Solunum 2002 Cilt: 4 Say›: Ek 2 Sayfa: 321-322

NEUROMUSCULAR DISEASES LEADING TO RESPIRATORY INSUFFICIENCY

Piraye SERDARO⁄LU

‹stanbul Üniversitesi ‹stanbul T›p Fakültesi, Nöroloji Anabilim Dal›, ‹STANBUL.

Neuromuscular disorders can lead to respiratory phrenic nerve, “Churg-Strauss disease” in which insufficiency mainly due to the affection of respiratory asthmatic respiratory disease is evident. muscles, namely upper airway muscles, respiratory One of the most important disease groups which alter accessory muscles, diaphragm and even abdominal respiration are the diseases of neuromuscular junction, muscles. However, mechanisms other than respiratory “Myasthenia gravis (MG)” being the most important muscle involvement, such as alteration of mechanical and most frequent. Myasthenia gravis is the autoimmune properties of respiratory apparatus (i.e. scoliosis), disease of nicotinic acetyl choline receptors (AchR) appearance of muscle fatigue, alterations in the control at the post synaptic membrane of nerve-muscle junction. of ventilation, dysfunction of the upper airway, Patients usually present with asymmetrical ptosis and/or involvement of heart muscle may also contribute to diplopia, bulbar symptoms such as chewing, speech respiratory problems during the course of the and swallowing difficulties, and generalized fatigue. neuromuscular disorders. Complaints fluctuate during the day. If the respiratory Neuromuscular structures which promote problems in muscles are involved, myasthenic crisis is apparent. respiration when involved are related motor neurons, This is an emergency problem and one cannot see the peripheral nerves-mainly phrenic nerve-, related nerve- fluctuation during the day in this fulminating clinical muscle junctions and respiratory muscles themselves. picture. The disease can worsen by infections, In this report, neuromuscular diseases of these structures pregnancy, puerperal period, and by some medicines. will be presented. Resting restores the lost functions by the recovery of Among motor neuron diseases, “poliomyelitis” has muscle strength. Although main treatment regimen has been eradicated after the employment of its specific to comprise immune suppressive medication, vaccination. “Amyotrophic lateral sclerosis (ALS)” is symptomatic period necessitates symptomatic anti- a degenerative disease of all motor neurons, which cholinesterase therapy. The dose of anti-cholinesterase progress in few years to death due to respiratory medication has to be adjusted due to symptom intensity insufficiency. When bulbar involvement occurs, it and on patient basis. Although it is life saving in most usually presents with swallowing difficulties, which occasions, excessive anti-cholinesterases themselves may cause aspiration. Respiratory involvement appears cause muscle weakness and they also augment bronchial later in the course, which urges ventilatory support. secretion. Respiratory problems in MG occur due to One of the emergency medicine topics is “acute several reasons: When swallowing difficulties are inflammatory demyelinating neuropathy (AIDP), i.e. evident, aspiration and its consequences are the main Guillain Barre syndrome (GBS)”. This neuropathy problem. Anti-cholinesterase treatment can be another causes muscle weakness as well as sensory impairment problem with augmented production of bronchial due to drop out of peripheral nerves, which is caused secretion. This is especially an enigma when there is by an immunological attack. Progression limits itself critical respiratory muscle involvement. The scenario in 4 weeks. If progression reaches to respiratory then, is the increased bronchial secretion, effort to muscles, which is a frequent state after cranial nerve cough with already weak muscles and further fatigue involvement, intensive care conditions are needed. during the process and become increasingly unable to Disease has a plateau for several weeks, after which expectorate after each effort. A vicious circle is evident it regresses. Therefore, ventilatory support and and is usually amplified by the superimposed infections. prevention from infections at this time is life saving. Respiratory insufficiency at any point of this vicious Other neuropathies, which cause respiratory problems circle has to be expected and patient has to be secured much less frequently, are the phrenic nerve involvement in terms of respiration as soon as possible. Another during “chronic inflammatory demyelinating neuromuscular junction disease “Lambert- Eaton neuropathy (CIDP)”, a form of hereditary neuropathy myasthenic syndrome (LEMS)” can also lead to “Charcot Marie Tooth disease (CMT)” which affects respiratory problems due to muscle fatigue as well as 321 P SERDARO⁄LU

small cell carcinoma of lung, which is a frequently Pompe disease” for example, can present with respiratory associated condition. The toxic neuromuscular disease, insufficiency, even before the weakness in extremities. “botulismus” is another condition, which usually urges Some “congenital myopathies” such as multicore disease, intensive ventilatory support. desmin myopathies, rod myopathy, or some “metabolic Myopathies, in which the main damage is in muscle myopathies” such as debrancher enzyme defect, some fiber itself, are the main neuromuscular causes of mitochondrial myopathies are other examples. In respiratory insufficiency. In inflammatory myopathies, “myotonic dystrophy (DM)” patients usually experience direct involvement of respiratory muscles is rare. chronic hypo-ventilation. However, interstitial lung disease, which may One specific myopathy of interest is “critical care myopathy accompany, especially Jo-1 myositis can cause mild or myosin loss myopathy”. This myopathy developes in respiratory problem. The end stage of other hereditary patients who had been intubated and stayed in the intensive myopathies of dystrophic, structural or metabolic origin care unit. It is usually comes into attention when the is usually respiratory insufficiency. The diminishing patient cannot be weaned from the respirator. Patient is respiratory function can be the result of frequent also quadriplegic. Sepsis, high dose corticosteroids, non- development of scoliosis or other chest deformities. depolarizing blocking agents are thought to be the Cardiomyopathy, which might accompany the existing underlying causes, solely or in combination. If these myopathy can be another cause of breathing problems. conditions are reversed, the disease is self limited. At the end stage of any muscle disease, the weakness Respiratory muscle training, starting from the onset of of respiratory muscles limits coughing and causes the disease is important. However, the physician has frequent lung infections which in turn can urge assisted to be careful about the fatigue generating conditions ventilation. However, some myopathies frequently and such as myasthenia gravis or metabolic diseases, in selectively involve respiratory muscles. “Adult onset which normal training pattern may be harmful.

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