Neurologie FN Motol Cervicogennous Vertigo and significance of the cervical test

Neurologie FN Motol Clinical notes n cervicogenous vertigo is a frequent clinical diagnosis (4-10% of all dizzy cases in various series) n disturbance of cervical motility and cervical pain in association with vertigo are the hallmarks of the diagnosis n objective criteria are missing n X- ray is of little value n typical exclusion diagnosis, cave affection of the brain stem structures and/or vertebro-basilar vessels n response to the appropriate physical treatment reinforces the correct diagnosis n Notwithstanding, it is felt, that because reliable diagnostic tool is missing, this diagnosis is often assumed rather uncritically

Neurologie FN Motol Pathogenesis n The three main theories on the ethiopathogenesis of cervical vertigo are widely believed : n overexcitation of cervical sympathetic nerves n abnormally increased neck (cervico-ocular) reflex due to hyperexcitation of neck proprioceptors n ischemia due to mechanical compression or stenosis of the vertebral artery n All these theories are well supported clinically and experimentally, so multiple mechanisms in the etiology of cervical vertigo must be considered.

Neurologie FN Motol Cervical test n Registration of the ocular movements provoked by passive trunk to stationary held head rotation n based on the cervico-ocular reflex (COR) n may be candidate for non-invasive, quantitave assessment of the neck proprioceptive influx n principle - neck torsion without head in space movement, i.e. without vestibular stimulation n many paradigms used differ in the velocity profiles, frequencies used, may include static torsion or dynamic movements n clinical variant known as De Kleyn test, is designed particularly for diagnosis of vertebral arteries involvement

Neurologie FN Motol Anatomical basis n cervical afferents to the vestibular nuclei are believed to be the substrate of cervical reflexes n spindle fibbers from perivertebral muscles play a major role in the cervical reflexes n proprioceptive endings of the occipitoatloid and atlantoaxial articulations, which are innervated by the C1 and C2 spinal roots also contributes to this pathways n at least two cervico-vestibular pathways were identified : n a direct one in which fibbers arrive through the posterior root of the first cervical segment along the posterior columns n the indirect way is represented by the spinocerebellar dorsal fascicle that courses in the lateral columns of the spinal cord

Neurologie FN Motol Physiology of cervico-ocular reflex - 1 n Barany (1906) first observed neck-induced eye reflex in the rabbit and in new born humans. n these response was trunk-directed and “compensatory” in nature - i.e. neck induced movement was synergistic to the vestibulo-ocular movement provoked by the head rotation in the same sense n head-directed movements are “anticompensatory” - i.e. they act against the VOR which would be evoked by the illusory head rotation n these “anticompensatory” movements are functionally relevant when head and trunk are turning in the same direction with velocities (dancing, sport)

Neurologie FN Motol Physiology of cervico-ocular reflex 2 n contradictory results were obtained by many authors when recording the eye movements evoked by neck torsion n both compensatory,anticompensatory and intermediate movements were documented n the results depend on the stimulus frequency with shift towards compensation with slower rotations and behavioural context (head in the space vs.. trunk in the space concepts) n Jurgens and Mergner (1989) demonstrated definite cervicogennic response in a group of 20 healthy subjects, n enhancement of VOR by combination of neck and vestibular stimuli n shift of the neck induced eye movements towards compensation from 0.2 Hz to 0.05 Hz

Neurologie FN Motol Clinical significance n clinical significance of these physiological phenomenon was questioned in some reports n similar results were drawn from control subjects and from clinical population n No influence on eye movements, verticality perception and postural stability was noted in patients with cervicogenic headache in following unilateral anaesthetic C2-blockades n On the other hand clear connection between clinical and electrophysiological (ENG, nuchal muscles EMG) findings was documented in a follow-up study on more the 200 patients n These contradictory results forced us to conduct study aimed to the development of objective method for assessment of cervical ocular reflex activity in clinical practice.

Neurologie FN Motol Cervical test methodology n Trunk rotates sinusoidaly (60o to both sides, peak velocity 60 o/sec, 0,1 Hz) with head fixed by technician. For the sake of safety no mechanical fixation is used. The movement of the chair starts to the left side (i.e.relative movement of the head to the right) - dynamic phase, and after three cycles stops in the leftmost position for 20 seconds - static phase. n Rotation to the rightmost position with the second static phase for 20 seconds and finally another 3 cycles of the second dynamic phase. The eye movements are recorded by conventional DC electronystagmography from binocular horizontal derivation in darkness with eyes open.

Neurologie FN Motol Control group N = 10 n clear head-directed (i.e. anticompensatory) slow deviations of the eyes in all cases n cervico-ocular responses were typically variable and fluctuating in amplitude. n during the sustained trunk rotation the eyes drifted slowly to the center position n these movements correspond to the slow phases of vestibular nystagmus, no quick phases were triggered n the same rotation was delivered with head free and vestibulo- ocular response with clearly differentiated nystagmus beats was recorded in all subjects

Neurologie FN Motol Control group N = 10, COR gain n Gain (peak eye velocity/peak trunk velocity) of the ocular movements elicited by trunk-to- head rotation in normal subjects :

Neurologie FN Motol Clinical application of cervical test :

Neurologie FN Motol CONCLUSIONS : n regular slow head-directed eye movements are evoked by trunk-to-head rotation in normal individuals n no nystagmus beats are apparent in normals, it means, no nystagmus quick phases are triggered n nystagmus evoked by dynamic or static neck torsion is considered as pathologic phenomenon based both on our experimental results and clinical series n several patterns of cervical test abnormalities were identified

Neurologie FN Motol CONCLUSIONS : n the results of cervical test can be interpreted only in light of the complete neuro-otological investigation. Similar records can be obtained with different pathologic conditions n another techniques that could theoretically reveal the abnormal cervico-vestibular proprioceptive input include EMG registration of the nuchal muscles activity, vibrational and/or electrical perivertebral stimulations and pharmacologic manipulations. The real impact of these methods remains to be evaluated