Cervical Lecture 4: Clinical Instability, Cervicogenic Dizziness, and Peri-Operative Considerations

Overview of Clinical Instability in the Cervical Spine

  • Neck Pain with Movement Coordination Impairments: This is the International Classification of Functioning, Disability and Health (ICF) category within the Clinical Practice Guidelines (CPG) that encompasses cervical "instability."

  • Conceptualizing Clinical Instability: Stability is achieved through the integration of three subsystems:

    • Passive Subsystem: Bones, ligaments, and joint capsules.

    • Active Subsystem: Muscles.

    • Neural Subsystem: Control mechanisms and feedback loops.

  • Mechanical vs. Clinical Instability:

    • Mechanical Instability: Refers specifically to the instability or failure of the passive subsystem components.

    • Clinical Instability: Characterized by a lack of neuromuscular control or muscular function required to control movement between the extremes of stability provided by the passive subsystem. It is defined as "the ability to actively control the passive movement available."

  • Active/Neural Contributing Factors: Concerns the deep stabilizer muscles rather than superficial ones.

    • Poor motor recruitment.

    • Poor muscular control/strength throughout the available range of motion (ROM).

    • Poor muscle endurance.

  • Passive Contributing Factors: These may reduce passive stability, requiring higher compensation from the active/neural systems.

    • Degenerative changes: For example, changes in discs with age affecting surrounding tissues.

    • Repetitive occupational positions, movements, or forces.

    • Acute trauma.

    • Poor posture.

  • Clinical Differentiation: True mechanical instability is diagnosed via objective measures such as end-range flexion/extension radiographs or specific ligamentous testing. Clinical instability focuses on functional control.

Clinical Presentation and Muscle Dynamics in Instability

  • Superficial vs. Deep Muscles: It is common to see hypertonic or hypertrophied superficial muscles in patients with clinical instability.

    • Compensatory Mechanism: Superficial muscles often attempt to compensate for weakness in deep stabilizing muscles.

    • Stiffness: This overactivity often leads patients to complain of feeling "stiff."

  • The Role of Stress and Sympathetic Response:

    • Stress (acute or chronic whiplash associated disorders or chronic pain) triggers the release of cortisol from the adrenal glands.

    • This stimulates a sympathetic response ("fight or flight").

    • Certain muscles become facilitated (superficial) while others are inhibited (deep) during this response.

    • Treatment Goal: Both superficial and deep muscles may need treatment, but the goals will differ (e.g., inhibition for superficial vs. activation for deep).

  • ICF Classification Differentiation (Olson): Olson sub-classifies "Neck Pain with Movement Coordination Impairments" into two distinct groups:

    • Clinical Instability.

    • Whiplash Associated Disorders (WAD).

Common Symptoms and Physical Findings (Cook 2005)

Based on a Delphi study of 172 experts, the following symptoms are hallmark indicators of instability:

  • Subjective Symptoms:

    • Intolerance to prolonged static postures.

    • Fatigue and an inability to hold the head up.

    • Feeling that the head feels heavy.

    • Relief with external support (e.g., hands, collar).

    • Frequent need for self-manipulation.

    • Feeling of instability, shaking, or lack of control.

    • Frequent episodes of acute attacks or sharp pain with sudden movements.

    • Neck catches, sticks, or locks during movement.

    • Relief in unloaded positions (e.g., lying down).

    • History of trauma.

    • Muscle tightness/stiffness.

    • Apprehension or fear of movement.

  • Physical Exam Findings:

    • Poor coordination and neuromuscular control.

    • Poor recruitment and dissociation of cervical segments during movement.

    • Abnormal or lax joint play.

    • Motion that is not smooth during active range of motion (AROM) assessment, including segmental hinging or aberrant movement.

Treatment Sequences and Interventions

  • Matching Interventions (Olson Text):

    • Coordination, strengthening, and endurance exercises.

    • Stretching exercises.

    • Mobilization/manipulation above and below hypermobile segments.

    • Ergonomic corrections.

  • Treatment Sequencing Strategies:

    • Goal: Enhance the active and neural subsystems while decreasing stressors on the passive subsystem.

    • Testing: Use physiologic motions as comparable signs and rely on functional subjective reports. To test for a hypothesis of poor eccentric control of Deep Neck Flexors (DNF) during extension, one might monitor control during the movement.

    • Initial Home Exercise Program (HEP): Low load dosed frequently (e.g., DNF and Deep Neck Extensor (DNE) activation, scapular retractions).

    • Progression: Advance targeted DNE/DNF stability, postural stability, and proprioception. Address contributory impairments with manual therapy (MT) and exercise. Re-test specifically with the weight of the head off-loaded or by cueing DNF.

Cervicogenic Dizziness (CGD)

  • Nature of Symptoms: Described as being "light-headed," "unsteady," or "off-balance." It is not true vertigo (spinning room).

  • Origin: Often results from the upper cervical spine and accompanies neck pain.

  • Diagnostic Challenges: It is a controversial phenomenon because there is no specific diagnostic test. Other causes of dizziness must be excluded first.

  • Anatomical Integration: The neck serves as the link between the head and body, requiring coordination across three systems:

    • Vestibular: Travels to the Vestibular Nuclei Complex (VNC) and cerebellum; efferents influence extraocular muscles, cervical movements, and balance.

    • Visual: Essential for the sense of self-motion at constant velocity.

    • Somatosensory: Provides the sense of body position in space; the cervical spine is unique because its somatosensory afferents have direct connections to the vestibular and visual systems.

  • Cervical Proprioceptive System: Rich in mechanoreceptors (especially muscle spindles in upper segments).

  • Relevant Reflexes:

    • Cervico-collic Reflex (CCR): Muscles react to stretch to stabilize the head on the body.

    • Cervico-ocular Reflex (COR): Complements the Vestibulo-ocular reflex (VOR) to stabilize vision, playing a larger role if vestibular loss is present.

Proposed Mechanisms and Treatment of CGD

  • Altered Somatosensory Input Hypothesis: The prevailing theory suggesting cervical dysfunction causes sensory mismatch:

    • Disturbed Head-Neck Awareness: Altered perception of head position relative to the neck.

    • Disturbed Neck Motor Control: Weak deep muscles and overactive superficial muscles.

    • Disturbed Postural Stability: Inability to use internal vestibular orienting info.

    • Disturbed Oculomotor Control: Affected smooth pursuit, saccades, and gaze stabilization.

    • Correction Note: Seniors and those with vestibular disorders show increased COR gain to compensate for decreased VOR gain; however, whiplash patients show increased COR gain without a corresponding decrease in VOR.

  • CGD Treatment Strategies:

    • Manual therapy and exercise for upper cervical joint or muscular restrictions.

    • Neuromuscular control and endurance training (DNF).

    • Postural re-education and balance training.

    • Cervicocephalic kinesthesia and coordination training.

    • Eye movement coordination training.

Indications for Cervical Surgery

Surgery should be reserved for:

  • Acute trauma (fractures/dislocation).

  • Persistent, progressive radicular or myelopathic signs (hard neurological signs) not responding to conservative management.

  • Timeline: Usually after at least 8−128-12 weeks of conservative care including physical therapy, medications, and injections.

Anterior Cervical Discectomy and Fusion (ACDF)

  • Approach: Antero-lateral.

  • Procedure: Used for lateral and central herniations. The disc is replaced with autograft (iliac crest) or allograft bone.

  • Outcome Fact: Outcomes are generally better when fewer levels are fused.

  • Rehab Progression for ACDF:

    • Phase 1 (Maximum Protection: 0–14 days): Goals include decreasing pain/edema and protecting the repair. Education on neck collars and mechanics. Cervical ROM/strengthening is contraindicated. Shoulder ROM limited to under 90∘90^{\circ}.

    • Phase 2 (Controlled Movement: 15–21 days): Improve ADLs and walking tolerance. Gentle upper extremity (UE) ROM still limited to 90∘90^{\circ}. Start lower back core strengthening.

    • Phase 3a (Reparative Phase: 4–8 weeks): Formal PT often starts here. Goals include nerve healing, preventing scar tissue, and cervical proprioception. Gentle STM to cervical spine, shoulder strength below 90∘90^{\circ}, and gentle initiation of DNF exercises.

    • Phase 3b (Return to Function: 9–12 weeks): Restoration of cervical ROM. Strengthening cervical extensors. Gentle isometrics and UE PNF patterns. Shoulders can progress above 90∘90^{\circ}.

    • Phase 3c (Return to Function: 13–52 weeks): Maximize function and restore strength/endurance. Functional retraining for work/sport per physician approval.

Laminectomy and Foraminotomy

  • Laminectomy:

    • Indication: Spinal stenosis.

    • Procedure: Resection of the lamina (partial or total).

    • Precautions: Posterior approach requires caution with posterior tissue STM. Some mobilizations are contraindicated due to surgical altered anatomy.

    • Complications: Can lead to hypermobility, instability, chronic myofascial pain, and occipital headaches (due to the body attempting to stabilize the area).

  • Foraminotomy:

    • Indication: Widening the intervertebral foramen to relieve specific nerve compression.

    • Details: Less invasive than laminectomy. Stability is maintained as facet joints and major ligaments are preserved.

    • Rehab: Less complicated with fewer precautions.

General Post-Surgical Management Principles

  • Anatomical Awareness: Know the specific procedure to determine caution levels.

  • Examination: Perform a thorough exam similar to non-operative patients while respecting surgical precautions.

  • Chronic Pain Factors: Address central sensitization and psychosocial components, which are common after repeated surgeries.