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Phrenic Nerve Reconstruction for Diaphragmatic Paralysis and Ventilator Dependency 117 Phrenic Nerve Reconstruction for Diaphragmatic Paralysis 10 and Ventilator Dependency Matthew Kaufman, Thomas Bauer, Mary Massery, and John Cece Introduction However, neuromuscular dysfunction within the respiratory system has generally been the sole The integration of advanced surgical methods responsibility of the clinician, other than referral aimed at restoring form and function in the for tracheostomy or, more recently, diaphragm human body into the paradigm of rehabilitation pacemakers. This lack of communication limits medicine has, until recently, lagged in the area of successful reversal of the disorder when noninva- neuromuscular respiratory disorders. For several sive methods fail. It is the fault of neither the cli- decades, reconstructive surgeons have been nician nor surgeon in developing, recognizing, or reporting on various procedures to improve func- promoting similar surgical options for patients tion to a paralyzed arm or leg, including recon- with neuromuscular respiratory disorders. Rather, structive nerve surgery, muscle or tendon it has been a lack of focus or basic training of any transfers, and joint fusions. A natural synergy has surgical specialty to pursue functional restoration occurred over time, where clinicians caring for of the neuromuscular pathways in the respiratory patients with paralysis and spinal cord injury system and a misconception that most central have an understanding of the surgical options and and/or peripheral nerve lesions within this sys- communicate with their surgical colleagues tem cannot be overcome. regarding proper patient selection for operative An anatomical basis for pursuing surgical intervention. techniques to reverse respiratory paralysis exists just as it does for any other peripheral motor sys- tem in the human body. For direct insults to the M. Kaufman, MD, FACS ( *) • J. Cece, BAS primary peripheral respiratory nerve, i.e., the The Plastic Surgery Center, Institute for Advanced phrenic nerve, microsurgical methods of nerve Reconstruction, 535 Sycamore Ave, Shrewsbury, reconstruction can be applied to restore or sup- NJ 07702, USA plement axonal continuity and overcome dia- e-mail: [email protected]; [email protected]; phragmatic paralysis. [email protected] Successful surgical intervention to restore T. Bauer, MD neuromuscular recovery following injury can Jersey Shore University Medical Center, occur provided the following basic principles 1945 NJ 33, Neptune, NJ 07753, USA apply. First, there must be inherent maintenance e-mail: [email protected] of the ability for peripheral nerve regeneration M. Massery, PT, DPT, DSc (*) within the individual’s nervous system. The Massery Physical Therapy, 3820 Timbers Edge Lane, capacity for nerve regeneration is maintained in Glenview, IL 60025, USA e-mail: [email protected] peripheral nerves, even in patients with spinal © Springer International Publishing Switzerland 2017 115 A.I. Elkwood et al. (eds.), Rehabilitative Surgery , DOI 10.1007/978-3-319-41406-5_10 [email protected] 116 M. Kaufman et al. cord injury. Second, surgical methods must be meticulous and precise. Surgical precision pro- vides the scaffold upon which the regenerative process can occur. Finally, there must be ade- quate rehabilitation of the muscle once reinnerva- tion has been confirmed. Restoration of normal or near-normal nerve conduction to a muscle, especially a rather large muscle like the dia- phragm, will only result in muscle recovery and regrowth if intensive rehabilitation is instituted. Insults to the central nervous system, including spinal cord injury, stroke, or tumor, may result in ventilator dependency when the neural pathways Fig. 10.1 Exposure of diaphragm through transthoracic are interrupted between the brainstem respiratory approach and mobilization of pedicled rectus abdominis centers and the peripheral circuitry. Diaphragm muscle flap in a cadaver (Courtesy and with gratitude to pacemakers, a topic discussed in detail in the fol- donors of UCLA Donated Body Program) lowing chapter 11 , may offer a tremendous thera- peutic benefit to reduce or eliminate the need for “replaced” by transferring vascularized, inner- mechanical ventilation and minimize the associ- vated muscle from somewhere else in the body, ated morbidity and mortality associated with and expect it to function in a similar manner to that long-term ventilatory support. Unfortunately, which it is replacing, the same may be true for the there are a subset of patients for whom pacemak- diaphragm. When these capabilities are realized ers will provide little or no benefit. through ongoing clinical evaluation, the surgical A requirement for successful application of a options would be comprehensive in nature in terms diaphragm pacemaker is phrenic nerve integrity. of replacing most major components of the neuro- When individuals have insults to their central muscular pathways within the respiratory system. nervous system in locations that also results in Specifically, the absence of a derived impulse due loss of the anterior horn cells, there is resultant to the CNS (central nervous system) disorder peripheral Wallerian degeneration in the phrenic could be overcome by the transmitted impulse nerves. It has been estimated that 18 % of all spi- from the diaphragm pacemaker, a nerve transfer to nal cord injured patients have generalized periph- restore axonal circuitry to the degenerated phrenic eral axonal neuropathy, with tetraplegics having nerve, and a muscle that has not undergone dener- an even higher incidence [ 1]. These patients are vation atrophy (in a high cervical tetraplegic), such often told to expect a life-long dependency on the as the rectus abdominis, may be transferred to ventilator. Recently, we have been able to demon- replace or enhance what may be an irreversibly strate the restoration of phrenic nerve integrity atrophic diaphragm (Fig. 10.1 ). using reconstructive nerve surgery, permitting successful use of a diaphragm pacemaker, a report that supplements an earlier, primary Neuromuscular Anatomy description of these methods [2, 3]. For these and Physiology of the Respiratory unfortunate patients, there may be an option to System overcome the debilitating and life-shortening impact of chronic ventilator dependency. Central Pathways In our quest to have a range of reconstructive surgical options to remedy the neuromuscular dys- The anatomy and physiology of the respiratory function regardless of severity, we are developing system is somewhat unique. There is a baseline methods for diaphragm muscle replacement. Just level of involuntary activity necessary to sustain as facial or upper extremity muscles can be breathing during sleep as well as a conscious [email protected] 10 Phrenic Nerve Reconstruction for Diaphragmatic Paralysis and Ventilator Dependency 117 “override” that may be invoked. Brainstem through a rerouting of impulses from the contra- nuclei transmit impulses through the anterior lateral, uninjured side [ 4–6]. horn cells to initiate an inspiratory effort. Alternatively, respiratory centers in the cerebral cortex may stimulate a respiratory event through The Muscles of Respiration a conscious effort. There are established connec- tions between both sides of the brainstem, After descending to the upper cervical region including a described “cross phrenic phenome- (C3-5), the conduction proceeds extradural through non,” whereby a cord hemisection disrupting the cervical roots and phrenic nerves, downward ipsilateral respiratory activity will be restored toward each hemidiaphragm (Fig. 10.2 ). The ANTERIOR PRIMARY VAGUS DIVISION OF FOURTH CERVICAL PHRENIC PHRENIC INFERIOR CERVICAL BRACHIAL GANGLION PLEXUS INFERIOR LARYNGEAL NERVE TO SUBCLAVIUS INFERIOR MUSCLE LARYNGEAL COMMUNICATING BRANCH FROM BRACHIAL PLEXUS THORACIC CARDIAC VAGUS BRANCH OF VAGUS INFERIOR LARYNGEAL ROOT OF ANTERIOR LUNG PULMONARY PERICARDIAL ANTERIOR BRANCH PULMONARY PLEXUS PERICARDIUM DIAPHRAGM PHRENICO- ABDOMINAL BRANCH RAMIFICATIONS OF PHRENIC Fig. 10.2 Neuromuscular pathway of the respiratory sys- chest cavities; and the intramuscular branching pattern of tem, including the phrenic nerves arising from the third the phrenic nerve within the diaphragm to innervate all through fifth cervical roots; the descent of the phrenic muscular segments nerves through the cervical region, mediastinum, and [email protected] 118 M. Kaufman et al. diaphragm is the primary inspiratory muscle, work- humans also have a smaller branch, called the ing in conjunction with several accessory respira- accessory phrenic nerve, which runs a parallel tory muscles to expand the thoracic cavity in a but often variable course in the neck, typically vertical dimension, while intercostal muscles are joining the more dominant phrenic nerve proper primarily responsible for horizontal expansion of at the base of the neck or in the mediastinum [7]. the ribcage. The entire process is a coordinated After entering the mediastinum, the phrenic ensemble of contraction in the trunk musculature, nerve increases in caliber and travels between the including the trapezius, sternocleidomastoid, pec- lung and midline structures. In the region of the toralis major/minor, small strap muscles of the heart, the phrenic nerves on both sides are located neck (hyoid musculature), intercostals, and abdom- close to or within the pericardial fat and descend inal muscles. The lung expands passively as a result within these tissues to reach their terminal inser- of the facilitated increased
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