Paraneoplastic Neurologic Syndrome and Nystagmus

Today, we discussed the case of an elderly woman with significant malignancy history who presented with acute kidney injury and a constellation of neurologic symptoms/findings including gait instability, dysarthria, vertical nystagmus, asterixis, and visual hallucinations. A diagnostic mystery, but a fascinating case to think about the differential diagnosis, which included paraneoplastic neurologic syndromes!

A Plug for Paraneoplastic Neurologic Syndromes!

See our prior blog post on paraneoplastic neurologic syndromes: https://ucsfmed.wordpress.com/2016/06/17/moffitt-oncology-report-pearls-61716-paraneoplastic-neurologic-syndromes-and-hyperammonemia/

Differentiating Central versus Peripheral Nystagmus

  • Symptoms: Peripheral nystagmus is often associated with severe vertigo and vomiting; symptoms of central nystagmus range widely from none to pronounced vertigo.
  • Time-course:  peripheral nystagmus almost always remits within a few days to weeks (due to central adaptive mechanisms and development of ability to suppress nystagmus with visual fixation)
  • Waveform: Pure downbeat, pure upbeat, or pure torsional nystagmus are almost always central brainstem signs : pure horizontal or mixed forms are typical of peripheral causes of nystagmus

Different Types of Nystagmus

  • Horizontal Nystagmus  (Peripheral or Central)
    • May be peripheral or central
    • Peripheral: usually due to unilateral loss of labyrinthine input from vestibular neuritis or partial neurectomy : BPPV is due to hyperfunction of the semicircular canal (due to canalithiasis)
    • Central: Think various lesions affecting cerebrum or vestibular nuclei : Wernicke encephalopathy
  • Upbeat Nystagmus  (Central)
    • Most commonly affected lesion is the medulla
    • Most frequent causes: cerebellar degeneration and brainstem/cerebellar stroke
    • Unusual causes: viral encephalitis, meningitis, sarcoidosis, Behcet’s syndrome, anti-GAD antibodies.
  • Downbeat Nystagmus (Central)
    • usually due to damage to dorsal medulla or cerebellar flocculus
    • Most frequent causes include Chiari malformation, cerebellar degenerations, MS, vertebrobasilar infarction, medications, alcohol
  • Torsional Nystagmus (Central)
    • Central nystagmus due to dysfunction of vertical semicircular canal inputs from one side; lesions are at lateral junction of pons and medulla that involve the vestibular nuclei
    • Causes: infarction and multiple sclerosis are most common : Tumors and venous angiomata in pons or cerebellum are the next most frequent causes.

Evernote Link: https://www.evernote.com/shard/s338/sh/75470a13-e2af-4f7c-8abe-409e150807b4/483f379248b67f0883354d38e577de70

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