The Neurology confusions that cost the most Step 1 points

Neurology look-alikes cost points because the same symptom can appear in more than one condition. For each pair, focus on the one clue that separates the two, then watch for the common trap.

Myasthenia gravis vs Lambert-Eaton syndrome

Both can cause proximal weakness. Myasthenia gravis causes fluctuating ocular or bulbar weakness that worsens with repeated use and involves postsynaptic targets. Lambert-Eaton syndrome involves presynaptic targets and causes proximal leg weakness with autonomic symptoms and brief improvement after contraction. Use the direction of fatigability to separate them: worse with use means myasthenia gravis, while post-exercise facilitation suggests Lambert-Eaton syndrome.

Myasthenia gravis vs Lambert-Eaton syndrome MG worsens with use and is postsynaptic; Lambert-Eaton has post-exercise facilitation and is presynaptic. Open the comparison and video →

Multiple sclerosis vs Neuromyelitis optica

Both can involve optic neuritis. Multiple sclerosis causes relapsing CNS deficits separated in time and space, while neuromyelitis optica causes severe optic-spinal attacks associated with aquaporin-4 autoimmunity. A longitudinally extensive spinal cord lesion spanning three or more vertebral segments shifts the answer toward neuromyelitis optica. Before calling an atypical lesion pattern multiple sclerosis, check for long cord lesions and AQP4 clues.

Multiple sclerosis vs Neuromyelitis optica MS is multifocal CNS demyelination; NMO is optic-spinal disease with AQP4 association and long cord lesions. Open the comparison and video →

Ischemic stroke vs Hemorrhagic stroke

Both can present with a sudden focal neurologic deficit. Ischemic stroke comes from arterial occlusion and may have a normal early noncontrast CT, while hemorrhagic stroke comes from vessel rupture and shows hyperdense blood on CT. Headache, vomiting, depressed consciousness, or very high blood pressure can suggest hemorrhage, but bedside findings do not reliably separate the two. Get a noncontrast head CT before thrombolysis because treatment for ischemia is unsafe until hemorrhage is excluded.

Ischemic stroke vs Hemorrhagic stroke Ischemic stroke: deficit with a normal early noncontrast CT; hemorrhagic stroke: deficit with headache, vomiting, and hyperdense blood on CT. Open the comparison and video →

Bacterial meningitis vs Viral meningitis

Both can cause meningeal symptoms. Bacterial meningitis usually has neutrophilic CSF with low glucose and high protein, while viral meningitis usually has lymphocytic CSF with normal glucose and moderate protein elevation. The trap is that partially treated bacterial meningitis can become lymphocyte-predominant within hours of an antibiotic dose. Read cell type, glucose, protein, and the CSF-to-serum glucose ratio together because a ratio under 0.4 keeps bacterial meningitis on the list regardless of cell predominance.

Bacterial meningitis vs Viral meningitis Bacterial CSF is neutrophilic with low glucose; viral CSF is lymphocytic with normal glucose. Open the comparison and video →

BPPV vs Meniere disease

Both cause vertigo. BPPV causes seconds-long episodes triggered by head-position changes without hearing loss, while Meniere disease causes recurrent spontaneous episodes with fluctuating hearing loss, tinnitus, and aural fullness. The trap is vestibular neuritis, which causes days-long postviral vertigo without hearing loss. Separate these conditions by writing down the duration, trigger, and hearing symptoms before choosing an answer.

BPPV vs Meniere disease BPPV: seconds of position-triggered vertigo with normal hearing; Meniere: episodic vertigo with hearing loss, tinnitus, and aural fullness. Open the comparison and video →

Parkinson disease vs Essential tremor

Both can present with tremor, especially in an older person. Parkinson disease causes an asymmetric resting tremor with bradykinesia, while essential tremor causes a bilateral symmetric action or postural tremor without bradykinesia. Tremor and older age alone are not enough to identify Parkinson disease. Classify the tremor by its timing and symmetry, then look for bradykinesia.

Parkinson disease vs Essential tremor Parkinson tremor is resting plus bradykinesia; essential tremor is action/postural without bradykinesia. Open the comparison and video →

Upper motor neuron lesion vs Lower motor neuron lesion

Both can cause weakness, so weakness alone does not localize the lesion. An upper motor neuron lesion causes spasticity, hyperreflexia, increased tone, and an upgoing Babinski sign, while a lower motor neuron lesion causes flaccidity, hyporeflexia, atrophy, and fasciculations. The trap is that both types of signs can coexist, as in ALS or a spinal cord lesion. Check tone, reflexes, atrophy, fasciculations, and whether upper and lower motor neuron signs appear together before labeling the weakness.

Upper motor neuron lesion vs Lower motor neuron lesion UMN lesion: spastic weakness, hyperreflexia, upgoing Babinski, no atrophy; LMN lesion: flaccid weakness, hyporeflexia, atrophy, fasciculations. Open the comparison and video →

HSV encephalitis vs Bacterial meningitis

Both can cause fever and headache. HSV encephalitis involves brain parenchyma and points toward early altered behavior, personality change, seizures, focal deficits, or temporal lobe MRI changes. Bacterial meningitis involves the meninges and points toward neck stiffness with neutrophilic CSF, low glucose, and high protein. When cortical signs such as personality change, aphasia, focal seizures, or hemiparesis dominate, treat the presentation as encephalitis rather than simple meningitis.

HSV encephalitis vs Bacterial meningitis HSV encephalitis: fever with cortical signs and temporal lobe MRI changes; bacterial meningitis: fever with neck stiffness and neutrophilic CSF. Open the comparison and video →

Quick self-test

Name the diagnosis from the clue, then tap to check.

1. Brief vertigo triggered by head position changes without hearing loss.

   BPPV · BPPV vs Meniere disease

2. Recurrent vertigo with fluctuating hearing loss, tinnitus, and aural fullness.

   Meniere disease · BPPV vs Meniere disease

3. Resting tremor with bradykinesia, rigidity, shuffling gait, and postural instability.

   Parkinson disease · Parkinson disease vs Essential tremor

4. Fever with early altered behavior, personality change, seizures, focal deficits, and possible temporal lobe involvement.

   HSV encephalitis · HSV encephalitis vs Bacterial meningitis

5. Severe optic neuritis plus longitudinally extensive transverse myelitis, often with area postrema symptoms.

   Neuromyelitis optica · Multiple sclerosis vs Neuromyelitis optica

6. Relapsing CNS deficits separated in time and space, often with optic neuritis, internuclear ophthalmoplegia, or periventricular lesions.

   Multiple sclerosis · Multiple sclerosis vs Neuromyelitis optica

7. Bleeding with severe headache, vomiting, depressed consciousness, or very high blood pressure.

   Hemorrhagic stroke · Ischemic stroke vs Hemorrhagic stroke

8. Sudden focal deficit from vessel occlusion, often without severe headache.

   Ischemic stroke · Ischemic stroke vs Hemorrhagic stroke

9. Meningeal symptoms with lymphocytic CSF, normal glucose, and moderate protein elevation.

   Viral meningitis · Bacterial meningitis vs Viral meningitis

10. Fever, headache, neck stiffness, neutrophilic CSF, low glucose, and high protein.

    Bacterial meningitis · HSV encephalitis vs Bacterial meningitis

11. Proximal leg weakness with autonomic symptoms, small-cell lung cancer association, and post-exercise facilitation of strength or reflexes.

    Lambert-Eaton syndrome · Myasthenia gravis vs Lambert-Eaton syndrome

12. Fever, neck stiffness, toxic appearance, neutrophilic CSF, low glucose, and high protein.

    Bacterial meningitis · Bacterial meningitis vs Viral meningitis

13. Weakness with spasticity, hyperreflexia, increased tone, and Babinski sign.

    Upper motor neuron lesion · Upper motor neuron lesion vs Lower motor neuron lesion

14. Weakness with flaccidity, hyporeflexia, fasciculations, and muscle atrophy.

    Lower motor neuron lesion · Upper motor neuron lesion vs Lower motor neuron lesion

15. Fluctuating ocular or bulbar weakness that worsens with repeated use.

    Myasthenia gravis · Myasthenia gravis vs Lambert-Eaton syndrome

How to make these stick

Practice each pair with fresh questions until you recognize the separating clue automatically. Keep returning to any pair that still makes you pause.