Bppv Differential Diagnosis

---
name: bppv-differential-diagnosis
description: Distinguishes BPPV from its key mimics at the bedside — postural hypotension, vestibular paroxysmia, vestibular migraine, central positional vertigo, and chronic unilateral vestibular hypofunction — using history, trigger patterns, nystagmus characteristics, and response to treatment. Use when a patient has positional vertigo and you're unsure if it's BPPV, when Dix-Hallpike is atypical, or when the patient has not responded to repositioning maneuvers. Trigger phrases: "is this BPPV or something else", "BPPV not responding to Epley", "atypical positional vertigo", "mimics of BPPV", "positional dizziness differential".
---

# BPPV Differential Diagnosis Checker

> Use this skill when:
> - Positional vertigo is present but Dix-Hallpike is atypical or negative
> - Patient has not responded to repositioning maneuvers after 2–3 attempts
> - Clinical features don't quite fit classic posterior canal BPPV

---

## Step 1 — Confirm the Core BPPV Pattern First

**Classic posterior canal BPPV has ALL of the following:**

| Feature | Expected in BPPV |
|---|---|
| Trigger | Specific head movements — lying down, rolling in bed, looking up, bending forward |
| Duration of each episode | < 1 minute (usually 30–60 seconds) |
| Dix-Hallpike response | Latency 2–20s, upbeat-torsional nystagmus, duration <1 min, fatigues with repetition, severe vertigo |
| Hearing | Normal — no hearing loss, no tinnitus |
| Neurologic exam | Normal |
| Between attacks | Mild imbalance possible; NO sustained dizziness |

> If ANY of the above is atypical → work through the mimics below.

---

## Step 2 — Mimic 1: Postural (Orthostatic) Hypotension

**Key distinguishing features:**

| | BPPV | Postural Hypotension |
|---|---|---|
| Sensation | Vertigo (spinning/tilting) | Near-faint, lightheadedness, "nearly blacking out" |
| Triggered by lying down / rolling in bed | ✅ Yes | ❌ No |
| Triggered by standing up | ❌ Rarely | ✅ Yes — the key trigger |
| Dix-Hallpike nystagmus | Present | Absent |

**Confirm:** Measure BP and pulse lying → standing. Drop ≥20 mmHg systolic = orthostatic hypotension.

> ⚠️ Both can cause dizziness on arising from bed — but postural hypotension is triggered by the act of standing, not by the head position itself.

---

## Step 3 — Mimic 2: Chronic Unilateral Vestibular Hypofunction

**Key distinguishing features:**

| | BPPV | Unilateral Vestibular Hypofunction |
|---|---|---|
| Episode duration | 30–60 seconds | Very brief — 1 to 2 seconds only |
| Trigger | Any positional change (lying, rolling, looking up/down) | Rapid head turns only |
| Looking up / bending forward triggers it | ✅ Yes | ❌ No |
| Dix-Hallpike | Positive (typical pattern) | Usually negative |

> The fleeting 1–2 second duration with rapid head turns is the giveaway for vestibular hypofunction.

---

## Step 4 — Mimic 3: Vestibular Paroxysmia

**Key distinguishing features:**

| | BPPV | Vestibular Paroxysmia |
|---|---|---|
| Episode duration | 30–60 seconds | 1 to several seconds — very brief |
| Frequency | Episodic, often weeks between bouts | Multiple times per day |
| Triggers | Head position changes | Sometimes head turn, sometimes unprovoked |
| MRI finding | Normal | May show neurovascular compression |

> Very brief attacks recurring many times daily → think vestibular paroxysmia, not BPPV. MRI of the posterior fossa is warranted.

---

## Step 5 — Mimic 4: Vestibular Migraine

**Key distinguishing features:**

| | BPPV | Vestibular Migraine |
|---|---|---|
| Episode duration | < 1 minute | Minutes to hours (occasionally seconds) |
| Recurrence pattern | Weeks to months between bouts | More frequent recurrences |
| Associated symptoms | None during attack | Headache, photophobia, phonophobia (may be subtle) |
| Age of onset | Any age, more common >60 | Often younger patients |
| Positional nystagmus | Typical BPPV pattern | Atypical — does not fit BPPV criteria |
| Response to Epley | ✅ Usually resolves | ❌ Does not resolve |

> ⚠️ Vestibular migraine can mimic BPPV closely, including positional provocation. Clues: younger age, recurrences over hours-to-days (not weeks-to-months), migrainous symptoms (even subtle), atypical nystagmus on Dix-Hallpike.

---

## Step 6 — Mimic 5: Central Positional Vertigo

**Key distinguishing features:**

| | BPPV | Central Positional Vertigo |
|---|---|---|
| Nystagmus on Dix-Hallpike | Upbeat-torsional, latency 2–20s, <1 min, fatigues, severe vertigo | Static, persists as long as position maintained; often downbeat; no latency; nonfatiguing |
| Effect of visual fixation on nystagmus | Suppressed | Not suppressed |
| Other neurologic signs | Absent | May be present (ataxia, dysarthria, diplopia) |
| Cause | Otoconia in posterior canal | Cerebellar lesion (especially vermis); demyelination; Chiari malformation |

> 🚨 **Classic central sign:** Downbeat positional nystagmus that is **static** (persists throughout the head-down position, does not fatigue). This needs neuroimaging.
>
> 🚨 **Patients with static positional nystagmus without prior typical BPPV should be investigated for central disease.**

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## Summary Decision Table

| Feature | BPPV | Postural Hypotension | Vestibular Hypofunction | Vestibular Paroxysmia | Vestibular Migraine | Central Positional Vertigo |
|---|---|---|---|---|---|---|
| Duration | 30–60s | Seconds–minutes | 1–2s | 1–several s | Minutes–hours | Persists in position |
| Dix-Hallpike | Typical | Negative | Negative | Variable | Atypical | Atypical/static |
| Hearing loss | No | No | Possible | No | No | Usually no |
| Neurologic signs | No | No | No | No | No | Possible |
| Response to Epley | Yes | N/A | N/A | No | No | No |

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## Clinical Guardrails

- **Non-response to Epley after 2–3 sessions** = reassess the diagnosis. The most common reasons are wrong canal (horizontal or anterior), wrong side, or a mimic — not treatment failure per se.
- **Atypical Dix-Hallpike** (no latency, non-fatiguing, persistent, minimal vertigo, or downbeat nystagmus) = central cause until proven otherwise → MRI brain.
- **Vestibular migraine is underdiagnosed** — ask specifically about headaches, photophobia, or phonophobia during or around dizzy episodes; these may be subtle.
- **Subjective BPPV** (typical history but no nystagmus on exam) — empiric repositioning is reasonable if history is convincing, but other diagnoses should be considered if treatment fails within a few days.

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*Source: Barton JS. "Benign paroxysmal positional vertigo." UpToDate. Last updated Nov 04, 2024.*