Postural and Symptomatic Improvement After Physiotherapy in Patients With Dizziness of Suspected Cervical Origin
Patients with dizziness of suspected cervical origin are characterized by impaired postural performance. Physiotherapy reduces neck pain and dizziness and improves postural performance. Neck disorders should be considered when assessing patients complaining of dizziness, but alternative diagnoses are common.
Vertigo and dizziness are common complaints accompanying neck pain. The combination of neck disorders with vertigo or dizziness was termed “cervical vertigo” by Ryan and Cope, a designation that may be misleading as most patients suspected of suffering from it report dizziness or dysequilibrium. Owing to its poor definition and the lack of reliable clinical tests, the entity has been the subject of much debate.
There is evidence of a substantial contribution of cervical proprioceptive input to ocular motor control and postural control in both animals and humans, and vestibular and neck proprioceptive information interact linearly in subjective body orientation and mental representation of space. Consequently, disturbed cervical proprioceptive input has been suggested as a probable cause of cervical vertigo, s Information on the orientation of the head in relation to the trunk is necessary for the execution of appropriate postural responses based on vestibulospinal neural output.
The vestibular receptors cannot provide this information, but it has been suggested that it is provided by the cervical proprioceptors. Furthermore, infiltration of local anesthetics into the deep tissues of the neck causes ataxia and nystagmus in animals, but ataxia without nystagmus in humans. Thus, it is reasonable to assume that disturbed cervical proprioception primarily affects postural control in humans, and patients with neck pain and concomitant dizziness have been reported to manifest impaired postural performance, as compared to healthy subjects.
Postural performance can be assessed objectively by posturography, recording the forces actuated by the subject’s feet on the supporting surface. To enhance the sensitivity of posturography in assessing balance disorders, recordings should preferably be made during or after a postural perturbation, This can be accomplished in various ways: by moving the support surface; by the application of erroneous sensory input, eg, by exposing the proprioceptive receptors to a vibratory stimulus; by exposing the vestibular nerves to a galvanic stimulus; or by exposing the subject to visual disturbance in the form of moving surroundings.
Physiotherapy, traction of the neck, injection of local anesthetics at tender points, or immobilization of the neck with a collar have been suggested as treatments for vertigo or dizziness of cervical origin. Among others, deJong and Bles described recovery of postural stability after treatment directed at the neck in occasional patients with dizziness of suspected cervical origin, but to our knowledge there have been no prospective, controlled studies.
In this study, consecutive patients were examined who had recent onset of neck pain and simultaneous complaints of dizziness or vertigo. Extracervical causes of their complaints were excluded when possible, and no medico-legal issues were known to be involved. The aim was to ascertain whether, as compared with healthy subjects, the selected patients have disturbed postural control as objectively analyzed by posturography, and to investigate in a randomized, controlled setting the effects of physiotherapy on postural performance and subjective symptoms of neck pain and dizziness/vertigo.
The performance of patients with dizziness of suspected cervical origin was significantly poorer than that of the healthy controls in the objective tests of postural performance. This indicates that postural control is impaired in these patients and suggests that cervical disorders may affect human balance function. Physiotherapy, aimed to decrease cervical discomfort, objectively improved the disturbed postural performance and reduced subjective symptoms of dizziness and neck pain. Despite the restricted number of patients, the differences between the Treatment group and the Delayed Treatment group, as well as findings within the Delayed Treatment group, suggest that the improvement was a result of the physiotherapy and not merely an effect of general care or reassuring information as to the cause of the symptoms.
Of the 65 patients considered for inclusion in the study, a majority were excluded because extracervical causes were suspected, eg, owing to histories of head or neck trauma with the possibility of traumatic otolith damage or damage to the brainstem, or neck problems secondary to a vestibular lesion. Thus, the mere combination of neck pain and dizziness should not be called cervical dizziness. These findings are in accord with Brandt’s suggestion that well-established signs and tests can yield a convincing alternative diagnosis in many of these patients? It also stresses the necessity of careful history taking and clinical examination, as well as of electronystagmography, before suspecting cervical dizziness. The patients’ subjective complaints of dizziness were classified according to type, and 10 of the patients reported dysequilibrium alone or in combination with vertigo. This is in accord with Brandt’s suggestion that cervical vertigo manifests itself as a feeling of unsteadiness.
The neck muscles were tender on palpation in all included patients, and 13 of the 17 patients also complained of headaches that were of the tension headache type. These cases may belong to a subcategory of the tension headache or tension neck syndrome, and dizziness is reported to be common in these conditions. None of the patients had had extended periods of sick leave, none was retired or opted for early retirement because of neck problems or vertigo, and none stood to gain medicolegal benefit from the outcome of the testing. Thus, malingering is an unlikely cause of the differences between patients and controls in this study, though it cannot be excluded as a possible source of error. If a patient tries to perform poorly in the postnrographic tests, this usually gives rise to a pattern of high-frequency body sway unaffected by the vibratory stimulus. None of the patients manifested such a pattern.
Vibratory stimulus of muscles produces changes in the signalling of the muscle spindles, interpreted by the CNS as indicating a lengthening of the vibrated muscle. This may induce limb, as well as shifts in body posture (vibration-induced body sway). Vibratory stimulus can thus be used as a tool to perturb human stance in a reproducible manner, and has been used in posturographic testing to reveal the effects on postural performance of different factors such as age, drugs, and vestibular or CNS disorders. Repeated posturographic testing may introduce a source of error due to learning effects. However, both Ishizaki and associates and Uimonen and colleagues reported that vibratory-induced body sway in healthy subjects yielded excellent reproducibility without significant learning effects in repeated posturographic testing, both in shortand long-term use.
Posturography has also been used to objectivize positive effects of habituation and balance retraining physical therapy on postural performance in patients with different vestibular disorders but has hitherto only been used in isolated cases to determine the effects of different treatments on dizziness/vertigo of suspected cervical origin. The physical therapy in the present study was aimed at reducing cervical discomfort and did not include vestibular rehabilitation exercises. Thus, the positive findings cannot be attributed solely to habituation of vestibular or postural reflexes. Because there is no gold standard treatment of cervical dizziness, the choice of physiotherapeutic methods was pragmatic and individualized according to signs and findings, and was aimed at reducing cervical discomfort and pain. Thus, the results do not permit meaningful discussion of the choice of physiotherapeutic regimens.
Carlsson and Rosenhal described oculomotor disturbances in patients with tension headache, as compared with healthy subjects, and reported that treatment with physiotherapy or acupuncture, reducing headaches and neck pain, also improved the disturbed oculomotor function. They also found a significant correlation between the degree of tenderness in the trapezius muscle and the severity of oculomotor disturbances. These authors suggested that the improvement in oculomotor function was a consequence of the reduction of neck muscle tension, secondary to reduction of neck muscle pain. Revel and coworkers reported that patients with chronic cervical pain of unspecified origin, as compared to healthy subjects, had poorer ability to reassume the original position of the head after a voluntary active maximal rotation of the head. This was taken as an indication of altered cervicocephalic kinesthesia and neck proprioception in these patients. In a later study, Revel and colleagues also found that a rehabilitation program, based on eye-neck coordination exercises and aimed to improve neck proprioception, significantly improved cervicocephalic kinesthesia and horizontal rotational active range of neck motion, and significantly reduced neck pain in patients with chronic cervical pain syndromes. Similar findings have been reported by Persson and coworkers in patients with cervical root compression due to disc hernias or spondylosis but without medullary compression. After surgical treatment of the root compression, patients manifested significantly improved postural performance and significantly reduced cervical pain. These reports, together with the findings of the present study, suggest that neck disorders per se can in fact cause dizziness.
Women comprised 80% of the referrals and 88% of the final study population. This female preponderance is consistent with that commonly found in different disorders of the neck, such as tension neck syndrome, cervicogenic headache, and tension headache. A similar preponderance of women was found among subjects with vertiginous complaints in a normal population, where approximately 25% to 30% of women complained of vertigo, as compared with only about 5% of men of comparable age. Similarly, the incidence of motion sickness is higher in women. As motion sickness is considered to be caused by mismatch between conflicting vestibular, visual, and proprioceptive stimuli, the skewed sex distribution might reflect greater susceptibility in women also to sensory mismatch involving cervical proprioception.
In the present study the improvement in postural performance was obvious in the posturographic tests in which vibratory stimulus was applied to the calf muscles, but not in the tests in which it was applied to the neck muscles. The patients were improved with regard to neck pain after physiotherapy, but none was completely free from pain. Thus, the muscle spindles of the neck muscles may still be sensitized. As vihration-induced body sway is believed to be induced via stimulation of the muscle spindles, the patients may still have enhanced sensitivity to vibratory stimulation of the neck. Furthermore, Abrahams and Falchetto have reported that electrical stimulation of nerves from the biventer cervicis muscle in cats facilitated the monosynaptic reflexes in the hindlimbs over supratentorial pathways. Hypothetically, the physiotherapy might have resulted in a reduction of sensitivity of the cervical proprioceptors great enough to normalize the gain of the postural reflexes of the lower extremities, thus normalizing the responses to calf muscle vibration, but not sufficiently reduced to normalize the responses to neck muscle vibration.
In the present study, comparison of the patients after physiotherapy to the group of healthy subjects showed the patients’ posmral performance still to be poorer but not in all tests, and the differences between the groups had diminished. Thus physiotherapy improved but did not normalize the patients’ postural performance. Before physiotherapy the patients manifested significantly greater velocity of body sway than did healthy subjects in three of the four stimulus-free periods of quiet stance. After physiotherapy there were no significant differences between the patients and the healthy subjects in any of the stimulus-free periods. Similarily there were no significant differences in any of the four stimulus-free periods between pretreatment and posttreatment values for the patients. These findings emphasize the importance of using perturbation stimuli in posturography to reduce stochastic variations of unperturbed stance if differences between normal subjects and patients with various lesions are to be found.