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FACT SHEET: Huntington Disease (also known as “HD”, “Huntington’s chorea”, “Huntington chronic progressive hereditary chorea”, and “chronic progressive chorea”)

Date of Publication: October 14, 2020
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Note: Co-morbid diseases/conditions such as bipolar disorder, depression, dementia, seizure disorder, and xerostomia are addressed in detail in separate fact sheets.

Is the initiation of non-invasive dental hygiene procedures* contra-indicated?

  • No, in most circumstances.
  • Yes, if the patient/client displays such a high degree of involuntary movements that safety may be compromised for himself/herself or the dental hygienist during procedures.
  • Yes, if the patient/client displays manic, catatonic, psychotic, or aggressive behaviour that poses a risk to himself/herself or the dental hygienist during procedures (e.g., pronounced distractibility, psychomotor agitation, or disorganized behaviour).

Is medical consult advised?  

  • No, assuming patient/client is already under medical care for HD and such management has been optimized for the stage of the disease.
  • Yes, if Huntington disease is newly suspected.1
  • Yes, if bipolar disorder (e.g., manic behaviour), depression, dementia, or seizure disorder is newly suspected.
  • Yes, if medical management is suspected to be suboptimal for the stage of HD or its complications or co-morbid diseases/conditions (including bipolar disorder, depression, dementia, and seizure disorder). Immediate referral is indicated if suicidality is suspected.
  • Yes, if there is medication non-compliance.
  • Yes, if akathisia2 or tardive dyskinesia is newly suspected in patients/clients taking antipsychotic medications.
  • Yes, if severe xerostomia is suspected to be related to antipsychotic or antidepressant use (which may improve if an alternative antipsychotic or antidepressant is a consideration).

Is the initiation of invasive dental hygiene procedures contra-indicated?**

  • No, in many circumstances.   
  • Yes, if the patient/client displays such a high degree of involuntary movements that safety may be compromised for himself/herself or the dental hygienist during procedures.
  • Yes, if the patient/client displays manic, catatonic, psychotic, or aggressive behaviour that poses a risk to himself/herself or the dental hygienist during procedures (e.g., pronounced distractibility, psychomotor agitation, or disorganized behaviour).

Is medical consult advised? 

  • See above. Additionally, yes, if patient/client has a history suggestive of a need for pre-procedure medication for calming, involuntary muscle movement control, seizure control, or other behavioural challenges 

Is medical clearance required? 

  • Yes, if the patient/client displays signs/symptoms that may affect the appropriateness or safety of procedures, including potential exacerbation by procedures. In particular, problems with swallowing, choking, and involuntary muscle movements should be assessed.
  • Yes, if there is significant risk of seizure.
  • Yes, if severe leukopenia (i.e., reduced white blood cell count, and hence immunosuppression), agranulocytosis, or thrombocytopenia (i.e., reduced platelet count, and hence increased bleeding risk) is suspected with mood-stabilizing medication (particularly carbamazepine and valproic acid), antidepressant medication (particularly tricyclic antidepressants)3, or antipsychotic medication (particularly quetiapine, clozapine, and the phenothiazine class) use. [This would be a rare situation in the dental hygiene office setting.]

Is antibiotic prophylaxis required?  

  • No (in the absence of immunosuppression).

Is postponing treatment advised?

  • No, assuming the dental hygiene office can appropriately accommodate special needs of the patient/client with HD (e.g., wheelchair in clinic room).
  • Yes, if patient/client displays signs/symptoms (e.g., high degree of involuntary muscle movements) that may affect safety of procedures for which appropriate mitigation cannot be made.
  • Yes, if the patient/client exhibits manic, catatonic, psychotic, or aggressive behaviour that may pose risk during, or cause inability to perform, procedures, in which case medical intervention is first needed.
  • Yes, if co-morbid seizure disorder needs to be medically addressed prior to dental hygiene treatment.
  • Yes, if certain oral pathology — such as tooth fractures — needs to be dentally addressed prior to dental hygiene treatment.
  • Yes, if patient/client is medically unstable. Malignant neuroleptic syndrome in the operatory is a medical emergency, which necessitates cessation of dental/dental hygiene treatment, immediate contact with emergency medical services, and supportive management pending hospital transfer.4
  • Yes, if medical clearance is pending regarding possible immunosuppression or thrombocytopenia associated with mood-stabilizer, antidepressant, or antipsychotic medication use.
  • Yes, if patient/client has not complied with pre-medication (e.g., sedative), when indicated and as directed by the prescribing physician.
  • Yes, if severe signs/symptoms of depression exist (in which case attainment of better depression control may be indicated before attempting elective dental hygiene procedures).

Oral management implications

  • Each patient/client with HD is affected differently, and the disease’s manifestations change over time. Therefore, the therapeutic relationship is enhanced by getting to know the patient/client over time and establishing trust.
  • Over time, HD usually impairs cognition, including judgment. Consequently, the oral health team should determine whether the patient/client is able to make rational decisions regarding care and, if indicated, who the substitute decision-maker is. Treatment planning may often involve input and permission from a family member.
  • The dental hygienist should bear in mind that many processes are slowed in persons with Huntington disease. Longer appointments should be booked, ideally at the best time of the day for the patient/client.
  • Speech may be unclear, and thus expressive language is affected. However, receptive language is not affected to the same degree; someone with HD can hear and usually understand what is being said. Always assume (unless told or from experience) that the patient/client understands and can communicate. The dental hygienist should speak clearly and allow enough time for the patient/client to comprehend and respond. Communication can become frustrating and exhausting for someone with HD.  
  • Given motor impairment and difficulty in performing adequate self-care, frequent oral healthcare visits are indicated to maintain good oral health and preserve natural dentition for as long as possible.
  • An office space that is accessible can help with gait and balance issues. “White noise”, music, or noise-reducing headphones can be offered to reduce distractions. In advanced disease, it may be helpful to have the caregiver in the room (within sight and holding hand if desired).  
  • Treatment modifications during the dental hygiene visit are increasingly required as the patient/client’s disease progresses. For example, wheelchair transfers may be required. Positioning the back of the dental chair more upright and limiting the use of ultrasonic instrumentation may be indicated to reduce difficulty in swallowing and risk of choking. Other team members may be needed to assist with suctioning, retraction, and stabilization.
  • Extra-oral fulcrum for hand positioning may assist with scaling. A rubber mouth prop or a mouth clamp may enhance patient/client comfort. Bite blocks may assist patients/clients with muscle weakness that results in difficulty keeping the mouth open. Bear in mind that a person with HD may not be able to open his/her mouth widely.
  • Risk of aspiration or micro-aspiration increases as the disease progresses.
  • For patients/clients with a high degree of involuntary movements, dental and dental hygiene treatment may need to occur in a specialized medical facility using general anaesthetic. Oral sedatives or intravenous conscious sedation may be a consideration for some patients/clients. 
  • Provision of oral self-care education to patients/clients with HD and their caregivers is very important. Dexterity, cognition, and motivation should be considered when customizing a care plan. Apathy, a symptom of the disease, means that personal care is not always an individual’s priority. A wide array of dental care devices, both manual and powered, should be considered over time. Oral hygiene aids include enlarged and /or weighted handles/grips, wrist weight cuffs, and mouth angle expanders. 
  • A preventive dental care regime should be implemented early and maintained as the disease progresses, including consideration of high fluoride toothpaste and/or fluoride mouthwashes. An electric toothbrush can be helpful (if vibration and noise are tolerated). Dipping a tooth brush into mouthwash (instead of using toothpaste) can also be effective and easier for some patients/clients. Water pics and air flossers may be alternatives to regular floss for some patients/clients.
  • Because dysphagia worsens over time, a suction toothbrush system can be considered to help remove debris and fluid from the mouth. Toothpaste that is non-foaming (e.g., free of sodium lauryl sulphate) can reduce risk of aspiration.    
  • Over-the-counter saliva substitutes can ease xerostomia caused by certain prescribed medications. However, as HD progresses and patients/clients have difficulty swallowing, caution should be exercised when recommending mouth rinses for xerostomia, because this can be a choking hazard.
  • Some prescribed medications result in more saliva production and increase the risk of aspiration. In this situation, the patient/client’s neurologist should be consulted for possible treatment for hypersalivation.
  • Dentures should be checked regularly, because progression of HD can affect fit and comfort.
  • Because the high energy diet often required for patients/clients with HD tends to be highly cariogenic, partial mitigation of the adverse oral effects may be achieved by engagement with a registered dietician.   
  • Recurrent lip trauma from choreic mouth movements (i.e., involuntary biting) may be addressed (if appropriate and safe) by a mouthguard, or by extractions if necessary.

Oral manifestations

  • While there are no innate dental features of HD that make an affected individual more susceptible to dental caries or periodontal disease, patients/clients with Huntington disease do have impaired oral health status compared to their peers without HD. This includes more missing and decayed teeth as well as fewer sound and restored teeth. Contributing factors include nutritional influences, percutaneous endoscopic gastrostomy (PEG), medication, oral hygiene, and access to and provision of oral healthcare.  
  • Other oral manifestations associated with HD include:
    • inability to open the mouth widely
    • dysphagia (difficulty swallowing)
    • difficultly speaking and slurred speech
    • bruxism
    • oral trauma (e.g., biting of lips and cheeks) secondary to choreic mouth movements
    • oral trauma (e.g., broken teeth and other facial injuries) secondary to falls 
  • Xerostomia commonly results from reduced salivary flow caused by antipsychotic and antidepressant medications, with attendant discomfort and risk of caries. Deutetrabenazine (used for the treatment of chorea) can also cause dry mouth.
  • Gingival enlargement and/or glossitis can result from use of anticonvulsants.
  • Mask-like face, sore throat, and difficulty with swallowing are side effects of tetrabenazine (used for the treatment of chorea). Mask-like face, as well as slurred speech, can result from use of deutetrabenazine.

Related signs and symptoms

  • Huntington disease is an autosomal dominant inherited disease that causes progressive degeneration of nerve cells in the brain. This neurodegeneration results in movement, cognitive, and psychiatric disorders, ultimately culminating in death. There is no known cure, and there is no definitive treatment.5
  • While signs/symptoms of HD can develop at any time, they typically first appear between ages 30 and 50 years. If the condition manifests before age 20 years (which occurs in 10% of HD cases), it is known as juvenile Huntingdon disease; signs/symptoms may be somewhat different from the adult-onset form, and the disease tends to progress more quickly.6
  • Every child of a person with HD has a 50% chance of inheriting the gene that ultimately causes the disease. Due to the nature of the underlying genetic mutation, through successive generations a person in an affected family is at higher risk for developing the disease earlier in life.  
  • About 4,700 Canadians currently live with HD, with another 14,000 at 50% risk of developing HD. 
  • HD has a wide spectrum of signs/symptoms, and which ones appear first vary greatly from person to person. Similarly, which signs/symptoms predominate or have the greatest effect on functional ability vary over the course of the disease.
  • In aggregate, the various manifestations of HD impact, over time, the patient/client’s ability to work, perform activities of daily living, communicate, and live independently. However, with the exception of the juvenile form, HD tends to progress slowly. The time from disease emergence to death is usually about 10 to 30 years; in juvenile HD, death typically results within 10 years after the disease first manifests.
  • Movement problems include impairments in voluntary movements as well as involuntary movement problems. Manifestations include:
    • chorea (involuntary writhing and jerking movements)
    • muscle dysfunction, such as rigidity and dystonia7
    • impaired posture, gait, and balance
    • slow or abnormal eye movements
  • Cognitive problems include:
    • difficulty in learning new information
    • slowness in processing thoughts or “finding” words
    • difficulty in prioritizing, organizing, and/or focusing on tasks
    • impaired thinking and judgment
    • forgetfulness
    • lack of awareness of one’s abilities and behaviours
    • lack of flexibility or perseveration (i.e., tendency to get stuck on a thought, action, or behaviour)
    • lack of impulse control that can result in acting without thinking, outbursts, and sexual promiscuity
  • Psychiatric problems include:
  • Weight loss is common as the disease progresses.
  • Although progression of the disease varies between patients/clients, HD generally occurs in three stages: early, middle, and late. Each stage of the disease lasts about 5 to 6 years, leading to an average life expectancy of 15 to 20 years after onset of signs/symptoms. 
  • Early stage disease tends to start as minor changes in physical coordination and possible chorea. Apathy, irritability, impaired thinking, depression, delusions, hallucinations, agitation, and anxiety also tend to occur. In some cases, cognitive or psychiatric impairments may appear many years before motor signs appear. The affected person is unable to maintain his/her previous level of activity. 
  • In the middle stage, the patient/client’s movements become more difficult to control, and chorea may become more evident. Hindered manual dexterity is problematic, and prolonged muscle contractures of neck, face, and back may occur. Difficulties with eating, swallowing, speech, and ambulation may require occupational and/or physical therapy. Toilet requirements become increasingly difficult, often requiring the use of diapers. 
  • In late stage disease, the patient/client is unable to speak or walk, although some affected persons may still be able to understand language, communicate emotion, and recognize people. Chorea may be severe or cease altogether. Other characteristics include bradykinesia (difficulty starting or continuing movements), hypertonia (excessive tone of skeletal muscles, which includes increased resistance of muscle to passive stretching), profound weight loss (due to high caloric metabolism associated with excessive movement), and dementia. The patient/client requires around-the-clock care, particularly for nutrition and hydration. Dysphagia means that choking is a major hazard.
  • Malignant neuroleptic syndrome is a rare but potentially life-threatening complication of antipsychotic drugs. It combines hyperthermia, autonomic dysfunction, and extrapyramidal dysfunction. Signs/symptoms include tachycardia, dyspnea, labile blood pressure, tremors, muscle rigidity, catatonic behaviour, dystonia, and marked elevation of temperature (up to 41º C).
  • Death usually results from secondary complications of HD, such as inability to swallow, choking, pneumonia, heart failure, or injuries related to falls.

References and sources of more detailed information


Date: July 6, 2020
Revised:


FOOTNOTES

1 Genetic testing for HD has been available since 1993. Diagnosis and assessment also involve neurological examination, neuropsychological testing, psychiatric evaluation, and brain imaging.
2 akathisia = extreme motor restlessness
3 Selective serotonin reuptake inhibitors (SSRIs, such as citalopram, escitalopram, sertraline, and fluoxetine), and not tricyclic antidepressants (TCAs, such as amitriptyline, nortriptyline, imipramine, and doxepin), are generally considered first-line therapy for depression in patients/clients with Huntington disease
4 Management involves stopping all neuroleptic (i.e., antipsychotic) medications, body cooling, rehydration, and treatment with bromocriptine.
5 Due to the complexity of the disease, a multidisciplinary approach to management (including primary care physician, neurologist, psychiatrist, occupational therapist, physiotherapist, dietician, speech/language therapist, and social worker) is indicated. Medications are used to treat the signs and symptoms of HD, but they do not prevent the physical, mental, and behavioural decline. Tetrabenazine, deutetrabenazine, and certain antipsychotic drugs (e.g., haloperidol and fluphenazine) help control choreic movements; antidepressant drugs (e.g., citalopram, escitalopram, sertraline, and fluoxetine) combat depression; antipsychotic drugs (e.g., quetiapine, risperidone, and olanzapine) reduce delusions, hallucinations, and uncontrolled (and sometimes violent) outbursts; and mood-stabilizer drugs (e.g., anticonvulsants such as divalproex, carbamazepine, and lamotrigine) prevent the highs and lows associated with bipolar disorder.
6 In juvenile HD, early presenting problems include behavioural changes (such as difficulty paying attention and rapid drop-off in school performance) and physical changes (including rigid and contracted muscles that affect gait, tremors or slight involuntary movements, frequent falls, clumsiness, and seizures). Compared with adult HD, seizures and rigidity are more common, and chorea is less common.
7 Dystonia is sustained or repetitive involuntary muscle contractures.


* Includes oral hygiene instruction, fitting a mouth guard, taking an impression, etc.
** Ontario Regulation 501/07 made under the Dental Hygiene Act, 1991. Invasive dental hygiene procedures are scaling teeth and root planing, including curetting surrounding tissue.