortex. Annu Rev Neurosci 2005; 28: 377-401.

[30]  Jerosch-Herold, C. A study of the relative responsiveness of five sensibility tests for assessment of recovery after median nerve injury and repair. J Hand Surg Br 2003; 28(3): 255-260.

[31] The Disabilities of the Arm, Shoulder and Hand Outcome Measure. About the DASH, https://dash.iwh.on.ca/about-dash (accessed 26 August 2024).

[32]  Griffiths GS, Thompson BL, Snell DL et al. Person-centred management of upper limb complex regional pain syndrome: an integrative review of non-pharmacological treatment. Hand Therapy 2023; 28(1): 16–32.

[33]  Townsend EA and Polatajko HJ. Enabling occupation II: Advancing an occupational therapy vision for health, well-being, & justice through occupation. Ottawa: CAOT Publications ACE, 2007.

[34]  Harley DA, Jolivette K, McCormick K et al. Race, class, and gender: a constellation of positionalities with implications for counseling. Journal of multicultural Counseling and Development 2002; 30(4): 216-238.

[35]  PettyJohn, ME, Tseng CF and Blow AJ. Therapeutic utility of discussing therapist/client intersectionality in treatment: when and how? Family Process 2020); 59(2): 313–327.

[2] Masters of Sciences Applied MSc(A) in Occupational Therapy, CSTP®

[3] Somatosensory rehabilitation centre ; Clinique Générale ; 6, Hans-Geiler Street, Freiburg (Switzerland – Europe)

[4] CSTP®

[5] Medical Doctor (MD), Hand surgeon

[6] Certified Hand Therapist (CHT Switzerland) and McGill University lecturer claude.spicher@mcgill.ca