Differential Diagnosis for Positive HINTS Exam

The HINTS (Head Impulse, Nystagmus, Test of Skew) exam is a bedside assessment tool used to evaluate patients with suspected vestibular disorders, particularly in the context of acute vertigo. A positive head impulse test, nystagmus with a horizontal component, and no correction on the test of skew suggest a peripheral vestibular cause. Here's a differential diagnosis based on the provided findings:

• Single Most Likely Diagnosis

  • Acute Vestibular Neuritis (Labyrinthitis): This condition is characterized by inflammation of the inner ear, leading to vestibular dysfunction. The positive head impulse test indicates a problem with the vestibulo-ocular reflex, which is consistent with vestibular neuritis. The presence of nystagmus with a fast component towards the right suggests an imbalance in vestibular input, which can occur in labyrinthitis affecting the right ear.

• Other Likely Diagnoses

  • Benign Paroxysmal Positional Vertigo (BPPV): Although BPPV typically presents with vertigo triggered by specific head movements and has a more episodic nature, some variants can present with continuous vertigo and nystagmus. However, the lack of correction on the test of skew and the nature of the nystagmus might be less typical for BPPV.
  • Labyrinthine Concussion: If there's a history of head trauma, a labyrinthine concussion could be considered, as it can cause similar symptoms due to injury to the inner ear structures.

• Do Not Miss Diagnoses

  • Posterior Circulation Stroke: Although less likely given the peripheral signs on the HINTS exam, a stroke in the posterior circulation (e.g., lateral medullary syndrome or cerebellar stroke) can sometimes mimic peripheral vestibular disorders. The absence of central signs (e.g., skew deviation that corrects with cover-uncover testing) makes this less likely, but given the potential severity, it's crucial not to miss this diagnosis.
  • Multiple Sclerosis: In rare cases, multiple sclerosis can present with vertigo and nystagmus due to central nervous system demyelination affecting vestibular pathways. However, this would typically be accompanied by other neurological signs.

• Rare Diagnoses

  • Vestibular Paroxysmia: A rare condition characterized by episodic vertigo due to neurovascular compression of the vestibulocochlear nerve. It might present with nystagmus but is less likely to cause a consistently positive head impulse test.
  • Superior Semicircular Canal Dehiscence: This condition involves an abnormal opening in the bone overlying the superior semicircular canal, leading to vestibular and auditory symptoms. While it can cause vertigo and nystagmus, the specific findings on the HINTS exam would be atypical for this diagnosis.