1.2.1

Patients

Twenty patients were consecutively included during their systematic check-up performed every 3 months. ALS was diagnosed according to El Escorial criteria (clinical and paraclinical criteria).

The swallowing clinical evaluation was carried out using the V-VST test.

The V-VST was performed only if the patient had an efficient cough, saturation higher than 92%, voluntary swallowing, was able to maintain attention for more than 15 minutes, and presented neither drooling nor wet voice . V-VST and videofluoroscopy were realized at the same time, by two different operators. The operator realizing the V-VST was unaware of the results of the pharyngography. During the whole duration of the test and of the videofluoroscopy, the oxy-hemoglobin saturation was measured by pulse oxymetry (Nellcor OxiMax N-560, Coviden, Boulder, USA).

The V-VST was realized by a physician or a trained technician. The test consisted in the administration of increasing volumes of different textures and the evaluation during each swallowing of the presence of signs of efficacy or safety alteration. The test starts with a nectar texture (prepared with 4.5 g of food thickener in 100 ml of mineral water) by bolus of increasing volumes of 5, 10, and then 20 ml. If the patients presented no sign of choking, the test was continued with a liquid texture by bolus of 5, 10, and then 20 ml. Finally, the test ended with a bolus of 5, 10, and then 20 ml of a pudding texture (prepared with 9 g of food thickener in 100 ml of mineral water) .

If the patients presented signs of alteration of safety with the nectar texture, the liquids were not tested, and the pudding texture was directly used. As for consistency, the volumes were not increased in case of safety alteration. The V-VST was assessed as abnormal as soon as the patient presented a clinical sign of safety alteration, i.e. laryngeal aspiration or tracheal penetration (cough, desaturation greater than 3%, or wet voice) or of efficacy alteration (presence of an oral or pharyngeal residue during swallowing, need for repeated swallowing, and presence of drooling) during a single swallowing ( Fig. 2 ).

1.2.2

Videofluoroscopic evaluation of swallowing

Swallowing was assessed by videofluoroscopy to determine the presence or not of oropharyngeal dysphagia. Acquisition of images was realized by image intensifier (Flexiview 8800, General Electric, United Medical Technlogies Corp., Fort Myers, FL, USA) and was recorded on a computer at 20 images per second (MMS, Tubingen, The Netherlands). The upper incisors, the higher part of the palate, the upper cervical spine, and the lower part of the proximal esophagus were included in the field of projection.

The patients were comfortably seated in an armchair and were asked not to move during the video recording. They swallowed three barium boluses of respectively 5, 10, and 20 ml of nectar, then liquid, then pudding texture, following the same procedures of realization as those of V-VST. All boluses were measured with a 20-ml syringe and then given either in a glass or with a spoon.

Food choke was quantified through a validated 8-point scale . The diameter of a 5-centimes coin was used as a marker to assess the pharyngeal stasis and allowed its rating using a 5-point scale: 0 was absence of stasis whereas 4 was major stasis . The alterations of oral timing were also recorded by a 5-point score where 0 corresponded to the absence of temporal alteration, and 4 to the impossibility to control bolus formation . This reference examination enabled us to diagnose the presence of oropharyngeal dysphagia in case of stasis, food choking and temporal alteration.

1.2.3

Evaluation of nutritional status

The patients were weighed, which allowed calculating their body mass index (BMI). This enabled the assessment of undernourishment.

1.2.4

Norris bulbar scores and Amyotrophic Lateral Sclerosis Funtional Rating Scale (ALSFRS)

The bulbar Norris score allowed orienting towards a bulbar form of ALS. It was scored from 39 (normal status) to 0 (total dysfunction of bulbar form) . The ALSFRS score was used to assess the functional disability, taking into account 10 activities of daily life noted on five points each, where 0 corresponded to “impossibility to do it” and 4 to “normal activity” .

1.2.5

Statistics

The patients were divided in two groups: one group of patients presenting oropharyngeal dysphagia, and one group with normal swallowing, according to the results of the videofluoroscopy. The results of the V-VST were then analysed as being normal or abnormal (safety or efficacy altered). Sensibility and specificity of the V-VST for the diagnosis of oropharyngeal dysphagia were calculated using a test of the Chi ² (StatView 5, SAS Institute, Cary, NC, USA).

The Norris and ALSFRS scores were analysed and compared between groups with the non parametric test of Mann-Whitney (StatView 5, SAS Institute, Cary, NC, USA). The differences were considered as significant if P ≤ 0.05.