Migraine Ménière’s syndrome Ménière's disease is idiopathic, but it is believed to be linked to endolymphatic hydrops, an excess of fluid in the inner ear intense vertigo+nausea, hearing disturbance, pressure in repeated attacks Days Vestibular neuritis OR vestibular infarction of labyrinth intense vertigo+nausea + hearing disturbance isolated or repeated attacks Fluctuating / continuous Uncompensated vestibular lesion: mild vertigo + nausea Functional vertigo = psychogenic vertigo [ie without disorder to the system]: mild vertigo + disproportionate disability ‘Silent’ Acoustic neuroma mild imbalance if any, tinnitus, hearing loss also: ototoxic antibiotics demyelinating disease Vestibular nystagmus: In acute unilateral Vestibular disorder the unopposed tonus of the intact canal causes the eyes are driven to the lesioned side; a vestibular-ocular reflex as if the head were turning to the intact side in which case the natural reflex response would be to move eyes in the opposite direction to maintain vision on the object This drifting movement is detected by the brainstem which intermittently resets eye position with fast saccades [Saccades direct the fovea onto an object or region of interest] generating the overall pattern of a nystagmus’ which beats to ‘vestibular the intact side. Such nystagmus is florid only in the acute phase of loss and is minimised by visual suppression mechanisms. nystagmus may sometimes ‘vestibular torsional and very occasionally vertical. Vestibular-ocular reflex Reticular nuclei / formation are important in this function because it involves a saccade (prob between the diversion to cerebellum and the transmission to contralateral abducens A head movement to the right gives stimulation of the canal on the right which signals for excitation of contralateral abducens [via one cross of the midline] nerve and excitation of ipsilateral occulomotor [via two crosses of the midline overall] nerve to give eye movement to the left Inhibitory signalling to the left canal gives complementary relaxation of opposing muscles Superior and medial vestibular neurons project to motor nuclei supplying extraocular muscles
Migraine Ménière’s syndrome Ménière's disease is idiopathic, but it is believed to be linked to endolymphatic hydrops, an excess of fluid in the inner ear intense vertigo+nausea, hearing disturbance, pressure in repeated attacks Days Vestibular neuritis OR vestibular infarction of labyrinth intense vertigo+nausea + hearing disturbance isolated or repeated attacks Fluctuating / continuous Uncompensated vestibular lesion: mild vertigo + nausea Functional vertigo = psychogenic vertigo [ie without disorder to the system]: mild vertigo + disproportionate disability ‘Silent’ Acoustic neuroma mild imbalance if any, tinnitus, hearing loss also: ototoxic antibiotics demyelinating disease Vestibular nystagmus: In acute unilateral Vestibular disorder the unopposed tonus of the intact canal causes the eyes are driven to the lesioned side; a vestibular-ocular reflex as if the head were turning to the intact side in which case the natural reflex response would be to move eyes in the opposite direction to maintain vision on the object This drifting movement is detected by the brainstem which intermittently resets eye position with fast saccades [Saccades direct the fovea onto an object or region of interest] generating the overall pattern of a ‘vestibular nystagmus’ which beats to the intact side. Such nystagmus is florid only in the acute phase of loss and is minimised by visual suppression mechanisms. ‘vestibular nystagmus may sometimes torsional and very occasionally vertical. Vestibular-ocular reflex Reticular nuclei / formation are important in this function because it involves a saccade (prob between the diversion to cerebellum and the transmission to contralateral abducens A head movement to the right gives stimulation of the canal on the right which signals for excitation of contralateral abducens [via one cross of the midline] nerve and excitation of ipsilateral occulomotor [via two crosses of the midline overall] nerve to give eye movement to the left Inhibitory signalling to the left canal gives complementary relaxation of opposing muscles Superior and medial vestibular neurons project to motor nuclei supplying extraocular muscles