Thanks to Rebecca Wang for presenting a cool case of a middle aged man who presented with dizziness/vertigo and was found to have demyelinating brain lesions, felt to be MS vs NMO.
Differentiating between dizziness and true ‘room spinning’ or vertigo is important. You can categorize the complaint of dizziness into pre-syncope, disequilibrium, lightheadedness and true vertigo (which should be accompanied by the ‘room spinning’ sensation).
Questions to ask when investigating vertigo
- How long the vertigo has been going on (longer = more concerning for central)
- Things that provoke the symptoms (changes in head position, head trauma, loud noises)
- Tinnitus/hearing loss
- Recent URIs
- Focal neuro deficits
- Once vertigo is established, try to differentiate peripheral and central causes. Central causes are often the more acutely concerning because they include mass lesion, stroke, as well as demyelinating conditions, etc
In one study, the presence of vertigo upon waking up in the morning was predictive of a peripheral cause.
Provoking factors may also be helpful in identifying a diagnosis.
- Symptoms provoked by…
- positional changes: BPPV
- recent URI: vestibular neuronitis or labrynthitis
- migraine triggers: vestibular migraine
- straining, recent head trauma, loud noises: perilymphatic fistula
Remember that the Romberg test is generally not a test for cerebellar function but for peripheral neuropathy.
Finally, the HINTS (Head Impuse, Nystagmus, Test of Skew) exam! This test is useful for distinguishing brainstem and cerebellar ischemia from vestibular neuritis or other peripheral causes of vertigo and is most helpful in patients who have had continuous feelings of vertigo or dizziness. It is not useful in patients with momentary position-related transient vertigo (often benign positional vertigo) or those with TIAs who are not dizzy when examined
HINTS was found to have a sensitivity of 96.5% and specificity of 84.4% in identifying central causes of vertigo, which was much better than ABCD2. This is even better than MRI
To summarize: a REASSURING HINTS exam is ALL of the following 1) unidirectional nystagmus 2) no vertical skew 3) abnormal head impulse test (abnormal = nerve problem, not brain problem).
Neuromyelitis optica (NMO)
NMO is a demyelinating disease that primarily targets the optic nerves and spinal cord. 55-85% of brain imaging is normal, although patients can have nonspecific optic nerve enhancement and C/T spine enhancement. Almost all lesions are spinal cord or in cranial nerves.
- bilateral or rapidly sequential optic neuritis
- transverse myelitis (leading to limb weakness, sensory loss, bladder dysfunction)
- Trunk/leg pain
- NMO was originally classified as part of MS
- NMO is now recognized as a separate disease because they do worse than MS patients. NMO is also associated with IgG antibodies to Aquaporin 4, although this is neither necessary nor sufficient for diagnosis
- NMO shares many features with MS, such as the development of lesions over time and space
- More acute than MS; progressive decline over several years w/ a higher mortality than MS
- NMO lesions are almost exclusively brain stem and cranial nerves, and may include transverse myelitis
Differentiating NMO from MS is based on differences with respect to clinical course, pathophys, and response to MS drugs. Some radiographic features that are more suggestive of MS than NMO:
• Lesions adjacent to lateral ventricle
• Inferior temporal lobe white matter lesions
• Ovoid (ie, “Dawson finger”) periventricular lesions
• U-fiber juxtacortical lesions
Labuguen R. Initial Evaluation of Vertigo. AAFP 2006.