Sensorimotor Impairment in Neck Pain

Original Editor - Tarina van der Stockt

Top Contributors - Tarina van der Stockt and Wendy Walker


Sensorimotor Function

The cervical spine has numerous mechanoreceptors responsible for proprioceptive input. These receptors have central and reflex connection to the vestibular and visual systems and the central nervous system. [1] Mechanoreceptor input from the upper cervical region and muscles leads to a coordination between vision and movement of the neck. [2]

A very high amount of muscle spindles are found in the suboccipital area. The muscles in this area, in particular the suboccipital muscles are responsible for receiving and sending information to and from the central nervous system. [1]

3 Reflexes also influence sensorimotor control: [2]

  • Cervicocollic reflex [2]
    • works with the vestibulocollic reflex
    • leads to neck muscle activation
    • prevents excessive neck rotation
  • Cervico-ocular reflex [2]
    • works with the vestibulo-ocular and optokinetic reflexes
    • control the extraocular muscles
    • responsible for clear vision when moving the head
  • Tonic neck reflex [2]
    • integrated with the vestibulospinal reflex
    • help keep a stable position of the head when the body is moving by changing muscle activity in the limbs

Sensorimotor Impairment

The cervical receptors can become dysfunctional for e.g. with trauma to the neck, like with a whiplash injury. [1] Receptor sensitivity is affected by chemical changes, for instance with inflammation. [2] Pain (CNS) and psychosocial stress (SNS) can alter muscle spindle sensitivity. [2] Impairments and changes within the neck muscles (e.g. atrophy, degeneration, fatty infiltration, fatigue) affects the cervical afferent input by changing proprioception, joint mechanics and sensitivity of the muscle spindles. [2]

When the cervical receptors are dysfunctional the following occur: [1] [2]

  • Afferent input from these receptors get altered
  • The receptors become functionally impaired
  • Muscle spindle sensitivity change
  • ”Vast effects of pain at many levels of the nervous system”
  • This changes the “integration, timing, and tuning of sensorimotor control” [1]

More sensorimotor dysfunction occur with injury to the upper cervical region than the lower cervical region because the upper region contains more muscle spindles, has a greater connection to the visual and vestibular systems, and more reflex activity. [2] [3]

Postural stability changes happen because of changes in the sensory input between the upper cervical spine and the vestibular structures. Thus the patient’s vestibular structures are unable to distinguish between the inaccurate information resulting in a sensory mismatch that leads to feelings of dizziness/unsteadiness. [2] Patients with neck pain may have an increase in muscle activity/stiffness as the body tries to compensate for a loss of balance. [2]

With chronic whiplash associated disorder (WAD) patients report feelings of dizziness and unsteadiness even though they do not have any vestibular problems. [4]

3 pillars of sensorimotor impairment:

Research did not find any association between these 3 pillars and medication use, age, anxiety, or compensation status. [4]

Symptoms of Sensorimotor Impairment

Changes in sensorimotor control in patients with neck pain, can lead to the following symptoms:[1]

  • Altered sense of cervical joint position (proprioception)
  • Changes in eye movement control
  • Changes in postural stability
  • Subtle dizziness
  • Subtle unsteadiness
  • Lightheaded [2]
  • Feeling of spinning in the head (not the surroundings spinning like with vertigo) [2]
  • Poor head-neck posture awareness (Some patients feel that their head “wobbles”) [2]
  • Visual disturbances (blurry vision, a smaller visual field, seeing grey spots, temporary blindness, photophobia, and vision impairments) - some patients with neck pain have difficulty reading.

Subjective symptoms are more prominent early in the day when the patient’s neck is stiff, and later during the day when the muscles are fatigued. [2] Symptoms may also be provoked with quick head movements, watching a moving object, or when walking when it is dark. [2]

Tests

Proprioception

  • Also called cervical joint position error (JPE) [4]
  • Considered a primary measure of mismatched cervical afferent input leading to abnormalities with sensorimotor control [4]
  • Positive in whiplash patients [4]
  • Test [2]
    • laser point fixed to a headband
    • sitting 90 -100 cm away from a wall
    • patient’s head in neutral, patient closes eyes and then rotates the head and then return to neutral
    • measure the average difference between the start and end position after 3 tries to each side
    • a difference of more than 6.5 cm shows a dysfunction (positive test) - normal is approximately 3-5 cm.
    • patients may have jerky movements, “search” for the right position, or overshoot (sign of altered cervicocollic reflex)
    • some patients may complain of feelings of dizziness or unsteadiness during the test


Eye movement Control

Smooth Pursuit Test

  • Tests eye movement control with the head and trunk in neutral and then compare it to the next test when the trunk is rotated [2]
  • Test
    • Patient in a sitting position. An object is moved slowly from side to side in front of the patient and the patient should follow only with the eyes.
  • Symptoms [2]
    • Quick saccadic eye movements - it looks like the eye is trying to catch up with the object, especially in mid-range
    • Reproduction of patient’s symptoms like dizziness or blurry vision

Smooth Pursuit Neck Torsion (SPNT) Test

  • Will detect eye movement changes due to changes in the cervical afferent input [2]
  • Neck-influenced eye movement control 8
  • Test
    • The head remains in neutral while the trunk is rotated 45 degrees [4] in either direction [2]
    • repeat the previous test
  • Positive:
    • change in eye movement control when the trunk is rotated [4], an increase in saccadic eye movements [2]
    • usually seen in patients with neck pain due to whiplash [2]
  • If the patient has poor performance with the first test and the performance remains the same with the second test then it is most likely a CNS disorder and not sensorimotor impairment [2]

Gaze stability [2]

  • Moving the head while focusing on an object.
  • Patient in a sitting position
  • Looking at a point straight forward
  • Keep looking at this point while moving the head left and right, or into flexion and extension
  • Patients with neck pain struggle to perform the test accurately, they are unable to keep their eyes fixed on the point or has less speed and range (<45 degrees) than individuals without neck pain.


Balance and postural stability

Usually patients don’t realise their balance is affected until it is tested [2]

Tests [4] [2]

  • Bilateral stance
    • comfortable and narrow standing with eyes open and closed, for 30 seconds
    • first on a firm surface and then a soft surface (10-cm foam)
  • Tandem and single limb stance
    • firm surface
    • eyes open and closed and hold for 30 seconds
    • tandem normally impaired in people 45 years of age and older
    • eyes open and closed and hold for 30 seconds
  • Positive [2] [4]
    • large sway in comfortable stance
    • antero-posterior sway in narrow stance
    • difficulty correcting or preventing sway (signs of rigidity)
    • maintaining stance for <30sec
  • Changes in the cervical afferent input might be responsible for the sway people have in comfortable stance after a whiplash injury [4]


Differentiation

  • Peripheral vestibular damage [4] (include benign paroxysmal positional vertigo, damage to the endolymphatic sac, or a perilymph fistula)[10]
    • 35% of patients who have traumatic neck pain due to a high force incident may have vestibular damage[10]
    • SPNT test differentiates between vestibular pathology and cervical afferent dysfunction due to neck pain
    • There needs to be coordination between the cervical and vestibular input so that the brain stem can determine where the position of the head is in space
    • postural stability: more disturbances in the more challenging positions like narrow standing on a soft surface with the eyes closed
    • pronounced vertigo
  • Acoustic neuroma (vestibular involvement) [4]
    • negative SPNT test
    • more disturbances in postural stability when standing on a soft surface with a narrow base of support with eyes closed but more stable in comfortable stance positions than someone with neck pain and sensorimotor impairment
    • Symptoms of tinnitus, blurry vision, confusion and loss of hearing are exacerbated when the patient walks in a crowded place, make sudden movements, or when feeling stressed.
  • Vertebrobasilar insufficiency / Cervical arterial dysfunction
    • Rule out VBI
    • Patients may complain of double vision (double vision is not that evident with somatosensory disturbances) [2]
    • Vertebral artery dissection is rare but should always be considered when assessing a patient with sensorimotor changes and particularly if they complain of severe neck pain and headache on one side and have "transient or ongoing specific neurological dysfunction".[10]
  • CNS disorder
    • Symptoms remain unchanged when doing the SPNT test
    • Should be considered with a direct blow to the head [10]
  • Benign Paroxysmal Positional Vertigo
    • Symptoms are episodic, when changing head position like moving in bed or bending over
    • Vertigo and dizziness lasting 1 minute or less
  • Anxiety, medication, stress

Any central nervous system signs, or symptoms without a diagnosis/reason is a red flag and the patient should be referred to a medical doctor. [2]


For more information see page 6 of this journal article to read about specific tests for differentiation.

General Management[2]

In patients with minimal sensorimotor proprioception impairment conventional management might be sufficient. [4]

  • Manipulative therapy - improves dizziness and cervical proprioception
  • Training focusing on neuromuscular control - improves cervical proprioception
  • Training focusing on cervical muscle endurance - improves balance
  • Acupuncture - improves balance, and cervical proprioception
  • Gaze stability, proprioception and eye-neck coordination training - improves sensorimotor deficits as well as ROM and neck pain and disability.
  • Vestibular rehabilitation - can improve balance problems and dizziness in patients with whiplash injury
  • Balance retraining
  • Trigger point therapy
  • ROM and neck proprioception exercises
  • PNF
  • Deep neck flexor strengthening

These treatments alone cannot improve all the sensorimotor dysfunctions.

Patient with a significant sensorimotor proprioception impairment with neck pain would need focused management of the affected areas to help maintain symptoms, avoid relapse and worsening of symptoms. [4]

Combined approaches have been shown to work best for these patients.[2]


Specific sensorimotor control intervention [2]

Develop a specific program with combined approaches for the dysfunction the patient presents with. Work on the aspects that turns on the dizziness by starting slow with small movements and then progressing.

Patient should not experience an increase in pain or headache, if this happens the exercises should be less challenging and in a more supported position, like lying. During the vestibular exercises patients may experience temporary increase of symptoms such as nausea, subtle dizziness/unsteadiness, or visual disturbances.

Exercises should be done 1-2x per day, 3-5 repetitions each and progressing to 10 repetitions. Start in easier stable position and at a speed where the patient can move precision. Increase range and speed as the patient improves and progress to softer surfaces or more difficult positions (like tandem).

General guidelines: [11]

  • "Work on what turns on the dizziness"[11]
  • Start in a seated position, progress to standing, tandem standing and walking
  • Progress exercise duration to 30sec 2x day, then 1-2 min 3x day up to 5 min 5x day
  • Vision should be unrestricted initially and then progress to restricted peripheral vision
  • When practicing eye movement or gaze stability you can start with a dot, then a word, and later on a business card

Proprioception/ Cervical Joint Position Error (JPE) [2]

  • Patient sitting in front of a wall with a laser pointer fixed to a headband (like the assessment)
    • Patient needs to bring the head back to neutral from any direction for e.g. rotation or extension
    • Train the most difficult/symptomatic direction by rotating towards or from the impaired side
    • eyes open and then progress to eyes closed and then open to check position
    • progress to let patient stop at certain intervals for instance at 20 degrees or 40 degrees
    • progress by doing the exercise in different standing positions
    • progress by tracing a figure-of-8 with the laser

Eye movement Control

Smooth Pursuit

  • Practicing smooth pursuit with the eyes while the head is still and then rotate the trunk and repeat the exercise [2]
  • Patient can practice this at home by moving their thumb in front of them and pursuing the movement with their eyes.
  • Start with the body and head in neutral, progress to 30 degrees and 45 degrees torsion [11]


Gaze stability [2]

  • Training should focus on the movement that creates the most symptoms
  • Patient should focus on a spot on the wall in front of them and then the patient moves the head while still focusing the eyes on the spot.
  • Patient can move the trunk or therapist can move the trunk if the patient sits on a stool while the patient keeps the eyes fixed on the object
  • Progress by changing the object the patient focus on, change the background to stripes or checks, increase speed and ROM, restrict peripheral vision, standing instead of sitting


Balance and postural stability [2]

Balance training can lead to an increase of dizziness and muscle stiffness. Both of these are undesirable for a patient with neck pain as it will increase their symptoms leading to further exacerbation. Thus the therapist should monitor the patient and progress slowly to avoid exacerbation of symptoms and muscle stiffness.

  • Balance training should start at the level the patient was at during the assessment and aiming to reach 30 seconds static standing balance
    • Progress by changing the standing position or surface and closing the eyes
  • Functional tasks - walking while changing head position (rotated, looking up or down) while keeping the same speed and direction.
    • Progress by changing the surface and walking speed

Patient can practice these exercises at home, preferably in a corner of the home where they can correct when they lose their balance. [1]

Some research has shown that after neck coordination exercises participants had improved balance. [21]

Resources

References

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