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Mouth opening and trismus in patients undergoing curative treatment for head and neck cancer

Mouth opening and trismus in patients undergoing curative treatment for head and neck cancer



International Journal of Oral & Maxillofacial Surgery, 2015-03-01, Volume 44, Issue 3, Pages 292-296, Copyright © 2014 International Association of Oral and Maxillofacial Surgeons


Abstract

This study documents mouth opening and the incidence of and factors contributing to trismus (<35 mm mouth opening), as well as the associated impact on quality of life, following curative treatment for head and neck cancer. Patient demographics, cancer type and location, and treatments were documented. Mouth opening was measured at >6 months after treatment completion. Patients rated the impact of mouth opening on quality of life from 0 (no effect) to 10 (greatest effect). The mean mouth opening in 120 patients was 40.1 mm (range 11–65 mm), with trismus occurring in 34 (28.3%) patients. Surgery and radiotherapy, surgery and chemoradiotherapy, and resection and reconstruction were associated with reduced mouth opening. The mean effect of mouth opening on quality of life for those with and without trismus was 3.8 and 1.5, respectively. There was a significant difference between the mean effect on quality of life for patients with and without trismus for those patients who underwent chemoradiotherapy or combined surgery and radiotherapy (4.0 vs. 1.0, and 3.6 vs. 1.6 respectively). Trismus impacts negatively on patient quality of life. Multi-modality treatment is associated with decreased mouth opening, an increased incidence of trismus, and reduced quality of life.

Head and neck cancer (HNC) was the eighth leading cause of cancer deaths in 2000 and the seventh leading cause in 2004. The majority of HNC cases require combined treatment with surgery and/or radiotherapy (RT) and/or chemotherapy (ChT).

Trismus is defined as a progressive tonic contraction of the muscles of mastication that results in decreased mouth opening. Factors that contribute to the development of trismus include trauma, infection, drugs (e.g. succinyl choline, phenothiazines, and tricyclic antidepressants), direct tumour invasion of the masticatory muscles and/or temporomandibular joint, submucosal fibrosis, and RT and/or ChT. Trismus can lead to impairment of speech and eating, malnutrition, poor oral hygiene, and difficulty with dental treatment. Severe trismus can cause difficulties with examination of and surgical access to the oral cavity and oropharynx and difficulties with intubation.

Trismus is a well-recognized complication of treatment for HNC with a reported incidence of 5–86%, depending on the study and its definition of trismus. The absence of a consistent definition of trismus and method of measuring mouth opening makes it difficult to compare research results. However, mouth opening of <35 mm has been used to define trismus in several studies. Few studies have addressed the impact of mouth opening on quality of life (QoL), and these have yielded inconsistent findings.

Materials and methods

Consecutive patients who underwent treatment for HNC with curative intent between 1 January 2009 and 1 June 2012 were identified from HNC databases at three New Zealand hospitals. Following ethical approval by the internal review boards of the three respective district health boards, the data of these patients were merged into a single database. Patients were assessed in multidisciplinary head and neck clinics and all underwent surgery and/or RT or chemoradiotherapy (CRT). They were categorized into three groups: those with primary tumours located in (1) the oral cavity, (2) the oropharynx or nasopharynx, or (3) the parotid gland, or metastatic disease in the parotid and/or neck from a skin cancer or an unknown primary. Patients were excluded from the study if they had died, had recurrent disease during the study period, had an unrelated jaw fracture, had submucosal fibrosis, moved overseas, were incarcerated, or declined participation. Patient demographics, tumour type, stage and location, presence of regional metastasis, and treatment regime were documented. Data were supplemented by review of the patient medical records.

All patients were staged using the TNM staging system following clinical and radiological assessment. They were treated with surgery and/or RT or CRT. Patients with primary cancer located in the oral cavity were more likely to undergo surgical resection (with or without adjuvant RT ± ChT), whereas those with oropharyngeal or nasopharyngeal cancer mostly received RT usually combined with ChT. Of the patients who underwent surgery, those with less extensive disease generally underwent resection alone, whilst those with more extensive disease underwent resection and reconstruction.

All patients receiving RT were treated with three-dimensional conformal RT or intensity modulated RT (IMRT). ChT was used together with RT either as a primary treatment or in adjuvant settings after surgery.

Patients were followed up routinely in outpatient clinics and were assessed for recurrence clinically and, if indicated, radiologically. Patients with tumour recurrence during the study period were excluded.

In order to assess the mouth opening experienced by the patients on a day-to-day basis, mouth opening was measured as the distance between the upper and lower incisors in dentate patients, or between the maxillary and mandibular alveolar ridges in edentulous patients who did not wear dentures, using a TheraBite Range of Motion Scale. Patients who wore dentures were measured with their dentures in situ. Trismus was defined as mouth opening of <35 mm, whilst severe trismus was defined as mouth opening of <25 mm. Patients completed a questionnaire assessing the impact of mouth opening on QoL, using a visual analogue scale from 0 (no effect) to 10 (greatest effect). All non-responders at 2 weeks were followed up by phone.

The statistical analysis was performed using the Student's t -test for independent variables.

Results

Two hundred and fifty-nine patients were identified for inclusion in the study. Patients were excluded if they had died ( n = 94), developed recurrence during the study period ( n = 10), had an unrelated jaw fracture ( n = 1), moved overseas or were lost to follow-up ( n = 5), were incarcerated ( n = 1), were deemed unable to give informed consent to participate ( n = 1), or did not consent to participate ( n = 27). Our final study population was 120 patients; 43 were females and 77 were males, and they ranged in age from 34 to 87 years (mean 63.7 years) ( Table 1 ). The locations of the primary tumours are shown in Table 1 . Due to small numbers of tumours at each sub-site, they were categorized into three groups based on anatomical proximity and likely method of treatment. The tumours were located in the oral cavity ( n = 45), oropharynx or nasopharynx ( n = 35), and parotid gland, or metastatic disease in the parotid and/or neck from a skin cancer or an unknown primary ( n = 40).

Table 1
Patient demographics and location of primary tumours.
Total no. of patients No. of patients with trismus a (%)
Sex
Male 77 20 (26.0)
Female 43 14 (32.6)
Tumour location
Oral cavity 45 10 (22.2)
Nasopharynx 2 2 (100.0)
Oropharynx 33 11 (33.3)
Parotid 6 0
Metastatic disease to parotid and/or neck from skin cancer 25 10 (40.0)
Metastatic disease to parotid and/or neck from unknown primary 9 1 (11.1)
Dental status
Incisor b –incisor 93 27 (29.0)
Incisor b –alveolar ridge 15 5 (33.3)
Alveolar ridge–alveolar ridge 12 2 (16.7)

a Defined as mouth opening of <35 mm.

b Incisor of the native dentition or that of the denture.

Patients were treated with surgery alone ( n = 18, 15%), surgery with postoperative adjuvant RT ( n = 56, 46.7%), surgery with postoperative adjuvant CRT ( n = 7, 5.8%), primary CRT ( n = 34, 28.3%), or RT alone ( n = 5, 4.2%). The mean follow-up period between completion of treatment and the measurement of mouth opening was 709.7 days (standard error of the mean 31.67, median 654, standard deviation 34.5 days).

All patients who completed the questionnaire had their mouth opening measured; mean mouth opening was 40.1 mm (range 11–65 mm). Trismus was identified in 34 (28.3%) patients, with four (3.3%) classified as having severe trismus (mouth opening < 25 mm). The dental status of the patients is shown in Table 1 .

Trismus occurred in 10 (22.2%) patients with cancer in the oral cavity, 13 (37.1%) patients with cancer in the nasopharynx or oropharynx, and 11 (27.5%) patients with primary parotid cancer, or metastatic disease in the parotid and/or neck from skin cancer or an unknown primary ( Table 2 ). These patients had a mean mouth opening of 40.5 mm, 38.5 mm, and 40.2 mm, respectively. The mean effect of mouth opening on QoL was 2.8, 2.8, and 2.2, respectively. These differences in mouth opening and its effect on QoL were not statistically significant.

Table 2
The effect of site of cancer on mouth opening.
Location of cancer Total No. of patients No. of patients with trismus a (%) Mean jaw opening, mm (SEM) Mean effect on QoL b (SEM)
No trismus Trismus No trismus Trismus
Oral cavity 45 10 (22.2%) 46.4 (1.33) 27.3 (2.34) 1.51 (0.37) 3.50 (1.19)
Nasopharynx or oropharynx 35 13 (37.1%) 43.3 (1.33) 28.2 (1.72) 0.86 (0.32) 4.85 (0.84)
Parotid, skin or unknown primary with metastasis 40 11 (27.5%) 44.0 (1.08) 30.8 (0.98) 1.93 (0.73) 2.91 (0.42)
SEM, standard error of the mean; QoL, quality of life.

a Trismus is defined as mouth opening of <35 mm.

b Assessed using a visual analogue scale from 0 (no effect) to 10 (greatest effect).

The difference in the effect of RT alone on mouth opening was not statistically significant compared with that of surgery alone (surgery alone vs. RT alone; P = 0.44). However, the effects of some treatments on mouth opening were statistically significant: surgery alone vs. surgery and RT ( P = 0.04); surgery alone vs. surgery and CRT ( P = 0.046); resection alone vs. resection and reconstruction ( P = 0.019). For all treatment types, except for surgery when combined with RT and ChT, there was a significant difference between the mean mouth opening for those with and without trismus ( Table 3 ).

Table 3
The effect of treatment on mouth opening and quality of life.
Treatment received No. of patients (%) No. of patients with trismus a (%) Mean mouth opening, mm Mean mouth opening, mm (SEM) P -value b Mean effect on QoL (SEM) P -value b
Trismus No trismus Trismus No trismus
All patients 120 (100.0) 34 (28.3) 40.1 28.6 (0.99) 44.8 (0.74) <0.00 * 3.8 (0.53) 1.5 (0.22) <0.00 *
S 18 (15.0) 3 (16.7) 45.5 30.8 48.4 0.7 1.7
RT 5 (4.2) 0 (0) 41.0 43.0 2.0
RT + ChT 34 (28.3) 10 (29.4) 41.3 30.5 (0.76) 44.9 (1.50) <0.00 * 4.0 (0.68) 1.0 (0.34) <0.00 *
S + RT 56 (46.7) 19 (33.9) 38.0 27.4 (1.67) 43.7 (0.88) <0.00 * 3.6 (0.73) 1.6 (0.31) 0.03 *
S + RT +ChT 7 (5.8) 2 (28.6) 37.9 27.0 42.2 9.5 2.2
Resection alone 45 (55.6) 13 (28.9) 40.7 28.9 45.7 <0.00 * 3.6 (0.99) 1.8 (0.42) 0.10
Resection + reconstruction 36 (44.4) 11 (30.6) 38.7 26.5 44.0 <0.000 * 3.8 (1.06) 1.4 (0.40) 0.05
SEM, standard error of the mean; QoL, quality of life; S, surgery; RT, radiotherapy; ChT, chemotherapy.

a Trismus is defined as mouth opening of <35 mm.

b Two-tailed P -value.

* Statistically significant differences.

The mean effect of mouth opening on QoL was 1.5 in those without trismus, compared to 3.8 in those with trismus ( P < 0.000) ( Table 3 ). For those with severe trismus (mouth opening < 25 mm), the effect on QoL was 6.5 compared to 3.5 in those with moderate trismus (mouth opening 25–34 mm) ( P = 0.03). A significant difference between the mean effect on QoL for patients with and without trismus was found for those patients who underwent combined RT and ChT or combined surgery and RT ( Table 3 ).

The relationship between the extent of the cancer (as determined by the TNM staging system) and the development of trismus was not statistically significant (data not shown).

Discussion

Trismus is a well-recognized complication of treatment for HNC, with a reported incidence of 5–86%. Defining trismus as mouth opening <35 mm, we found an overall incidence of 28.3% in a cross-section of patients undergoing curative treatment for HNC. Multi-modality treatment is associated with decreased mouth opening. Patients who receive CRT, or combined surgery and RT, have decreased mouth opening and a higher incidence of trismus when compared to those who receive single-modality treatment with surgery or RT. For those patients who received surgery, RT, and ChT combined, the difference in mean mouth opening between those with and without trismus was not shown to be statistically significant in this study. There was also no statistically significant difference between the effect on QoL for those with and without trismus in patients undergoing this treatment regime. However, this may reflect the small population size.

For patients undergoing surgery, the decreased mouth opening for those receiving resection and reconstruction surgery, compared to those who had resection surgery alone, is most likely to reflect the extent of the cancer in the former group.

The negative impact of trismus on patient QoL is not unexpected, considering its effect on speech, nutrition, and oral hygiene. The negative impact of multi-modality treatment on QoL may result from the cumulative adverse effects of the treatments required, reflecting the extent of the disease. However, few studies have addressed the impact of mouth opening on QoL, and these have yielded inconsistent findings. A study of 40 patients receiving RT with/without ChT for HNC showed decreased QoL for patients with trismus, while another study showed a weak correlation between limited mouth opening and decreased QoL.

A positive association between the tumour stage and the incidence of trismus has been reported in a previous study. However, our study did not demonstrate a significant correlation, possibly due to our small sample size. We could also find no association between mouth opening and the site of the primary tumour.

There are several limitations in this study. First, no pre-treatment data on mouth opening were collected, which limits the assessment of the impact of treatment on the incidence of trismus compared to the possibility of pre-existing trismus. A consecutive cross-section of patients undergoing curative treatment for HNC was included to minimize selection bias and to ensure treatment modalities remained as consistent over time as possible. Furthermore, a multivariate analysis could not be performed due to the small sample size. These two limitations prevent the evaluation of the extent that the tumour itself versus the treatment administered contributes to the development of trismus.

It has been postulated that radiation-induced trismus results from scarring of the pterygomandibular raphes, and fibrosis and contracture of the ligaments surrounding the temporomandibular joint. The abnormal proliferation of fibroblasts may contribute to the development of fibrosis. In addition to atypical fibroblasts, the presence of infiltrative inflammatory cells and different extracellular matrix components has been noted in post-radiation fibrosis. The inclusion of the pterygoid muscles, masseter muscle, or temporomandibular joint in the radiation field has been considered to be the main cause of trismus. The severity of trismus is related to the field and dose of RT, with doses above 70 Gy being associated with a greater reduction in mouth opening. One study noted an increase in the probability of trismus by 24% for every additional 10 Gy above 40 Gy, to the pterygoid muscle. Trismus has been shown in two publications to start 9 weeks after the completion of RT, with subsequent rapid progression over the next 9 months, and then slowing.

Surgery involving the buccal mucosa, tonsillar fossa, and retromolar trigone area has also been shown to cause trismus, which has been attributed to fibrosis and shortening of the pterygoid muscle and pterygomandibular ligament.

Trismus often develops soon after treatment, highlighting the need for early follow-up and intervention for the patients. Delayed treatment may lead to a more difficult recovery due to secondary changes in the joints and muscles. Several treatment methods for trismus have been proposed, including manual stretching, jacking with tongue depressors, Therabite, the Dynasplint Trismus System, and pentoxifylline administration. However, the long-term effectiveness of these techniques has not been studied adequately and further research is needed.

We have demonstrated that trismus is a significant problem; it affected 28% of a cross-section of patients undergoing curative treatment for HNC. This study shows that combined modality treatment is associated with a higher incidence of trismus and that trismus is associated with poorer QoL. Although in this study the patients were requested specifically to rate the effect of mouth opening on their QoL, our findings could, in part, be a reflection of the negative impact of increased morbidity that is commonly associated with multi-modality treatment. Future studies should aim to determine to what extent increased morbidity contributes to the deterioration in QoL. Further research is required to fully understand the pathogenesis of trismus. Advances in trismus prevention and treatment are also needed to reduce morbidity and improve the QoL of HNC patients.

Funding

None.

Competing interests

None.

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