PATIENTS AND METHODS

Patient selection

Thirty-six patients, diagnosed as having MSA at the Department of Neurology in our institute, from 1996–2001, were included in this study. Thirty-three patients were probable MSA, two were possible MSA, and the other one was definite MSA, according to Gilman’s criteria.⁷ They consisted of 21 males, of ages from 53–78 years (average 62.1 years), and 15 females, of ages from 46–82 years (average 62.5 years). Twenty-eight of the 36 patients had MSA-C, and the other 8 had MSA-P. Informed consent was obtained from each patient, and the local ethics committee approved this study.

Laryngeal endoscopy and videofluoroscopy for assessment of VFMI and swallowing function

VFMI was evaluated by laryngeal endoscopy for each patient. Swallowing function was investigated by videofluoroscopy (VF). The assessment parameters in pharyngeal swallowing on VF examination were as follows: constriction of the pharynx, tongue base movement, elevation of the larynx, bolus stasis at the pyriform sinus (PS), the upper oesophageal sphincter (UOS) opening, and aspiration. A 3 point scale: 0 (normal), 1 (disturbed), and 2 (severely disturbed), was used to quantify each parameter, and for statistical analysis.

Severity stages of the disease

Severity stages of the disease were used as an assessment parameter. According to Watanabe et al,⁸ severity stages of the disease were determined as follows:

• Stage 1: Able to walk without support.

• Stage 2: Aid-required walking, with use of a walking aid or a companion’s arm for support, but not at all times.

• Stage 3: Aid-required walking, with use, at all times, of a walking aid or a companion’s arm for support.

• Stage 4: Wheelchair-bound state (wheelchair use at all times).

• Stage 5: Bedridden state (complete loss of ability for independent activity).

Statistical analysis

Relationships between VFMI and assessment parameters in pharyngeal swallowing on VF examination were analysed using Spearman’s rank correlation. The Mann-Whitney U test was used to determine differences for age, duration of disease, and severity stages of the disease. Statistical significance was defined as p<0.05.

RESULTS

Laryngeal endoscopy

VFMI was found in 17 patients (47.2%). Fourteen of 17 patients had moderate or severe bilateral abductor paralysis of the vocal folds, and three of the 14 had received a tracheotomy. Two of 17 patients showed unilateral vocal fold fixation. The other patient showed bilateral vocal folds fixation at the paramedian position. Patients were divided into two groups according to having VFMI (Group VFMI+) or not (Group VFMI−). In Group VFMI−, 15 patients had MSA-C, and four had MSA-P; in Group VFMI+, 14 patients had MSA-C, and three had MSA-P. The duration of disease ranged from 1–16 years (average 5.0 years) in Group VFMI−, and from 2–10 years (average 5.4 years) in Group VFMI+.

There were no significant differences in duration of disease or age between Group VFMI− and VFMI+. Severity stages of the disease were different between Group VFMI− and VFMI+ (fig 1). The ratio of patients in advanced severity stages of the disease was significantly higher in Group VFMI+ compared with Group VFMI− (Mann-Whitney U test; p=0.0479).

Videofluoroscopic evaluation

Dysfunction of tongue base movement was the most common disturbance seen in 36 MSA patients, followed by disturbed elevation of the larynx (table 1). Aspiration was seen in 21.1% of Group VFMI− and 29.4% of Group VFMI+. Among various parameters, bolus stasis at the PS and UOS opening tended to be more disturbed in Group VFMI+ than in Group VFMI−; however, Spearman’s rank correlation did not show significant differences in pharyngeal swallowing function between Groups VFMI− and VFMI+.

Nutrition status of tracheotomised patients

Three patients, who underwent a tracheotomy, could eat orally before the tracheotomy. The first patient could not eat orally, resulting in tube feeding right after the tracheotomy. The second patient could eat orally even after the tracheotomy in the hospital. After discharge, the patient still could eat orally to some degree; however, tube feeding to ingest sufficient nutrition was needed. The last patient maintained oral feeding for four months after the tracheotomy, but aspiration pneumonia occurred several times, and a laryngectomy ultimately had to be performed.

DISCUSSION

MSA is considered to be a parkinsonian disorder. VFMI is also seen in Parkinson’s disease (PD); however, VFMI in PD is different in several aspects from that in MSA.^1,9 Firstly, VFMI is infrequently seen in PD, compared with MSA. Secondly, VFMI in PD is usually seen during both sleep and the daytime, while VFMI in MSA is predominant during sleep and extends to the daytime as the disease progresses. Thirdly, no abnormalities of the intrinsic laryngeal muscles were found in PD, while selective neurogenic atrophy of the posterior cricoarytenoid muscle was characteristic in MSA.^1,2

Dysphagia, as well as VFMI, is a serious complication in both MSA and PD. As to swallowing function in PD patients with VFMI, a close relationship between VFMI and dysphagia has been reported. Isozaki et al reported that PD patients with VFMI had severe dysphagia requiring tube feeding.¹ A similar tendency was also found in other reports.^9–11 However, swallowing function in PD patients with VFMI was not systematically evaluated in these reports by VF or videoendoscopy.

Swallowing function in MSA has not been explored systematically, either. We evaluated swallowing function in MSA patients with and without VFMI by VF examination, and found a tendency for UOS opening and bolus stasis at the PS to seem more involved in Group VFMI+ than in Group VFMI−. Bolus stasis at the PS is supposed to be closely related to dysfunction of the thyropharyngeal muscle (a constrictor of the pharynx), and disturbance of UOS opening is supposed to be related to dysfunction of the cricopharyngeal muscle (a sphincter of the upper oesophagus). Since both the thyropharyngeal and cricopharyngeal muscles, as well as the intrinsic laryngeal muscles, are innervated by the vagus nerve, a close relationship between dysfunction of swallowing and vocal fold motion is suspected; however, our results did not show significant relationships between pharyngeal swallowing dysfunction and VFMI in MSA. MSA patients with VFMI do not always suffer from worse dysphagia compared with those without VFMI.

A tracheotomy, especially with use of a cuffed tracheotomy tube, negatively influences swallowing. Mechanisms of swallowing disturbance caused by a cuffed tracheotomy tube are considered as follows: (1) a cuffed tracheotomy tube disturbs elevation of the larynx; (2) a cuff that presses the oesophagus disturbs a bolus passing through the esophagus; (3) subglottic pressure is lost, and a bolus is susceptible to penetrate into the glottis. In this study, three patients ultimately required tube feeding or a laryngectomy after the tracheotomy. Since they received no other intervention besides a tracheotomy, the tracheotomy seems to directly affect swallowing function in these patients; however, another factor should be also taken into consideration.

Kurisaki commented that activity of daily life of MSA patients becomes rapidly worse after a tracheotomy.¹² He discussed that this phenomenon resulted from progress of the disease. In our study, severity stages of the disease were worse in Group VFMI+ compared with Group VFMI−. These facts suggest that appearance of VFMI is a sign of disease progression, and the disease has almost already progressed to the status of requiring tube feeding, by the time MSA patients need a tracheotomy. The timing of a tracheotomy might be a kind of MSA-specific borderline between oral and tube feeding.

Isozaki et al found that almost half of patients could take all nutrition orally even after VFMI was identified, in MSA,⁴ and our results also showed that there were no significant differences in swallowing function of MSA patients between with and without VFMI. As such, unnecessary “prophylactic” tube feeding for MSA patients with VFMI, out of fear of aspiration pneumonia, should be avoided; however, MSA patients who undergo a tracheotomy frequently require tube feeding. Appropriate evaluation and treatment for VFMI and dysphagia during follow ups, especially to judge indications for a tracheotomy and to introduce tube feeding, are important for patients’ quality of life.