### Date : 2024-06-24 12:32 ### Topic : Head Impulse Test (Head Thrust Test) #medicine #ENT #dizziness ---- ### Head Thrust Test (Head Impulse Test) The **Head Thrust Test**, also known as the **Head Impulse Test (HIT)**, is a clinical examination used to assess the ==function of the vestibulo-ocular reflex (VOR)==, which is critical for maintaining stable vision during rapid head movements. It is particularly useful for diagnosing peripheral vestibular disorders, such as [[Vestibular Neuritis]] or labyrinthitis. <iframe title="Head Impulse Test | Peripheral Vestibular Dysfunction" src="https://www.youtube.com/embed/DrA4ERU2aG8?feature=oembed" height="113" width="200" allowfullscreen="" allow="fullscreen" style="aspect-ratio: 1.76991 / 1; width: 100%; height: 100%;"></iframe> ### Purpose of the Head Thrust Test - **Assess Vestibular Function:** To evaluate the function of the semicircular canals and the vestibular nerve. - **Identify Vestibular Hypofunction:** To detect unilateral or bilateral vestibular deficits. - **Differential Diagnosis:** Helps distinguish between central and peripheral causes of vertigo. ### Indications - **Patients with Vertigo:** Especially those with acute, prolonged vertigo. - **Unilateral Hearing Loss:** To assess for associated vestibular dysfunction. - **Balance Disorders:** To investigate the cause of balance issues and dizziness. ### Procedure **1. Patient Preparation:** - The patient is seated comfortably. - The examiner should explain the procedure to the patient to ensure they understand and can cooperate. - The patient is asked to keep their eyes focused on a fixed target, typically the examiner's nose or a specific point on the wall. **2. Performing the Test:** - The examiner holds the patient's head firmly with both hands. - The patient's head is tilted slightly forward (about 30 degrees) to align the horizontal semicircular canals. - The examiner then rapidly moves the patient's head to one side and then back to the center, and repeats this to the other side. Each movement should be quick and unpredictable. **3. Observing the Eyes:** - The examiner closely observes the patient's eyes during the rapid head movements. - **Normal Response:** The eyes remain fixed on the target (indicating a functioning VOR). - **Abnormal Response:** The eyes make a corrective saccade (a quick, corrective eye movement) back to the target after the head movement, indicating a vestibular deficit on the side to which the head was turned. ### Interpretation of Results **Normal Result:** - The eyes stay locked on the target without needing corrective movements, indicating intact VOR and normal vestibular function. **Abnormal Result (Positive Head Thrust Test):** - **Corrective Saccades:** Presence of corrective saccades when the head is turned to the side indicates a vestibular hypofunction on that side. - **Rightward Thrust:** If corrective saccades are observed with a rightward head thrust, it suggests right-sided vestibular hypofunction. - **Leftward Thrust:** If corrective saccades are observed with a leftward head thrust, it suggests left-sided vestibular hypofunction. **Unilateral vs. Bilateral Deficits:** - **Unilateral Vestibular Deficit:** Corrective saccades observed only on one side. - **Bilateral Vestibular Deficit:** Corrective saccades observed on both sides. ### Example Case Study **Patient Profile:** - **Name:** Jee Hoon Ju - **Age:** 45 - **Occupation:** Office Worker **Medical History:** - Complaints of acute onset vertigo and imbalance for the past week. - No significant past medical history of similar episodes. **Clinical Evaluation:** - **Procedure:** Performed the Head Thrust Test with Jee Hoon Ju seated and focusing on the examiner's nose. - **Observation:** Corrective saccades were observed when the head was rapidly turned to the right but not to the left. **Diagnosis:** The presence of corrective saccades with rightward head thrust suggests right-sided vestibular hypofunction, likely due to a peripheral vestibular disorder such as **vestibular neuritis.** ### Management 1. **Vestibular Rehabilitation Therapy (VRT):** - Customized exercises to improve balance and compensate for vestibular deficits. 2. **Medications:** - **Vestibular Suppressants:** Short-term use for symptom relief (e.g., meclizine, diazepam). - **[[Antiemetics]]:** To control nausea and vomiting. 3. **Follow-Up:** - Regular follow-up to monitor progress and adjust rehabilitation exercises. ### Conclusion The Head Thrust Test is a simple, yet effective clinical tool for assessing vestibular function and diagnosing vestibular deficits. By evaluating the vestibulo-ocular reflex through rapid head movements, healthcare providers can identify unilateral or bilateral vestibular hypofunction and guide appropriate management and rehabilitation strategies for patients with vertigo and balance disorders.