Anesthesia and Huntington’s Disease
For many years, the question of how to best use anesthesia in people with Huntington’s Disease (HD) has puzzled medical professionals. With an occurance of about 5 cases per 100,000 people in the US and Europe, HD is considered to be rare, and anesthesiologists are not likely to come across patients with HD very often. While the medical and scientific communities are yet to develop standards for anesthetic management in people with HD, research has uncovered certain aspects of HD that must be carefully considered when anesthesia is introduced.
Like any other patient, someone with HD would require anesthesia for many surgical situations. However, HD can cause anesthesia to also be necessary for situations that wouldn’t usually require anesthesia for a non-HD person. An example of this is dental care: for someone with later stage HD, chorea and behavioral changes associated with HD would make it difficult to have a dental filling done without anesthesia.
The most prominent interaction between the physiology of HD and common anesthetic agents happens as a result of the bulbar dysfunction seen in many HD cases. The bulbar region of the brain includes the cerebellum, medulla, and pons, and is responsible for controlling many involuntary functions that keep us alive. Many individuals with HD experience bulbar dysfunction, which typically manifests in the form of chorea, or uncontrollable movements that can affect all muscles, including respiratory muscles. Involuntary movements in the respiratory muscles can increase patients’ risk for pulmonary aspiration, or inhalation of the stomach contents. While pulmonary aspiration can happen to anyone under anesthesia, chorea in HD patients increases this risk, so it is important for an anesthesiologist to consider this when they are anesthetizing someone with HD.
Because of this increased risk, a rapid and safe recovery has been identified as a common goal for using anesthesia in patients with HD. The longer they remain unconscious from the anesthesia, the greater their risk of experiencing pulmonary respiration. Thus, fast-acting agents are generally seen to work well for individuals with HD. An example of a fast-acting and effective anesthetic is sevoflurane, which is used to induce and maintain the effects of general anesthesia. Sevoflurane is often used in combination with desflurane, a substance used to maintain the effects of anesthesia in a patient. It is administered via inhalation in a mixture of nitrous oxide and oxygen, and is effective in HD patients because its effects wear off rapidly after administration is discontinued as compared to other anesthetic agents. This allows for rapid recovery and minimizes HD patients’ risk of pulmonary aspiration. Conversely, anesthetic agents such as sodium thiopental and succinylcholine are reported to cause prolonged apnea in individuals with HD, making them unideal for anesthetizing this population due to the increased risk of pulmonary aspiration after prolonged unconsciousness.
In addition to the complications of bulbar dysfunction, there are also other considerations that anesthesiologists must note when using various anesthetic agents in individuals with HD. Among these considerations are the interactions between drugs commonly prescribed to treat the symptoms of HD with the anesthesia. Tetrabenazine is the only drug currently FDA approved specifically for treating the symptoms of HD — as opposed to drugs that are prescribed to individuals with HD but originally designed to treat something else. Since tetrabenazine primarily treats chorea symptoms in HD patients, it has the potential to interact with the bulbar function and increase the risk of pulmonary aspiration for someone with HD under anesthesia. The official recommendation for those taking tetrabenazine is to consult an anesthesiologist, as the drug could influence how the anesthesia affects the central nervous system. Additionally, many antipsychotic drugs which are commonly prescribed to people with HD, including haloperidol and chlorpromazine, commonly include the side effect of suppressing movements. While this often helps treat chorea as well as psychosis in HD patients, it also has the potential for adverse interactions with various anesthetic agents in ways that have not yet been widely researched.
Other factors to consider while evaluating an individual with HD for anesthetic care include age, nutrition, and their ability to qualify for certain types of anesthesias. Increased frailty is commonly seen in older individuals with HD, and their symptoms often prevent them from being able to fully cooperate with an anesthesiologist, making this an important consideration for anesthesiologists. Malnutrition can be seen in HD patients as they progress into the later stages of the disease, as it can be difficult to eat and/or retain their food. Various levels of under or malnutrition alter the physiology of the body in ways such as: shifting electrolyte and fluid levels, causing metabolic abnormalities, and increasing risk for hypothermia — all of which change the ways in which the body responds to drugs, including anesthesia. Finally, chorea can make it difficult to consider anesthetic options such as spinal anesthesia, as the uncontrollable chorea movements make it difficult to get proper injection placement, which is crucial for patient safety as well as the ability of the anesthesia to work effectively.
Various factors that dictate the proper treatment of those with Huntington’s Disease when using anesthesia have come to light in recent years. Despite this, a consensus on the best practices for anesthetic management of individuals with HD is still yet to be determined. Until further research is conducted, the existing literature suggests a few main factors that anesthesiologists must carefully consider while using anesthesia in patients with HD. The first is the response time of the anesthetic agent to minimize the risk of pulmonary respiration. Next, they must consider the interaction of the anesthesia with other drugs the patient may be taking. Finally, the physical condition of the patient must be taken into consideration, including nutrition level and which options are feasible for each patient. While a firm consensus on the anesthetic management of people with HD may never be reached due to the high variability of considerations between cases, more research on the interactions of HD and anesthesia is necessary to determine how to best treat these individuals.
Further Reading
Cangemi Jr, C. F., & Miller, R. J. (1998). Huntington’s disease: review and anesthetic case management. Anesthesia progress, 45(4), 150. Click here to read about the challenges of using anesthesia with HD, and one case study using sodium thiopental and succinylcholine.
Esen, A., Karaaslan, P., Akgün, R. C., & Arslan, G. (2006). Successful Spinal Anesthesia in a patient with Huntington’s Chorea. Anesthesia & analgesia, 103(2), 512-513. Click here to read about the challenges presented by using spinal anesthesia in HD patients and how this was successfully done in one case study.
Kang, J. M., Chung, J. Y., Han, J. H., Kim, Y. S., Lee, B. J., & Yi, J. W. (2013). Anesthetic management of a patient with Huntington’s chorea-A case report. Korean journal of anesthesiology, 64(3), 262. Click here to read a case report using anesthesia in an emergency operation on an HD patient.
MacPherson, P., Harper, I., & MacDonald, I. (2004). Propofol and remifentanil total intravenous anesthesia for a patient with Huntington disease. Journal of clinical anesthesia, 16(7), 537-538. Click here to read about one case study using propofol anesthesia in a HD patient in a dental case.
McConachie, I. (Ed.). (2009). Anesthesia for the high-risk patient. Cambridge University Press. This book includes concerns with using anesthesia in the malnourished, which can be a problem for HD patients.
Nguyen, P. T., Meeks, D., & Liotiri, D. (2017). Anaesthesia and orphan disease: airway and anaesthetic management in Huntington’s disease. BMJ case reports, 2017, bcr-2017. Click here to read about airway management when using anesthesia in HD patients.
Yadava, A., Battacharya, P. K., Jain, R. K., & Agarwa, R. C. (2006). Anaesthesia and huntington’s chorea. Indian J. Anaeth, 50(1), 47-48. Click here to read this article, which describes one particular case of anesthesia in HD, and discusses the risks associated with anesthesia and HD.