Neurosurgery notes/Paid/Anatomy/Sensory/Vestibular/Vestibular disorders

Vestibular disorders

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May 31, 2026 12:46 AM GMT+0

Labyrinthine Fistula

  • Aka: Perilymphatic Fistula
  • An abnormal communication between the inner and middle ear
  • Mechanism of Disease
    • A rupture of the round window or oval window ligaments separating the inner and middle ear → fistula between inner and middle ear → this allows the inner ear to be influenced by the intracranial pressure directly
    • Erosive loss of the endochondral bone overlying the labyrinth → The loss of the overlying protective bone allows pressure or mass-induced motion of the underlying endosteum, perilymph, and by contiguity, the endolymphatic compartment → vestibular and sometimes auditory symptoms
      • Aural fullness
      • Fluctuating or non-fluctuating hearing loss
      • Tinnitus
      • Dizziness
      • Vertigo
      • Balance disorders
      • Nausea
      • Spatial disorientation

Benign Paroxysmal Positional Vertigo (BPPV)

  • Most common causes of vertigo
  • Aetiology
    • Can result from a head injury
    • Simply occur among those who are older
  • Mechanism of Disease:
    • Calcium carbonate crystals (otoconia) that are normally embedded in gel in the utricle become dislodged → dislodged otoconia migrate into one or more of the three fluid-filled semicircular canals, where they are not supposed to be → The semicircular canals are sensitive to gravity and changes in head position can be a trigger for BPPV
  • Common Symptoms:
    • Dizziness
    • Vertigo
    • A loss of balance
    • Nausea
    • Visual disturbance
    • Nystagmus
    • Light-headedness
    • These symptoms may last for less than a minute

Brainstem nuclei injury and its associated clinical features

Structure
Main ocular motor function
Clinical findings in lesions
Abducens nucleus*
Conjugate horizontal gaze
Ipsilateral conjugate horizontal gaze palsy
PPRF: paramedian pontine reticular formation
Horizontal saccade generation
Selective horizontal saccadic palsy with sparing of vergence and pursuit
MLF: Medial longitudinal fasciculus
Conjugate gaze and VOR (vestibuloocular reflex)
Internuclear ophthalmoplegia (INO); Convergence can be spared; Skew deviation or ocular tilt reaction (OTR); Asymmetric vertical VOR better with upward slow phases; Dissociated vertical-torsional nystagmus
CTT: central tegmental tract
Conveys information from cerebellum to inferior olive
Oculopalatal tremor
Vestibular nucleus (rostral)
VOR
Spontaneous nystagmus; Abnormal head impulse sign; Skew deviation

Vertigo

  • The illusion of movement of self or environment.
  • Common denominator of symptoms caused by vestibular system dysfunction
  • True vertigo is a far less common complaint as compared with dizziness, a term that encompasses a wide array of meanings.
    • The initial task in the diagnostic approach to dizziness thus consists of querying patients about what they means by “dizziness.”
      • Differential diagnosis to vertigo
        • Ortho-static hypotension
        • Visual impairment, or
        • Proprioceptive loss
  • Anatomic localisation of the lesion
    • Systemic disease that secondarily affect the vestibular system
      • Cardiovascular
      • Endocrine
      • Metabolic diseases
    Peripheral
    • Pathology affects the
      • Vestibular labyrinth
        • Associated symptoms
          • Hearing loss
          • Tinnitus
          • Ear pressure
          • Pain
          • Nystagmus
            • Spontaneous nystagmus, with the quick component directed away from the affected side.
            • Rotary due to involvement of ducts in both the vertical and the horizontal planes, is inhibited by fixation.
            • Associated autonomic symptoms:
              • Sweating,
              • Pallor,
              • Nausea,
              • Vomiting
        • Caused by
          • Lesions in the vestibular labyrinth include viral and bacterial infections
          • Drug toxicity (Aminoglycosides are notoriously ototoxic.)
      • Vestibular ganglia and nerve
        • Associated symptoms (due to close proximity to CN7)
          • Facial weakness
          • Hearing loss
          • Tinnitus
          • Past-pointing to the affected side
          • Lack of
            • Vertigo is less prominent
            • Ear pressure absent
            • Pain absent
    Central
    • Associated clinical features
      • Hearing loss and tinnitus
      • Loss of corneal reflex (ipsilateral) and facial numbness
      • Facial weakness hyperreflexia
      • Hearing loss and tinnitus absent
    • Location
      • Cerebellopontine angle (CPA)
        • Causes
          • Vestibular schwannoma
        • Presentation
          • CN8 compression
            • Progressive hearing loss and tinnitus
          • CN5 compression
            • Loss of the ipsilateral corneal reflex and facial numbness
          • CN7 compression
            • Facial weakness
          • Cerebellum compression
            • Ipsilateral limb ataxia and intention tremor signal
          • Brainstem compression
            • Long-tract signs
              • Contralateral hemiparesis
              • Contralateral hemisensory loss
          • Mild peripheral lesions, vertigo, nystagmus, and autonomic symptoms
            • When compared to peripheral lesion
      • Brainstem and cerebellum.
        • Presentation
          • Diplopia (III, IV, VI),
          • Dysarthria (IX and X), and
          • Perioral numbness (V),
          • Long-tract signs such as hemiparesis (corticospinal tract) and hemisensory loss (spinothalamic tract).
          • Absent hearing loss and tinnitus
          • Mild autonomic symptoms
        • Causes
          • Vertebrobasilar insufficiency,
            • A diminished flow of blood in the vertebrobasilar arterial system
          • Cerebellar lesions
            • PICA Infarction: commonly results in limb ataxia and vertigo.

Dizziness

  • Disequilibrium: Malfunction in one of three separate but communicating systems:
    • Visual system
    • Proprioceptive system
    • Vestibular system
  • True vertigo is a far less common complaint as compared with dizziness, a term that encompasses a wide array of meanings.
    • The initial task in the diagnostic approach to dizziness thus consists of querying patients about what they means by “dizziness.”
      • Differential diagnosis to vertigo
        • Ortho-static hypotension
        • Visual impairment, or
        • Proprioceptive loss

Nystagmus