Difference in Response to a Motor Imagery Task: A Comparison between Individuals with and without Painful Temporomandibular Disorders

The Tongue and Mouth Imagery Questionnaire (TMIQ) for Assessing Motor Imagery vividness of the temporomandibular region: a reliability and validity case-control study

Background

To date, no validated assessment of motor imagery (MI) ability with temporomandibular disorders (TMD) exists preventing identification of good imagers and appropriate MI use during TMD rehabilitation.

Objective

To assess the reliability and construct validity of the previously developed Tongue and Mouth Imagery Questionnaire (TMIQ) compared with the gold‐standard Kinaesthetic and Visual Imagery Questionnaire (KVIQ‐10).

Methods

Both KVIQ‐10 and TMIQ assess MI ability using vividness (i.e. clarity/brightness for visual MI, _VMI; or intensity for kinesthetic MI, _KMI) of MI using a 5‐point Likert scale (1: no image/sensation, 5: clear/intense image/sensation). The KVIQ‐10 was administered once (test) and the TMIQ twice (test–retest) to heathy participants and patients with TMD. Questionnaire validity was investigated using concurrent validity (Pearson correlation and paired t test); TMIQ‐test–retest reliability (intraclass correlation coefficients, ICCs); internal consistency (Cronbach ⍺) and the factorial structure (principal factor extraction).

Results

A total of 94 participants were included (n = 47 per group). The mean vividness scores of the KVIQ‐10 and the TMIQ were significantly correlated, and not significantly different for both groups indicating concurrent validity. ICCs in the control group (range: 0.82‐0.90), and in the TMD group (range: 0.75‐0.82) indicated good reproducibility. The Cronbach ⍺ values were all above 0.94, indicating excellent reliability. Two factors were extracted corresponding to _VMI and _KMI, and explained 66% of total variance.

Conclusion

The TMIQ is a valid and reproducible MI questionnaire showing excellent internal consistency and, therefore, can be used to assess imagined movements of the TM region in healthy individuals and patients with TMD.

Body representation among adults with phantom limb pain: Results from a foot identification task

BACKGROUND

Impaired body representation (i.e. disrupted body awareness or perception) may be a critical, but understudied, factor underlying phantom limb pain (PLP). This cross-sectional study investigated whether adults with lower-limb loss (LLL) and PLP demonstrate impaired body representation as compared to Pain-Free peers with and without LLL.

METHODS

Participants (n = 41 adults with PLP, n = 27 Pain-Free peers with LLL, n = 39 Controls with intact limbs) completed an online foot identification task. Participants judged whether randomized images depicted left or right feet (i.e. left-right discrimination) as quickly as possible without limb movement. Using two Generalized Estimating Equations, effects of group, image characteristics (i.e. side, foot type, view, angle) and trial block (i.e. 1-4) were evaluated, with task response time and accuracy as dependent variables (a ≤ 0.050).

RESULTS

Adults with PLP demonstrated slower and less accurate performance as compared to Controls with intact limbs (p = 0.018) but performed similarly to Pain-Free peers with LLL (p = 0.394). Significant three-way interactions of group, view and angle indicated between-group differences were greatest for dorsal-view images, but smaller and angle-dependent for plantar-view images. While all groups demonstrated significant response time improvements across blocks, improvements were greatest among adults with PLP, who also reported significant reductions in pain intensity.

CONCLUSIONS

Adults with PLP demonstrate body representation impairments as compared to Controls with intact limbs. Body representation impairments, however, may not be unique to PLP, given similar performance between adults with and without PLP following LLL.

SIGNIFICANCE

Following lower-limb loss, adults with phantom limb pain (PLP) demonstrate impaired body representation as compared to Controls with intact limbs, evidenced by slower response times and reduced accuracy when completing a task requiring mental rotation. Importantly, 80% of participants with pre-task PLP reported reduced pain intensity during the task, providing compelling evidence for future investigations into whether imagery-based, mind-body interventions have positive effects on PLP.

Trigeminal neuralgia causes neurodegeneration in rats associated with upregulation of the CD95/CD95L pathway

Objectives

To explore the effects of trigeminal neuralgia on neurodegeneration in rats and the underlining mechanism.

Methods

Sixty adult male Sprague Dawley rats were divided randomly into Chronic Constriction Injury of the Rat’s Infraorbital Nerve (ION-CCI) group and sham group (n = 30). Right suborbital nerve was ligated in ION-CCI group to establish a trigeminal neuralgia model. In sham group, suborbital nerve was exposed without ligation. Pain thresholds were measured before surgery and 1, 7, 15, and 30 days after surgery (n = 10). Morris water maze tests (n = 10) were conducted at 1, 15, and 30 days after surgery to evaluate the changes in learning and memory ability of rats. At 5, 19, and 34 days after surgery, serum S100β protein concentration and hippocampal Aβ1-42 protein expression were detected by enzyme-linked immunosorbent assay; total tau protein expression was detected by Western blotting; changes of neurons in hippocampus were observed by Nissl staining; and the expression of ^ser404p-tau, cluster of differentiation (CD)95, CD95L, and cleaved caspase-3 proteins was detected by immunofluorescence and Western blotting.

Results

Hyperalgesia occurred in ION-CCI group, and mechanical pain threshold decreased significantly (P < 0.05). On the 15th and 30th days after surgery, ION-CCI group showed lower learning and memory ability than sham group (P < 0.05). Serum S100β protein concentration, hippocampal A β1-42, and ^ser404p-tau protein expression increased in the ION-CCI group 19 and 34 days after surgery (P < 0.05), hippocampal CD95 expression increased in the ION-CCI group after surgery (P < 0.05), hippocampal CD95L expression increased at 19 and 34 days after surgery (P < 0.05), and cleaved caspase-3 expression increased at 5 and 19 days after surgery (P < 0.05). Nissl bodies in ION-CCI group decreased significantly at 15 days after surgery. The expression of cleaved caspase-3 protein in ION-CCI group was positively correlated with the expression of CD95 and CD95L (P < 0.05).

Conclusions

Trigeminal neuralgia may lead to neuronal inflammation and neuronal apoptosis associated with upregulation of CD95/CD95L expression, thus causing neurodegeneration.

Temporomandibular disorders: improving outcomes using a multidisciplinary approach

Patients with temporomandibular disorders (TMD) can become very complex. This article aims to highlight the importance of the multimodal and multidisciplinary approach in this type of patients to improve clinical outcomes. At present we have innumerable techniques and tools to approach this type of patients from a biopsychosocial model where active and adaptive type treatments are fundamental. There are various health professions that have competence in the treatment of TMD, however, although in the most complex cases should be treated simultaneously, still too many patients receive unique treatments and only from one point of view. This review exposes the treatments available from a clinical-scientific perspective and also emphasizes the importance of working in specialized units with those professionals who have competencies on the different conditions that may occur.

Mental rotation of feet in individuals with Body Integrity Identity Disorder, lower-limb amputees, and normally-limbed controls

Body Integrity Identity Disorder (BIID) is a non-psychotic condition wherein individuals desire amputation or paralysis of one or more healthy, fully-functioning limbs (predominantly the legs). Individuals with BIID have been suggested to have a mismatch between the perceived mental representation of the body and its actual physical structure, such that their desired identity matches that of a lower-limb amputee. Accordingly, studies have reported an altered central network involving body representation of the legs in BIID, but its relationship to behavior remains unclear. In the present study, we investigated the integrity of body representation in individuals with BIID, acquired lower-limb amputees, and normally-limbed controls using an online mental rotation task. Participants judged the laterality of left and right foot images presented from different views, orientations, and of different types. We expected BIID participants to be slower for mentally rotating images that corresponded to their affected legs than lower-limb amputees and normally-limbed participants. We found that the groups did not significantly differ in their performance. All participants were slower at judging feet presented in awkward postures than natural postures, replicating previous studies and validating our online paradigm. The results are discussed in terms of the robust nature of visual and sensorimotor lower-limb representations, whether related to the self or as prototype, in the context of disturbed lower-limb integrity.