Vestibular disease Flashcards
Anatomy of the vestibular system
Peripheral part:
- sensory receptors (in the vestibular apparatus)
- vestibulocochlear nerve CNVIII
Central part:
- Brainstem - vestibular nuclei
- (cerebellum, thalamus, cranial cervical spine)
Function of the vestibular system
Maintain an animals balance and orientation wrt gravity
Including maintaing position of eyes, trunk, and limbs
It also controls eye movements in relation to movements of the head
Clinical signs of unilateral vestibular dysfunction
Imbalance
Abnormal head, limb/body, and eye position
Abnormal eye movements
Head tilt towards the lesion (unless paradoxical)
Ataxia with a wide based stance, circling, leaning, falling, or rolling towards a lesion
Strabismus (often positional), nystagmus
Clinical signs of bilateral vestibular dysfunction
Wide excursions of the head from side to side and a lack of physiological nystagmus
Neurological exam findings in central vestibular disease (brainstem and cerebellum)
Mentation: may be affected
Head tilt: ipsilateral or contralateral
Gait: vestibular ataxia, can present paresis, proprioceptive ataxia, dysmetria
Postural reaction deficits: may be ppresent on the side of the lesion
Nystagmus: pure vertical, horizontal, rotatory. Can change direction with change of head position
Intention tremor: with cerebellar lesion
Neurological exam findings in peripheral vestibular disease (inner ear and CN VIII)
Mentation: normal
Head tilt: ipsilateral
Gait: vestibular ataxia, no paresis
Postural reaction deficits: normal
Nystagmus: VII, sympathetic innervation of the eye (Horner’s)
Intention tremor: no
Types of nystagmus
Horizontal, rotatory, or vertical
Spontaneous or positional
Jerk or pendular
Spontaneous nystagmus
observed when head in normal position
Due to different stimulation of the vestibular system
Postional nystagmus
Elicited by moving the head in an unusual position i.e. either by lifting the head or by lying the animal on its back
Jerk nystagmus
Has a slow and rapid phase
Typically observed in vestibular disorders
Pendular nystagmus
Sinusoidal
Typically observed in cerebellar disorders
Circling
Seen in vestibular and fore brain diseases.
CIrcles are usually narrow in vestibular diseases, compared with wide compulsive circles in forebrain diseases.
Paradoxical vestibular disease
The head tilt is paradoxical
Cerebellar lesion (caudal cerebellar peduncle and flocculonodular lobe)
Sometimes other cerebellar signs
Vascular central vestibular diseases
Infarction, haemorrhage
Infectious/inflammatory central vestibular diseases
Meningoencephalitis (MUO)
Empyaema, Toxoplasma/neospora, FIP
Idiopathic central vestibular diseases
Arachnoid cysts
Traumatic central vestibular diseases
Head trauma
Toxic central vestibular diseases
Metronidazole
Anomalous central vestibular diseases
Congenital malformation
Neoplastic central vestibular diseases
Brain tumours - primary or metastatic
Nutritional central vestibular diseases
Thiamine deficiency
Degenerative central vestibular diseases
Lysosomal storage disorders
Neurodegenerative diseases