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
- 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
- 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.
Peripheral
Central
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
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