June 1, 2012
by Kevin J. McCann, BSc, DDS, FRCD(C)
For every body system there are readily observable characteristics that can be used to assess the structure and function of that system, and to distinguish the healthy from pathologic state. As an example, the cardiovascular system can be assessed through listening to heart and lung sounds, obtaining a blood pressure, and taking a pulse to determine the rate and rhythm of the heartbeat. Essential to distinguishing normal from abnormal is the history that the patient provides the clinician. Again, for the cardiovascular system, questions on exercise tolerance, episodes of dyspnea, energy levels and edema, to provide a few will often provide a good estimate of cardiovascular health. In the event that questions remain, or the disease process needs to be further categorized, there are a number of tests available to assist in the diagnostic process. Mental health status however is somewhat more enigmatic than all of the other body systems. We cannot simply place a stethoscope over the brain to get an idea of how the brain is working, and there are not often overt signs of impending mental health failure. The importance of assessment of mental health status is equally important to the delivery of health care including dental care. Indeed, if certain mental health issues are present, the patient may lack the ability to provide consent for the procedure, or medications being used to manage the mental health problem may interact with those used during dental treatment. The purpose of this article is to provide a brief overview of mental health assessment, and a review of the medications that are often used to manage disorders of mental health.
Obtaining a full history is by far the single most important task in psychiatric assessment.1 History taking in the face of psychiatric illness is complicated not only by the disorder itself, but the stigma that is often associated with the problem. It is easier to talk to a patient about the symptoms of their congestive heart failure, but more difficult to obtain full disclosure about a patient’s suicidal thoughts. The fourth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV),2 published by the American Psychiatric Association provides the language and criteria for classifying mental disorders. The DSM-IV is a complex manual, which is probably best left to mental health professionals to apply correctly. However, psychiatric disorders need not unduly complicate perioperative care, and a thorough understanding of the manual is not required in the non-psychiatric setting. Briefly, the DSM-IV consists of five axes (axis I through axis V), or categories that are used to describe mental disorders. Axis I lists the various clinical syndromes that we would typically think of as the ‘diagnosis’ such as depression, anxiety disorders and so on. Axis II includes developmental disorders that are typically evident in childhood, and personality disorders that affect the individual’s way of interacting with the world. Axis III lists the physical conditions that play a role in the development, continuance or exacerbation of Axis I and II disorders. Axis IV includes the varying psychosocial stressors that can affect the axis I and II disorders, and include events such as death of a spouse and employment changes. The final axis rates the patient’s level of functioning at the present time and the highest level within the past year. Axis V helps to define how axis I through IV are affecting the person and what type of changes could be expected. In order to assess all five of the axes, it is necessary to cover more topics than are often addressed in other physical systems, and will include family and childhood history, educational history, occupational history, medical history, sexual and reproductive history, social history and daily routines, substance abuse history and pre-morbid personality.1 Given the volume of information that needs to be assessed, it is easy to realize that obtaining a thorough and complete psychiatric history requires skill and tact. Poole and Higgo suggest using the initial history as a pro forma and add or modify to it as the interview process continues.1
If the patient’s cognitive status permits him or her to be a reasonable historian, a simple approach to gathering mental health information is to ask the patient if they have ever been under the care of a psychiatrist.3 Knowing the severity of the illness is often better than knowing a specific diagnosis. Patients that have been treated in an in-patient facility generally have more severe illness than those patients treated on an out-patient basis. Asking the patient if they feel that interventions have been beneficial in managing the problem will often provide some insight into the effects of treatment. If medications are part of management, it is crucial to know not only what medications have been prescribed, but to also have an idea of patient compliance and response to medications. Patients who present with a history of substance abuse represent a history taking challenge. Alcohol and recreational drug use is also a topic with stigma issues by both adults and adolescents. Less threatening phrasing of questions about substances of abuse may prove to be more fruitful. Questions such as, “Has alcohol ever caused you problems or interfered with your life” are more comfortable to answer as opposed to the blunt question, “Are you an alcoholic? Questions regarding substance abuse need to take place in private, and in a non-judgmental, non-threatening fashion.4 Obtaining truthful answers about drug and alcohol use by adolescent patients may be a challenge, especially if a parent is in attendance. The answers always need to be taken with some degree of skepticism. Adolescents who lack home and social support are more likely to have some mental health issues.4
A final component of mental health that needs to be assessed is cognitive status. Patients with all forms of mental illness may be cognitively intact, and therefore able to make decisions regarding their medical care, and therefore able to provide informed consent. Patients with advanced dementia may present to the office and are clearly unable to understand the nature of their dental disease and the nature of the proposed treatment. In such cases, ensuring that the person in attendance is a power of attorney or has been identified as a substitute decision maker is essential. However, there are a number of patients who may have milder forms of dementia that allows them to function quite well in society, but they may lack the cognitive ability to understand the nature of their medical care. All patients merit cognitive testing, whether they carry a psychiatric diagnosis or not.3 The interaction of psychiatric illness and cognition is underscored in Sylvia Nasar’s book on John Nash, ‘A Beautiful Mind”. Nash, a Nobel Prize wining mathematician, demonstrated that he would become too distraught during a significant exacerbation of psychiatric illness to use his full cognitive abilities. Cognition can also be impaired in patients with dementia, delirium and autism. Other medical or surgical conditions such as encephalitis, tumors, trauma or medications can also impair cognition.2 Simple questions of orientation are a good starting point. Being oriented to person, place and time is an important component to the Glasgow Coma Scale. It is important to realize that some patients may be insulted by questions on orientation, and it may be beneficial allow the patient to provide these answers in written form on a questionnaire.
While pharmacology does not provide the only answer to treatment of psychiatric illness, it is the one facet of patient care that can interact with medications used in dentistry and especially, sedation and anesthesia. The main classifications of psychotropic medications include antidepressants, benzodiazepines, mood stabilizers, and antipsychotics.
Drugs used to treat depression may require 6- 8 weeks to achieve a substantial eff
ect, and are effective in up to 80% of patients.5 A number of classes of drugs are available and include selective serotonin reuptake inhibitors (fluoxetine, citalopram, escitalopram, sertraline, paroxetine and fluvoxamine), serotonin-norepinephrine reuptake inhibitors (venlafaxine, duloxetine and desvenlafaxine), tricyclics (amitriptyline, desipramine, nortriptyline and imipramine), monoamine oxidase inhibitors (tranylcypromine and selegiline) and others such as bupropion and mirtazapine. The most commonly prescribed drugs in these classes include the selective serotonin reuptake inhibitors (SSRI’s) and the serotonin-norepinephrine reuptake inhibitors (SNRI’s).6 The tricyclic antidepressants (TCA’s) still have some usefulness, but the side effects make them less attractive than the newer SSRI’s and SNRI’s. The monoamine oxidase inhibitors (MAO-I’s) were the first class of agents used to treat depression.7 The precise mechanism of action of antidepressants is not known, but they appear to act by altering noradrenergic and serotonergic neurotransmission.8 Depression is felt to be due to a lack of these biogenic amines and that efforts to increase neurotransmission will bring about a beneficial effect. The TCA’s tend to exert troublesome autonomic nervous system side effects (largely due to their anticholinergic, antiadrenergic and antihistaminic properties) such as xerostomia, urinary retention, constipation and orthostatic hypotension,8 thus making them less attractive options in the management of depression. TCA’s in overdose proportions also give rise to sinus tachycardia that can progress to ventricular arrhythmias that can be lethal. The MAO-I’s are rarely used because their administration is complicated by side effects such as hypotension, lethality in overdose and lack of simplicity on dosing.8 Patients treated with MAO-I’s must follow a strict tyramine free diet in order to prevent a food-drug interaction that results in severe hypertension.
Abrupt discontinuation of any antidepressant drug is associated with a risk of developing discontinuation syndrome.9 Common features include nausea, abdominal pain, sleep disturbance and irritability. Gradual cessation of the drug generally avoids the problem. With the exception of the MAO-I’s it is appropriate to have patients continue their medications throughout the perioperative period. The SSRI’s and SNRI’s are generally felt to the first line agents in the management of depression due to fewer side effects. Common side effects include insomnia, agitation, headache and nausea. A prominent cause of medication non-compliance with SSRI therapy is drug induced sexual dysfunction.10 Another, more serious potential issue with the use of both SSRI’s and SNRI’s is the risk of serotonin syndrome. Serotonin syndrome is a predictable consequence of excess serotonergic activity in the CNS and periphery. Signs include cognitive effects such as agitation and confusion, autonomic effects including tachycardia and hypertension and somatic effects such as severe twitching and tremors.11 While the mechanisms of the syndrome are incompletely understood, it is felt to be due to drug interactions that result in excess serotonergic activity. Concurrent use of MAO-I’s and the analgesic meperidine can precipitate the syndrome, and therefore meperidine use should be avoided. The use of Tramadol® for analgesia in patients taking SSRI’s has also been associated with serotonin syndrome, and caution should be used when prescribing the analgesic to patients known to be taking SSRI’s.
Another, and perhaps more contentious issue with the antidepressants is the potential for interactions with vasoconstrictors used in local anesthesia.12,13 The benefits of adding a vasoconstrictor to local anesthetic agents are well understood. There is a potential for drug-drug interactions related to local anesthetic formulations and TCA’s. The systemic blood pressure response to the administration of sympathomimetics to patients treated with TCA’s is complex and unpredictable and the inclusion of epinephrine in local anesthesia has been questioned8. The interaction between the two drugs will be affected by the length of time that the patient has been treated with the TCA drug. Chronic administration of these drugs result in decreased sympathetic nervous system transmission due to down regulation of beta-adrenergic receptors.14 Epinephrine use in such patients is generally felt to be safe, although caution should be exercised, and if possible, the blood pressure should be observed after the administration of two or more local anesthetic cartridges.7 Patients who have recently started drug therapy with a TCA will likely be more at risk for an exaggerated response to epinephrine. Ephedrine acts as a direct and indirect sympathomimetic, and will often be used in the emergency management of hypotension that is accompanied with bradycardia. For patients who have been chronically treated with TCA’s, it is felt that ephedrine can be used, but cautiously, and at a lower dose than is customarily suggested.8 The potential for interaction between the MAO-I’s and vasoconstrictors that could result in hypertension can no longer be substantiated, especially in light of evidence provided by Yagiela et al.15 A final consideration for patients taking SSRI’s is their potential to inhibit several hepatic enzymes, especially the CYP2D6 family. This family of enzymes is responsible for demethylating codeine to the active morphine, and hence in patients taking SSRI’s, inadequate pain relief may be experienced. Fluoxetine (Prozac®) and paroxetine (Paxil®) may have the greatest influence on this enzyme.16
The benzodiazepine (BZD’s) class of drugs is often used to manage patients with anxiety disorders. Dentists will often prescribe members of this class of drug to manage anxiety during dental treatment, and they can be used in both oral and intravenous forms. Common to all BZD’s are the anxiolytic, anticonvulsant, sedative, muscle relaxing and amnestic effects. BZD’s appear to produce all of their pharmacologic effects by facilitating the actions of gamma-aminobutyric acid (GABA), the principle inhibitory neurotransmitter in the CNS.17 The most common side effect of the BZD’s is sedation, and will act synergistically with other CNS depressants including alcohol and opioids. Certain drugs in this class, especially diazepam, have long half-lives, and active metabolites, making it important to understand the pharmacokinetics of the drug selected. Oral triazolam is often selected for oral premedication since its metabolites lack activity, and the elimination half-life of the drug is about 2 hours.17 Metabolism of the BZD’s can also be affected alterations in the activity of the cytochrome P450 (CYP3A4) enzyme family. Metabolism of the BZD’s will be inhibited in the presence of macrolide antibiotics (Erythromycin), azole antifungal drugs and calcium channel blockers are known to compete with CYP3A4,17 and therefore should be used with caution as over sedation can result.
The antipsychotic drugs are effective in treating the ‘positive symptoms’ of schizophrenia such as hallucinations and delusions, and the ‘negative symptoms’, which include apathy, social withdrawal and blunted affect.18 All antipsychotic drugs act to block dopamine receptors and specifically, the D2 receptor. Much like the TCA’s, most of antipsychotic drugs have anticholinergic, antihistaminic and sedating properties which can be debilitating. Long-term use of the drugs can also result in severe muscle problems including tardive dyskinesia and acute dystonia.8 Tardive dyskinesia may be seen approximately 20% of patients treated with antipsychotics for greater than a year. Manifestations will include abnormal involuntary movements of the facial and neck muscles, and is unfortunately untreatable. Acute dystonic reactions may be seen in 2% of patients and wi
ll be seen within the first 72 hours of treatment. Manifestations will include acute skeletal muscle rigidity involving the neck, tongue, face and back. Fortunately, acute dystonic reactions are treatable with diphenhydramine.8 Many of the antipsychotic drugs in the phenothiazine class such as chlorpromazine have alpha-adrenergic blockade actions, which results in orthostatic hypotension. Therefore, caution should be exercised when discharging a patient from the dental chair. There does not appear to be an issue with the concurrent use of vasoconstrictors in local anesthesia in this group of patients. Dimenhydrinate, or Gravol® has antihistaminic and antimuscarinic actions should be avoided in patients treated with antipsychotic drugs as it may precipitate delirium.7
Bipolar affective disorder is characterized by swings in mood from deep depression to a manic state. Lithium continues to be the standard treatment for bipolar disorder, but antiepileptic drugs such as valproate and carbamazepine are also often used.19 The main concern associated with the long-term use of lithium is the potential for renal toxicity. The non-steroidal anti-inflammatory drugs (NSAID’s) should be avoided in these patients.8
From the above discussion, it can be appreciated that it is not always easy to identify individuals who may be experiencing significant mental health issues. An open and non-judgmental approach to history taking is essential. Mental health concerns such as substance abuse should always be considered: There is no such thing as the typical substance abuser. It spans all socio-economic levels. If a diagnosis has been made, it is important to question the patient about the response to treatment as well as compliance with any medications. Finally, it is also important to understand the potential for drug interactions that may arise with the medications that may be used in dentistry. OH
Kevin J. McCann, BSc, DDS, FRCD(C), Diplomate, ADSA. Dr. McCann has a private practice in Waterloo, ON. Email:email@example.com
Oral Health welcomes this original article.
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