Vertigo (Peripheral vs. Central Framework)
Vertigo is defined as the false perception of rotational or directional movement. For board examinations, the absolute priority is mapping a clinical vignette to either a peripheral vestibular dysfunction or a life-threatening central nervous system lesion.
Diagnostic Differentiation
| Clinical Feature | Peripheral Etiology | Central Etiology |
|---|---|---|
| Onset & Intensity | Sudden onset; severe, intense, episodic spinning sensation. | Gradual or sudden onset; milder, constant, unyielding imbalance. |
| Spontaneous Nystagmus | **Unidirectional**; horizontal/torsional; suppressed completely by visual fixation. | **Bidirectional** or multi-directional; **purely vertical** (up/downbeat) or torsional; unaffected by fixation. |
| Auditory Symptoms | Frequently present (tinnitus, fluctuating or progressive hearing loss). | Typically absent (except in rare cases of AICA territory strokes). |
| Neurological Deficits | Absent (except for downstream autonomic symptoms like nausea/vomiting). | **Present** (ataxia, dysmetria, diplopia, dysarthria, focal motor/sensory deficits). |
| HINTS Exam Findings | Abnormal Head Impulse test; Unidirectional nystagmus; No Skew deviation. | Normal Head Impulse test; Direction-changing nystagmus; **Skew deviation present**. |
High-Yield Disease Profiles
1. Peripheral Modalities
- Benign Paroxysmal Positional Vertigo (BPPV): Brief paroxysms of intense vertigo triggered exclusively by head movement (e.g., rolling over in bed). Lasts **less than 1 minute**. Diagnosed with the *Dix-Hallpike maneuver* and treated via the *Epley maneuver*.
- Ménière’s Disease (Endolymphatic Hydrops): Recurrent, spontaneous episodes lasting **20 minutes to several hours**. Defined by the pathognomonic triad: episodic vertigo, tinnitus, and low-frequency SNHL, usually accompanied by a sensation of aural fullness. Driven by a breakdown in endolymph production/resorption.
- Vestibular Neuritis vs. Labyrinthitis: Prolonged, severe vertigo lasting **days**.
- *Vestibular Neuritis:* Post-viral inflammation of the vestibular nerve; auditory function is normal.
- *Labyrinthitis:* Inflammation involves both the cochlear and vestibular divisions; presents with concurrent acute SNHL.
2. Central Modalities
- Vestibular Migraine: Episodic central vertigo strongly linked to migraine triggers, photo/phonophobia, or visual auras. Can mimic peripheral syndromes but displays central tracking variations.
- Wallenberg Syndrome (Lateral Medullary Syndrome): Occlusion of the PICA or vertebral artery. Triggers vertigo, nystagmus, ipsilateral Horner’s syndrome, ipsilateral ataxia, dysphagia/dysarthria (nucleus ambiguus), and contralateral loss of pain/temperature from the body.
- Acoustic Neuroma (Vestibular Schwannoma): Benign tumor of the schwann cells lining CN VIII at the CP angle. Causes progressive asymmetric SNHL, tinnitus, and late-onset central equilibrium imbalance rather than acute spinning spells.