ALS is a fatal neurodegenerative disease primarily affecting upper and lower motor neurons. In this case, the patient was suspected of having limb-onset ALS, presenting with symptoms in the upper and lower limbs. In addition, there was mild cognitive impairment. Currently, there is no agreement on the anesthetic method of ALS patients undergoing hemorrhoidectomy and hemorrhoidal artery ligation. The concerns about the patient were mainly minimizing the influences to the function of motor and cognition, meeting the analgesic requirement and preventing the perioperative risk of respiratory, bulbar, and autonomic nervous system complications. Hence, real-time ultrasound-guided sacral plexus block combined with mild sedation would be the best option for the patient after the discussion of the multidisciplinary team.
Generally, general anesthesia, neuraxial blockade and peripheral nerve block can meet the surgical requirements of patients with hemorrhoids. However, for ALS patients, the anesthetic goal is to satisfy the analgesic requirement with the least variety of drugs, the smallest amount of drugs, and the simplest techniques without affecting neurological function. The research showed that general anesthesia can be used in ALS patients, but it has a risk because many general anesthetics have different degrees of respiratory depression, and mechanical ventilation is often needed [8]. Muscle relaxants such as depolarizing neuromuscular blockers are strongly avioded, and nondepolarizing neuromuscular blockers should be used with caution [9, 10]. Spinal and epidural anesthesia are conflicting according to previous studies. Although it is safely used in ALS patients, patients with neurological diseases experience worsening neurologic symptoms and neurological sequelae after spinal anesthesia [11–13]. In terms of avoiding respiratory failure, protecting laryngeal reflexes, and maintaining hemodynamic stability, peripheral nerve blocks have advantages over other anesthesia methods[7].
The sacral plexus is considered to be formed anatomically by the lumbosacral trunk and the ventral rami of the first three sacral spinal nerves and descending portion of the fourth sacral spinal nerve, which innervates the skin and muscles of the gluteal region, posterior compartment of the thigh, popliteal fossa, posterior and lateral compartments of the leg, and dorsum of the foot [14]. Ultrasound-guided regional nerve block greatly increases the accuracy of local anesthetic administration around the nerve, and the advantages of ultrasound guidance include visualization of anatomic structures, reduction of local anesthetic requirements, improvement in anesthetic block quality and prevention of fatalities [15]. In addition, real-time ultrasound guidance can provide anatomical positioning images of the nerve and the dynamic trajectory of the puncture needle. Dexmedetomidine is a highly selective α2-adrenergic receptor agonist with sedative, analgesic, anti-anxiety and hibitory effects on sympathetic nervous activity with minimal respiratory depression [16]. Clinical trials have demonstrated that dexmedetomidine has a protective effect on the cognitive function of patients with mild cognitive impairment [17, 18]. Therefore, real-time ultrasound-guided sacral plexus block combined with dexmedetomidine sedation seems to be an effective and safe technique for ALS patients with hemorrhoids.
In summary, this case presents the use of real-time ultrasound-guided sacral plexus block combined with mild sedation in a patient with a 2-year history of ALS and subsequent hemorrhoidectomy and hemorrhoidal artery ligation. The anesthetic strategy successfully met the demands of the surgery and avoided respiratory and neurological complications. However, the efficacy of our strategies may be affected by selection bias because of the nature of case reports. Further studies are needed for this high-risk patient population.