Cervicogenic dizziness: losing your equilibrium!

Following on from his article on cervicogenic headaches, Patrick Gilliam explores the causes of cervicogenic-related dizziness in athletes, how to diagnose and effective treatment options.



Dizziness is a very common complaint in clinical practice, affecting approximately 20-30% of the general population^{Pain Phys. 2015. 18: 583-595}. It can manifest as faintness, unsteadiness, a perception of spinning, and disorientation^{Chiro & Man Th. 2011. 19-21}. The mechanisms causing these symptoms are multiple, and can involve several different organ systems. In particular, dizziness can be experienced from disturbances of the ear, nose and throat; cardiovascular system; and central nervous system (CNS)^{Pain Phys. 2015. 18: 583-595 Man Th. 2005. 10: 4-13}.

More commonly in sport however, is the association of dizziness in 20-58% of athletes who sustain a traumatic cervical flexion-extension injury or ‘whiplash’ injury^{Pain Phys. 2015. 18: 583-595 Chiro & Man Th. 2011. 19-21 JOSPT 2000. 30(12): 755-766}. This can occur due to dysfunction in the upper cervical spine and sensorimotor control disturbances^{Pain Phys. 2015. 18: 583-595 Man Th. 2008. 13: 2-11}. This specific type of dizziness is referred to as cervicogenic dizziness (CGD)^{Chiro & Man Th. 2011. 19-21}.

Table 1: Duration and frequency of common causes of dizziness
Cause	Common symptoms	Frequency	Duration	Related Factors
Benign paroxysmal positional vertigo	Vertigo	Episodic	Seconds	Head position, usually worse in the morning
Cervicogenic Dizziness	Dizziness, disequilibrium	Episodic	Minutes to hours	Related to head position
Perilymphatic fistula	Disequilibrium, vertigo	Episodic	Seconds to minutes	Vertigo during Valsalva manoeuver
Labyrinthine concussion	Vertigo, disequilibrium	Episodic	Hours to days	Increases with fatigue
Central vestibular dysfunction	Dizziness, disequilibrium	More constant	Days to weeks	Combined with inner ear pathologies

Presentation

Table 1 gives an idea of how to distinguish dizziness with cervicogenic origin from that of other causes. In addition, common distinguishing features of CGD include associated neck pain, restricted cervicothoracic range of motion, and headaches^{JOSPT 2000. 30(12): 755-766 Dis & Rehab. 2007. 29(15): 1193-1205}. Furthermore, hypertonicity to dorsal soft tissue (particularly suboccipital musculature) and positive pain provocation with palpation to cervical zygapophyseal joints are likely^{Dis & Rehab. 2007. 29(15): 1193-1205}. Further disturbances with cervical joint positional sense, postural stability, and oculomotor control, such as altered smooth pursuit and saccadic eye movements, can also present with this disorder^{Man Th. 2008. 13: 2-11}.

The proposed mechanism for the above-mentioned characteristics are a result of changes to excitation levels of cervical somatosensory receptors. This is caused by neck pain or trauma, and leads to a sensory mismatch between vestibular and cervical input^{Chiro & Man Th. 2011. 19-21 Man Th. 2008. 1-11}. Literature supports the presence of a strong connection between cervical dorsal roots and the vestibular nuclei (see Figure 2) particularly at levels C2 and C3^{Man Th. 2005. 10: 4-13 JOSPT 2000. 30(12): 755-766}.

The cervical afferents are also involved in three reflexes influencing head, eye, and postural stability/proprioception: the cervico-collic reflex, the cervico-ocular reflex, and the tonic neck reflex^{Man Th. 2008. 13: 2-11}. In addition, there is an abundance of mechanoreceptors in the ‘y-muscle’ spindles of the deep segmental upper cervical muscles, which if sensitised by trauma, leads to alterations of proprioceptive signalling to the CNS (see figure 1)^{Pain Phys. 2015. 18: 583-595 Arch Phys Med Rehabil. 1996. 77: 874-882}. With this in mind, it is understandable that injury or trauma of the neck may be associated with a sense of dizziness or disequilibrium.

Figure 1: Link between cervical afferents and the vestibular nuclei/oculomotor afferents

Diagnosis

As a result of the previously mentioned competing pathologies, it can be difficult to diagnose the primary cause of dizziness. Obtaining a thorough history from a patient presenting with dizziness is therefore critical to making a decision regarding appropriate care^{Chiro & Man Th. 2011. 19-21 JOSPT 2000. 30(12): 755-766 Man Th. 2008. 13: 2-11 Arch Phys Med Rehabil. 1996. 77: 874-882}. To entertain a diagnosis of CGD, the therapist must be able to correlate the onset and diagnosis of the dizziness symptoms with the neck pain o r dysfunction ( i e with cervical movements^{JOSPT 2000. 30(12): 755-766}. Commonly, the most provocative cervical movement is extension; however, CGD can be reproduced with rotation or (more rarely) flexion^{Man Th. 2008. 1-11}.

Table 2: Co-existing symptoms with dizziness, which indicate additional pathology
Unexplained symptoms suggestive of CNS pathology (require immediate medical attention)	Symptoms suggestive of vestibular pathology	Symptoms appropriate for physiotherapy input
-Constant vertigo -Feeling of being pushed to one side -Facial asymmetry -Swallowing dysfunction -Speech problems -Oculomotor dysfunction (cranial nerves Ill, IV, VI) -Ptosis -Vertical nystagmus -Loss of consciousness -Repeated, unexplained falls -Changes in sensation -Severe headache -Upper motor neuron signs and symptom	-Constant dizziness -Unilateral hearing loss -New onset of tinnitus -Aural fullness (stuffiness in ear) -Ear pain -Transient vertigo	-Transient dizziness -Cervical pain -Limited cervical range of motion -Radicular upper extremity symptoms -Headache -Balance complaints -Jaw pain -Visual sensitivity

Table 2 lists co-existing symptoms that should be explored further because they are suggestive of CNS or inner ear (vestibular) pathology. Such symptoms would require further investigation and would not be appropriate for physiotherapy treatment^{JOSPT 2000. 30(12): 755-766}.

Another pathology which can cause dizziness and unsteadiness, and which should not be misdiagnosed is damage to the vertebral artery or vertebrobasilar arterial injury. This can be present following head and neck trauma^{JOSPT 2000. 30(12): 755-766 Man Th. 2008. 13: 2-11}. If there is any suspicion of vascular involvement, a clinical framework has been proposed providing an accurate guideline for assessment and management^{Manual Th. 2014. 19: 222-228}. Likewise, it is worth noting that dizziness can be caused by elevated anxiety and medication intake as well^{Man Th. 2008. 13: 2-11}.

To quantify the functional impact of CGD, the Dizziness Handicap Inventory Questionnaire has been proposed (www.rehab.msu.edu/_files/_docs/ Dizziness_Handicap_Inventory.pdf). The purpose of this scale is to identify diff icul ties that someone may be experiencing because of dizziness. Although this assessment is not specific to athletes, it can be helpful as a valid and reliable outcome measure^{Man Th. 2008. 13: 2-11 Man Th. 2008. 1-11 Phys Th. 2014. 94(4): 466-476}.

Other measurable outcomes for symptoms can include a 5-point scale for intensity of dizziness (0=no, 1=mild, 2=moderate, 3=severe, and 4=very severe^{Dis & Rehab. 2007. 29(15): 1193-1205}. Similarly, frequency of dizziness can be measured on a 6-point scale (0=no dizziness, 1=dizziness less than once per month, 2=1-4 episodes of dizziness per month, 3=1-4 episodes per week, 4=once daily, and 5=more than once per day or constant)^{Man Th. 2008. 1-11}.

Assessment

Pain provocation and disruptions to cervico-thoracic range of movement can be assessed using a neuromusculoskeletal objective assessment, while the effect on CGD symptoms is monitored. To gauge any additional sensorimotor control disturbances however, clinical assessment of cervical joint position sense (Figure 2), oculomotor control, and postural instability or balance/ proprioception can be very useful^{Pain Phys. 2015. 18: 583-595 Chiro & Man Th. 2011. 19-21 JOSPT 2000. 30(12): 755-766 Man Th. 2008. 13: 2-11}.

Figure 2: Cervical joint positioning sense assessment

Figure 3: Postural stability assessment

Oculomotor control assessment

This includes gaze stability (the ability to maintain gaze of a target while the head is moving), smooth pursuit (eyes follow a target whilst keeping the head still), saccadic eye movements (eyes fixed on a target that is moved quickly), and eye/head coordination (maintaining gaze when both the head and eyes are moving in between two targets – leading with the eyes first). Symptom provocation is a positive test, as well as, noting any abnormal coordination of the task^{Man Th. 2008. 13: 2-11}. Similarly, these tests can be used for rehabilitation, and with appropriate adaptation, can be made more functional to sporting tasks.

Figure 4: Unilateral C1 rotation sustained natural apophyseal glide (SNAG)

Figure 5: Central C2 SNAG

Treatment

Researchers have argued that once a confident diagnosis has been achieved, management of CGD should be the same as for cervical pain, supporting the role of manual therapy for long-term benefits^{Pain Phys. 2015. 18: 583-595 Chiro & Man Th. 2011. 19-21 Man Th. 2005. 10: 4-13 JOSPT 2000. 30(12): 755-766 Dis & Rehab. 2007. 29(15): 1193-1205 Man Th. 2008. 1-11 Arch Phys Med Rehabil. 1996. 77: 874-882 Phys Th. 2014. 94(4): 466-476}. Following trauma, it is thought that type 1 cervical articular mechanoreceptor and proprioceptors from dysfunctional joints results in a loss of normal afferent input. This leads to aberrant information being sent to the vestibular nuclei, thus formulating symptoms similar to vestibular disturbances, such as dizziness^{Man Th. 2005. 10: 4-13}.

With this in mind, cervical spine mobilisation techniques (sustained natural apophyseal glides, and Maitland mobilisations) have been shown to be effective in restoring normal movement of the zygapophyseal joints. The benefits include a reduction in pain and muscle hypertonicity, which helps re-establish normal proprioceptive and biomechanical functioning to the cervical spine^{Pain Phys. 2015. 18: 583-595 Man Th. 2005. 10: 4-13 Phys Th. 2014. 94(4): 466-476}.

If these techniques described above are successful then a self-SNAG (as described in issue 159) can be recommended for the patient to try at home using a towel or belt/ strap. In general, it has been proposed that these techniques should be utilised over a course of four to six sessions, which should produce a long-term reduction in symptoms^{Man Th. 2005. 10: 4-13 Man Th. 2008. 1-11 Phys Th. 2014. 94(4): 466-476}. Combining these manual techniques with sensorimotor control rehabilitation, as described previously, is recommended by the majority of literature^{Pain Phys. 2015. 18: 583-595 Man Th. 2008. 13: 2-11 Dis & Rehab. 2007. 29(15): 1193-1205 Arch Phys Med Rehabil. 1996. 77: 874-882};however, remains inconclusive in a minority of research^{Chiro & Man Th. 2011. 19-21}.

Summary

CGD is a diagnosis characterised by dizziness and disequilibrium, which is associated with neck pain, most commonly following neck trauma, such as forced cervical flexion-extension mechanisms in sport. The diagnosis relies on the basis of history and examination, and should prioritise the exclusion of other possible causes of dizziness, including involvement of the CNS, cardiovascular, and vestibular systems. Physiotherapy intervention is not appropriate if there is any suspicion of these systems being the source of symptoms. In this instance, onward referral to a clinical specialist should take precedence.

When diagnosed correctly, there is good support for the use of manual therapy techniques to produce a long-term reduction in symptoms. Given the prevalence of sensorimotor control disturbances associated with dysfunction to the upper cervical spine, the addition of sports-specific rehabilitation focusing on regaining this control can be clinically justified.