Diaphragmatic paralysis pathophysiology
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Mahda Alihashemi M.D. [2]
Overview
It is thought that diaphragmatic paralysis is the result of paralysis of cervical nerve roots( C3-C5 ). Diaphragmatic paralyses can be unilateral or bilateral according to involvemnet of one or two leaflets of diaphragm. In the case of unilateral diaphragm paralysis, it is compensated by other hemidiaphragm or accessory muscles of respiration. In bilateral diaphragmatic paralysis, accessory muscles do all of the work of breathing and finally it may lead to ventilatory failure. Early diaphragmatic paralysis may be one of the manifestations of genetic neuromuscular disorders such as spinal muscular atrophy (Werdnig-Hoffmann disease) and acid maltase deficiency. On gross and microscopic pathology, there are no characteristic findings of diaphragmatic paralysis.
Pathophysiology
The main muscles of inspiration include:
- Diaphragm (most important)
The muscles of expiration:
- Internal intercostals
- Muscles of the abdominal wall
- Rectus abdominus
- Internal and external obliques
- Transversus abdominus
Pathogenesis
- The diaphragm is the musculo-fibrous membrane. It has two parts: non-contractile central fibrous and peripheral muscular components. [1][2][3]
- Peripheral muscular section has two fibers:
- Type 1: slow and fatigue resistant fibers: play roles in low intensity, continual cycle of breathing
- Type 2: fast fibers: play roles in rapid and intense situations such as:
- Talking
- Singing,
- Sneezing,
- Defecation
- Acute hyperventilation
The diaphragm create negative intrathoracic pressure and facilitates movement of air into the lungs. It is innervated by cervical nerve roots ( C3-C5 ) via the phrenic nerves.[4][5]
Diaphragmatic paralysis can be unilateral or bilateral according to involvemnet of one or two leaflets of diaphragm.
Diaphragmatic paralysis is an uncommon cause of dyspnea.
It is understood that diaphragmatic paralysis is the result of paralysis of cervical nerve roots (C3-C5 ).
In the case of unilateral diaphragm paralysis, it is compensated by other hemidiaphragm or accessory muscles of respiration.
In bilateral diaphragmatic paralysis, accessory muscles do all of the work of breathing and finally it may lead to ventilatory failure.
Bilateral diaphragmatic paralysis is usually seen with generalized muscle weakness. In some cases, the diaphragm is the only muscle involved.
Genetics
Early diaphragmatic paralysis may be one of the manifestations of genetic neuromuscular disorders such as spinal muscular atrophy (Werdnig-Hoffmann disease) and acid maltase deficiency.[6]
Gross Pathology
- On gross pathology, there are no characteristic findings of diaphragmatic paralysis.
Microscopic Pathology
- On microscopic histopathological analysis, there are no characteristic findings of diaphragmatic paralysis.
References
- ↑ Mizuno M (1991). "Human respiratory muscles: fibre morphology and capillary supply". Eur. Respir. J. 4 (5): 587–601. PMID 1936230.
- ↑ Sánchez J, Medrano G, Debesse B, Riquet M, Derenne JP (1985). "Muscle fibre types in costal and crural diaphragm in normal men and in patients with moderate chronic respiratory disease". Bull Eur Physiopathol Respir. 21 (4): 351–6. PMID 4041660.
- ↑ Roussos C, Macklem PT (1982). "The respiratory muscles". N. Engl. J. Med. 307 (13): 786–97. doi:10.1056/NEJM198209233071304. PMID 7050712.
- ↑ Lieberman DA, Faulkner JA, Craig AB, Maxwell LC (1973). "Performance and histochemical composition of guinea pig and human diaphragm". J Appl Physiol. 34 (2): 233–7. doi:10.1152/jappl.1973.34.2.233. PMID 4265565.
- ↑ Fell SC (1998). "Surgical anatomy of the diaphragm and the phrenic nerve". Chest Surg. Clin. N. Am. 8 (2): 281–94. PMID 9619305.
- ↑ Sivan Y, Galvis A (1990). "Early diaphragmatic paralysis. In infants with genetic disorders". Clin Pediatr (Phila). 29 (3): 169–71. doi:10.1177/000992289002900305. PMID 2407409.