Link Between Mild Traumatic Brain Injury (mTBI) and Xerostomia (Dry Mouth)
There is currently no established direct link between mild traumatic brain injury (mTBI)/concussion and xerostomia (dry mouth) symptoms in the available medical evidence and guidelines.
Understanding mTBI and Its Symptoms
Mild traumatic brain injury (mTBI) is defined as an acute brain injury resulting from mechanical energy to the head with one or more of the following:
- Confusion or disorientation
- Loss of consciousness for 30 minutes or less
- Post-traumatic amnesia for less than 24 hours
- Transient neurological abnormalities
- Glasgow Coma Scale (GCS) score of 13-15 1
Common mTBI Symptoms
The most frequently reported symptoms following mTBI include:
- Headache (83% of patients)
- Fatigue (80%)
- Difficulty thinking (73%)
- Irritability (73%)
- Dizziness (70%)
- Memory problems (70%) 2
These symptoms are part of what may be termed the "early phase post-traumatic disorder" that typically resolves within days to weeks 3.
Post-Concussion Syndrome and Symptom Patterns
In some patients, mTBI can lead to a "late phase post-traumatic disorder" with prolonged symptoms lasting months to years 3. This condition, often called post-concussion syndrome (PCS), affects approximately 54.5% of patients with mTBI 4.
The American College of Neurology notes that up to 15% of patients with mild TBI may have compromised function one year after injury, and up to 50% may not recover pre-injury levels of health and well-being within 6 months 5.
Symptom Bothersomeness and Management
Research shows that patients with mTBI report an average of 19 symptoms (compared to 6 in non-injured individuals), and there is a significant relationship between being bothered by symptoms and the use of symptom management strategies 2.
Xerostomia (Dry Mouth) and mTBI
While the current guidelines and research on mTBI extensively document various neurological, cognitive, and somatic symptoms, there is no specific mention of xerostomia or dry mouth as a direct consequence of mTBI in the available evidence 1, 5.
Possible Mechanisms (Theoretical)
Although not directly established in the literature, there are potential indirect mechanisms that could theoretically connect mTBI to dry mouth:
Autonomic Nervous System Dysfunction: TBI can affect autonomic regulation, which controls salivary gland function.
Medication Side Effects: Medications prescribed for post-concussion symptoms (such as certain pain medications, antidepressants, or anti-anxiety medications) may cause dry mouth as a side effect.
Dehydration: Altered thirst perception or behavioral changes following mTBI might lead to reduced fluid intake.
Clinical Implications
For patients presenting with both mTBI and dry mouth symptoms:
- Evaluate for other causes of xerostomia, including medications, dehydration, anxiety, or pre-existing conditions
- Consider the timing of symptom onset in relation to the injury
- Assess for medication side effects if the patient is being treated for other post-concussion symptoms
- Manage dry mouth symptomatically with hydration, salivary substitutes, or other appropriate interventions
Diagnostic Considerations
It's important to note that mTBI diagnosis is often challenging, particularly at the milder end of the spectrum 3. A study found that 69.7% of patients involved in motor vehicle collisions had presumed mTBI, but an acute care diagnosis was made in only 39.1% of cases 4.
When evaluating patients with persistent symptoms after head injury, including unusual symptoms like dry mouth, clinicians should:
- Conduct a thorough assessment of the injury mechanism and immediate symptoms
- Use standardized symptom scales to document the full range of complaints
- Consider both direct neurological effects and indirect consequences of injury
Conclusion
While xerostomia is not currently recognized as a typical symptom of mTBI in clinical guidelines or research, patients with mTBI often experience a wide range of symptoms that may not be fully captured in standardized assessments. For patients presenting with both mTBI and dry mouth, clinicians should evaluate for other causes while acknowledging the complex and varied presentation of post-concussion symptoms.