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Respiratory dysfunction in Multiple Sclerosis-Evaluation and Treatment


Guy Ganty
Principle Speech Therapist, Rehabilitation Center, National Multiple Sclerosis Center,Melsbroek,Belgium





Summary
Respiratory treatment for people with MS is often inconsistent and starts too late, when the lungs present a congestive aspect or when communication and swallowing disorders are well established. Special attention must be given to the early pulmonary restrictive syndrome, which appears generally when people with MS become dependant on the wheelchair. Routine pulmonary function testing may easily determine the most suitable therapy. Early multidisciplinary treatment which includes muscular respiratory training eventually completed by a non-invasive ventilation is indicated. It should prevent people with MS from the risks of bronchopneumonia, aspirations, restricted communication, intubation and tracheostomy, with their usual complications.

Introduction
Literature often describes the terminal stages of respiratory disorders in MS or the lethal conclusion of 8 percent of people with MS showing bulbar lesions. Because of the small functional impact of these progressive disorders during the early stages, little attention is given to the progressive restrictive aspect of respiratory disease. Treatment usually starts too late, when the patient presents with a combined or obstructive profile. Only an early assessment and a continuous treatment, which is non-invasive and minimally tiring may efficiently prevent people with MS from future restrictive, obstructive or mixed pulmonary disorders.
Our daily experience with people with MS for more than 20 years shows that this early intervention is efficient. It is certainly complex, due to the multiplicity of lesions and secondary systemic factors, such asaspiration or pneumonia which, in addition to tiredness, are the most important factors. Treatment must be continuous and focused on pulmonary function as well as vocal and swallowing rehabilitation. It requires a multi- disciplinary team. Motivation is very high: 48% of patients ask spontaneously for a daily respiratory treatment.
Patterns of respiratory dysfunction
Early respiratory involvement may be due to the following circumstances:
   Reversible respiratory failure due to demyelinating lesions of the cervical spinal cord or of the respiratory centers in the medulla including apnea or altered ventilatory patterns such as failure of voluntary respirations with preservation of automatic respiratory function
   Reversible and even relapsing hemidiaphragmatic paralysis and bilateral diaphragm weakness due to involvement of the cervical spinal cord
   Weakness of the respiratory muscles, generally due to quadriparesis or bilateral arm weakness, causing restrictive lung functioning
   During the last decade, some studies have suggested that occult respiratory muscle weakness may be found in people with MS free from pulmonary symptoms
Respiratory motoneurons originating in the ventral respiratory group cross the ventral and lateral medulla to innervate the phrenic, intercostal and abdominal muscles. Therefore, since motoneurons to respiratory and extremity muscles lie in close proximity in the brain stem and cervical spinal cord, there should be some correlation between motor weakness found on the general neurologic examination and respiratory muscle weakness. So, respiratory involvement may occur early in the course of the disease, particularly during relapse, and contributes to the occurrence of voice disorders such as decreased loudness and phonasthenia. It will also contribute to progressive congestion of the lungs and increase the risks of suffocation in case of dysphagia.
In summary, during this evolution, people with MS will progressively present a restrictive syndrome and develop progressive congestion of the lung bases. The position in the wheelchair, bed confinement, tobacco use, dysphagia and drugs, reinforce the primary patterns. For these reasons, sustained treatment which combines muscular training and ventilatory support should initiated early to preserve pulmonary function and communication in patients who develop these problems.
Early clinical routine assessment
Because muscular weakness (Figure 1) is invariably present in patients who experience difficulty in coughing or in removing airway secretions or in those with upper arm weakness, (but also because the weakness may probably be present in other cases as well), assessment of respiratory function must be a component of the routine examination.
In daily practice patients may be interviewed for history of respiratory illness, tobacco use, pulmonary and bulbar symptoms and questioned about the ability to clear secretions. The degree of weakness of respiratory muscles and the possible presence of cerebellar signs are evaluated (tremor, quavering voice). The usual positions in bed or in a wheelchair and the patient’s daily behavior require consideration from the practitioner. Assessment must be completed by pulmonary function measurements including lung volume, flow rates, peak flow rates, maximal voluntary ventilation and oxygen saturation. The practitioner will take into account the tiredness of the patient during testing; the "best effort" will be the only score considered for analysis.
Radiological imagery completes the evaluation and provides information about the mechanical aspects of ventilation and the grade of lung congestion.
Figure 1: Consequences of muscular weakness in MS
Treatment
Treatment of pulmonary disorders is best managed by a multidisciplinary team:
   physician,
   nurse,
   physiotherapist,
   occupational therapist and
   speech therapist.
From the beginning, special attention must be given to the maintenance of thoracic and pulmonary compliance. This basic philosophy would become spontaneous by the physiotherapist.
1. Preventive Respiratory Training
The following exercises should be principally performed during the first stages of MS, before appearance of any reduction of respiratory parameters:
   Training of trunk stability (abdominal muscles)
   Exercises geared on proprioception
   Learning of physiological breathing (dissociation of costal and abdominal breathing)
   Training of active and activo-passive mobility of thorax and spine
   Exercises of self- elongation of the spine
   Respiratory postures
   Breathing guidance at low and high volumes
   Diaphragmatic training under visual control
   Techniques of relaxation
2. Criteria for Specific Treatment
The treatment must start as soon as possible when:
   Index of Pulmonary Dysfunction in MS (Figure 2) is greater than 6
   Reduction of vital capacity is greater than 40 %
   Patient presents with a reduction of expiratory flow rate
   Patient presents with a reduction of maximal voluntary ventilation
   Radiological imagery shows a congestive aspect
   Patient presents with voice disorders
   Patient presents with sporadic or severe dysphagia
  
Patient’s rating
1.
Difficulty handing mucus/secretions No 1
Yes 2
2.
Cough: patient’s rates as normal or weak/diminished in strength Normal 1
Weak 2
Examiner’s rating
3.
Strength of patient’s cough when asked to cough voluntarily as forcefully as possible Normal 1
Weak 2
Very Weak 3
4.
Value reached when patient count aloud on a single exhalation after maximum inspiratory effort 30 1
20 - 29 2
10 - 19 3
<10 4
Summed Score:
Figure 2 - Index of Pulmonary Dysfunction in MS (London 1976)
Because of the multiplicity of pathological profiles, treatment must be combined and adapted to each patient. If possible, treatment must be applied daily, not tiring, preferably twice a day.
Correction of position and adaptation of the wheelchair
First of all, position in the wheelchair must be correct when the stability of trunk and head is reduced. Adapted head rests, molded seat, lumbar support, can be useful but must surely not limit the compliance.
Mobilization of shoulders, thorax and upper limbs
All techniques of the preventive training may be adapted according to the grade of muscular tone and weakness and are surely the foundations of the therapy. Active or passive reverse pedaling may be used.
Active training of inhalation and exhalation phases
Devices such as InspirX, Triflo, Respirex, Volurex or peak flow meters, spirometers, blow- bottles may complement the therapy to improve respectively the inhalation and exhalation phases.
Intrapulmonary Percussive Ventilation (IPV)
This technique of ventilation replaces favorably the conventional Intrapulmonary Positive Pressure Breathing (IPPB) to complement the conventional techniques of rehabilitation. IPV follows the physiological movements of breathing. The patient breathes through a mouthpiece or a mask, which delivers high-flow mini-bursts of air into the lungs. During the percussions, a continued positive airway pressure (CPAP) can, if necessary, be maintained, while a high velocity inflow opens airways and enhances intra-bronchial secretion mobilization. The system is opened and consequently, there is no risk of trauma by excess pressure. This method is not tiresome and can be used during long sessions of 15 minutes with patients. To be fully efficient, the treatment must be given daily and continuously adapted to the clinical state of the patient. The frequency of treatment should be reduced to 2 or 3 times per week where stabilization of the results occurs.
Obstructive, restrictive or combined syndromes are treated in different ways. Obstructive syndrome occurs progressively when the person with MS suffers from swallowing disorders, bronchitis or broncho- pneumonia. In association with antibiotic and regular drainage, the use of high frequency percussions at low flow rate limits congestion and cleans the deepest airways. After stabilization of results, the restrictive aspects are treated in the manner which is described below.
The IPV uses low frequency percussions with high airflow and progressive growing of the inspiratory phase of the percussions. This method allows a slow and progressive recovery of the pulmonary compliance. It acts by reduction of the micro atelectasies, stretching of the intercostal muscles, mobilization of the diaphragm, mobilization of the costo-sternal and costo-transverse joints and ventilation of the pulmonary fields with high resistance (cyphosis, scoliosis).
In case of very low vital capacity, oxygen desaturation, sometimes tachycardia during the speech production, IPV with very high frequency at low flow rate improves quickly the diffusion of gases and the quality of life of the patient.
Controlled or assisted ventilation
Patients who complain of dyspnea, shortness of breath, choking, diurnal or nocturnal oxygen desaturation, may be treated with nasal BIPAP (Bi-level Positive Airway Pressure). In case of severe respiratory insufficiency, an assisted ventilation can improve the quality of life of the patient and avoid tracheostomy.
Air stacking
This technique is difficult and requires much attention and concentration. It consists of successive inhalations of air and setting up of a greater volume in the lungs for a further emission. This method may be helpful for patients who are not easy tired and who have a very low volume. For other patients, the same method may be used by way of an assisted or controlled ventilation.