**5. Intraoperative nondepolarizing neuromuscular blockers in ALS patients**

While depolarizing neuromuscular blockers are contraindicated, nondepolarizing neuromuscular blockers such as rocuronium has been successfully used along with propofol and remifentanil. In a case of a 47 year-old ALS patient with a humerus fracture, general anesthesia was induced by propofol, rocuronium and remifentanil [32]. At the end of an uneventful operation, TOF (train-of-four) was great than 0.90 but muscle strengthen and tidal volume were not sufficient [32]. Rocuronium and other nondepolarizing neuromuscular blockers are competitive antagonists of the post-synaptic acetylcholine receptor, leading to prolonged weakness or flaccid paralysis. In the above case, 2 mg/kg sugammadex was given intravenously to quench the residual remifentanil in the patient [32]. Suggammadex rapidly forms a complex with free rocuronium, which is quickly filtered by the kidney. Thus, the duo of rocuronium and sugammadex has been frequently and safely used in general anesthesia of ALS patients.

#### **6. Postoperative care for ALS patients**

Tracheal extubation should be done after the patient is fully awake. This will maximize the laryngeal reflex function. Regardless, the respiratory status of the patient needs be closely monitored. In some cases, postoperative ventilation is needed, and weaning ventilation should be prolonged. Patients who had noninvasive positive-pressure ventilation (NPPV) preoperatively require NPPV being placed once again postoperatively [33]. There is a need for effective pain relief but the

use of agents that depress respiration should be avoided. It is recommended to use peripheral nerve blockers and local or regional approaches to manage postoperative pain. Postoperative oxygen use is not recommended due to the instability of respiratory control in ALS patients. When opioids are used, the dosages should be tightly controlled in conjunction with monitoring methods such as pulse oximetry to reduce morbidity and mortality.

In case of an ALS patient with rectal cancer, laparoscopic low anterior resection with diverting loop ileostomy and total abdominal hysterectomy were performed under general anesthesia using the combination of propofol and rocuronium for induction and the regime of sevoflurane and remifentanil for maintenance [34]. After the surgery, glycopyrrolate and pyridostigmine bromide were used to reverse the muscle relaxant effects of rocuronium [34]. Postoperative use of fentanyl controlling analgesia in the patient consisted of intermittent low doses within 48 hours, and the patient recovered uneventfully [34]. The use of fentanyl should be cautioned against as it causes respiratory muscle rigidity and subsequent respiratory dysfunction in ALS patients. Postoperative pain should be carefully managed based on the unique circumstances of ALS patients.

### **7. Anesthesia during labor and delivery in ALS patients**

Because ALS onset is usually late in life, there are few cases associated with labor and delivery in ALS patients. How pregnancy affects the progression of ALS is still unclear. It has been reported that ALS patients have successfully carried pregnancies to term [35]. The timing and the methods of delivery are chosen based on the disease stage. The perineum and the uterine musculature are not affected by ALS, and thus vaginal delivery is a preferred method for labor. Progressive shortness of breath or respiratory distress during pregnancy are indicators for emergency Caesarean section [35]. ALS patients are often unable to increase respiration to match oxygen need in labor. As respiratory burden worsens at the end of pregnancy, anesthetic management during Caesarean section becomes increasingly challenging.

There is no formal recommendation for anesthesia management of Caesarean section in women with ALS. It has been reported that epidural anesthesia has been used successfully with no evidence of anesthesia complications in ALS patients. In a case of 38-week pregnant woman with 10-year history of ALS, sequential combined spinal-epidural anesthesia was successful for Caesarean section [36]. Before delivery, neurological assessment on the patient showed progressive muscle weakness, severe dysarthria and dysphagia. The patient presented with quadriparesis, hypotonia, and hyperreflexia, and severe restriction on spirometry with a high risk of respiratory failure. Prior to anesthesia, doses of ranitidine, metoclopramide and dexamethasone are given. Hyperbaric bupivacaine 6 mg plus fentanyl 10 μg were given through the spinal needle and 5 minute later with 0.25% isobaric bupivacaine in 10 ml through the epidural catheter to block T5. The surgical procedure was uneventful. Thus, while vaginal delivery is ideal, delicate regional anesthesia can achieve good outcomes for Caesarean section.

#### **8. SMA overview**

SMA is a spectrum of MNDs occurring predominantly in infants and children. The primary causal factors for this inherited disease are deletions or mutations

*Motor Neuron Disease and Delicate Anesthesia Choices – Anesthesia for Motor Neuron Disease… DOI: http://dx.doi.org/10.5772/intechopen.113276*

of the *Smn1* gene. Generally, *Smn1* gene deficiency causes the degeneration and eventual death of spinal anterior horn neurons with decreased brainstem nuclei. SMA type I (Werdnig-Hoffmann) shows symptoms before 6 months of age and progresses rapidly in the first year of life. SMA types II and III (Kugelberg-Welander) manifest at 6–18 months of age and later in childhood, respectively. SMA type 0, the most severe and earliest onset form, is fatal without respiratory support. The symptoms of SMA type IV first appear in adulthood, presenting with minimal disability.

Infants and children with SMA often need anesthesia because of diagnostic procedures and surgical treatments. Common procedures associated with SMA type I patients are gastrostomy, fundoplication, tracheotomy, and muscle biopsy. Common procedures for SMA type II and III patients include correction of scoliosis and club foot, joint contracture release, and muscle biopsy. SMA type III patients can reach reproductive age and thus cesarean sections may be performed on these patients.

#### **9. Anesthetic management of SMA patients**

SMA patients have prominent spinal and other bone deformities that require surgical correction to improve patients' quality of life and extend their survival time. In a case of a 14-year-old SMA type II male patient with a previous operation for scoliosis, the patient was scheduled for an implant removal because of infection [37]. General anesthesia was used and 2 mg dormicum, 20 mg lidocaine, 80 mg propofol, 25 μg fentanyl were used for the induction of anesthesia [37]. No neuromuscular blockers were used [37]. The patient was intubated with a spiral cuffed number 5 tube with direct laryngoscopy when his Bispectral Index Score, which monitors consciousness, was 46 [37]. Foe anesthesia maintenance, one percent sevoflurane and remifentanyl infusion of 0.1–0.2 mg/kg/min were used [37]. The surgery was uneventful and an intravenous administration of 25 mg dexketoprofen was given for postoperative analgesia [37]. The patient was successfully extubated and followed up in intensive care for one day postoperatively [37]. As in this case study, general anesthesia for major surgery in SMA patients should be performed using minimal opioids, whereas muscle blockers are to be used judiciously. Combining sevoflurane with remifentanil, which quickly reverses the muscle relaxant effect of sevoflurane, can achieve optimal anesthesia management and postoperative recovery.

Likewise, there are two cases of general anesthesia for surgical correction of heart defects in SMA type II patients [38]. A 23-day-old SMA type 2 patient successfully underwent pulmonary banding and patent ductus arteriosus ligation with 4 mg thiopental, 4 mg fentanyl, and 1.5 mg rocuronium being used for anesthesia induction and maintenance [38]. Atrial and ventricular septal defect closure and pulmonary artery reconstruction were performed on a 17-month-old patient using rocuronium, pentothal, dormicum, and fentanyl, with maintenance via 0.1 mg/kg/h precedex and 0.6–0.7 minimum alveolar concentration (MAC) of sevoflurane [38]. Both patients were extubated and recovered uneventfully [38].

In a case of an 8 year-old SMA type II patient, a dislocated hip was corrected with a combination general and local anesthesia regimen [39]. Similar to the aforementioned cases, the patient was induced by sevoflurane followed by intravenous administration of fentanyl and propofol [39]. Spinal anesthesia was achieved with 2 ml 0.5% hyperbaric bupivacaine with an epidural catheter in the L3–L4 space [39]. The patient successfully recovered.

Graham *et al*. summarizes anesthesia induction and management for 56 cases of SMA types I, II and III [40]. Midazolam via both enteral and intravenous routes or a combination of ketamine and midazolam were used for premedication [40]. The most common method for airway support is standard endotracheal intubation. Propofolbased intravenous anesthesia is the most common approach during the procedure. Cisatracurium is the first line neuromuscular blocker, while fentanyl and remifentanil are the two most commonly used intraoperative opioids.

#### **10. SMA patient perioperative care essentials**

In a retrospective chart study, thoracolumbar spinal deformity corrections were performed in 34 SMA type I and II patients in a single medical center from 1990 to 2015 [41]. The study reported that in the 34 patients, there were two occurrences of pneumonia (6%), no postoperative re-intubation or unplanned tracheostomies, and no deaths [41]. Because SMA is associated with impaired gastrointestinal function and malnutrition, most SMA patients need perioperative total parenteral nutrition (TPN), whichbypasses the gastrointestinal tract and delivers nutrients to the venous system. Additionally, these patients must be on continuous NPPV for adequate respiratory support.

Pulmonary disease and bulbar dysfunction are strongly associated with SMA and pose anesthetic risks. Preoperatively, pulmonary consultation should be done in all SMA patients. Pulmonary function tests should be conducted. Most SMA patients have difficulties with intubation and thorough evaluations on indicators for intubation should be considered. Preoperative training on NIPPV should be conducted if the patient currently does not have respiratory support. Preoperative airway evaluation is mandatory and establishes a plan for intubation difficulties due to. SMA patients are susceptible for to hypo- and hyperglycemia. Thus, blood glucose levels should be closely monitored. Cardiac function needs to be evaluated preoperatively because SMA is often associated with cardiac malformations. SMA type I and II patients often have gastroesophageal reflux and should be evaluated accordingly.

Intraoperatively, endotracheal intubation with positive pressure ventilation should be applied as respiratory support. Depolarizing muscle relaxants such as succinylcholine should be constrained and the dose of nondepolarizing muscle relaxants should be tightly controlled. If nondepolarizing muscle relaxants are used, neuromuscular function should be monitored. Inhaled anesthetics should be avoided in favor of the intravenous route. Short acting opioids are used intraoperatively when opioids are needed. TPN infusion should be maintained to avoid hypoglycemia. SMA patients typically have 2 more hours of anesthetic time than healthy patients.

Postoperatively, SMA patients should be monitored in the intensive care unit. Generally, these patients require 5–7 days of intensive care even with minor procedures. Most SMA type I patients need postoperative ventilatory support. Postoperative oxygen supplementation is needed for the first 24 hours. Opioids, acetaminophen, and NSAIDs, or all three in combination should be used as postoperative pain management. Opioids may induce respiratory distress in SMA patients. Benzodiazepines are used to manage muscle spasms and discomfort. However, postoperative pain management can largely be tailored to the individual.

*Motor Neuron Disease and Delicate Anesthesia Choices – Anesthesia for Motor Neuron Disease… DOI: http://dx.doi.org/10.5772/intechopen.113276*

#### **11. Kennedy's disease overview and anesthetic management**

Kennedy's disease (KD), also known as spinal and bulbar muscular atrophy, is a rare adulthood-onset X-linked disease that results in the degeneration and eventual death of lower motor neurons. The major symptoms of KD are tongue atrophy, dysarthria, dysphonia and dysphagia, along with limb and bulbar muscle atrophy, weakness and fasciculations [42]. KD is a CAG trinucleotide expansion repeat disorder in the androgen receptor gene. Anesthetic management can be challenging. Laryngospasm and pulmonary aspiration have been reported as primary anesthetic risks in KD patients. Both nondepolarizing and depolarizing neuromuscular blockers induce hyperkalemia in KD patients [42]. In a 71-year old KD male patient who underwent a tracheotomy, the surgical procedure was performed under local anesthesia by ultrasound-guided superior laryngeal nerve block and superficial cervical plexus block via 2% lidocaine [42]. The procedure was uneventful and the patient reported no discomfort [42]. In a 61-year-old male KD patient who underwent a left thigh sarcoma excision, general anesthesia with endotracheal intubation was induced by 150 mg propofol and 100 μg fentanyl, and maintained with inhalational anesthesia [43]. The patient recovered without any postoperative complications.

#### **12. Isaacs' syndrome overview and anesthetic management**

Isaacs' syndrome, a peripheral MND, manifests with peripheral nerve hyperexcitability. Symptoms include cramps, muscle stiffness, muscle twitching, and pseudomyotonia. The major cause of Isaacs' syndrome is antibodies against the voltage-gated potassium channel complex in the peripheral nerves. Anticonvulsive medications and immunomodulation therapy are used to control the progression of this disease. The onset of Isaacs' syndrome is mainly in early adulthood or onwards.

In a 74-year-old female Isaacs' syndrome patient who underwent a surgery for open rotator cuff repair, total intravenous anesthesia with propofol, remifentanil, and atracurium was used under continuous neuromuscular monitoring [44]. The surgical procedure and postoperative recovery were smooth without any anesthetic complications. Because Isaacs' syndrome is a rare disorder, anesthetic management and outcomes have not been extensively explored in literature.

#### **Conflict of interest statement**

The authors have declared that no conflict of interest exists

### **Declaration of interests**

The author declares no competing interests.

*Motor Neurons – New Insights*
