Can C8 (cervical spine nerve root) impingement cause dizziness or vertigo?

C8 Nerve Root Impingement Does Not Cause Dizziness or Vertigo

C8 nerve root impingement is not a recognized cause of dizziness or vertigo. The C8 nerve root innervates the hand and forearm, and compression at this level produces motor and sensory deficits in the upper extremity, not vestibular symptoms.

Anatomical and Physiological Basis

The mechanisms proposed for cervical spine-related dizziness involve the upper cervical spine (C1-C3), not the lower cervical spine where C8 is located:

• Proprioceptive cervicogenic dizziness results from impaired cervical proprioception affecting sensorimotor control, primarily from upper cervical dysfunction 1, 2
• Rotational vertebral artery compression occurs when osteophytes at the mid-portion of vertebral arteries (typically at C1-C2 levels) obstruct flow during head turning 3, 1
• Studies documenting cervical spine dysfunction as a cause of vertigo specifically identify C1 (14 cases), C2 (6 cases), and C3 (4 cases) as the affected levels—not C8 4

Clinical Evidence for Upper Cervical Involvement Only

When cervical spine pathology does contribute to dizziness, the pattern is distinct:

• Dizziness associated with neck pain in patients with upper cervical pathology, not lower cervical nerve root compression 5
• Symptoms are provoked by head turning or neck movements that affect upper cervical proprioceptors or vertebral artery flow 3, 1
• The cervical spine's role in dizziness reflects its contribution to sensorimotor control along with visual and vestibular input, which requires intact upper cervical proprioception 2

What C8 Impingement Actually Causes

C8 nerve root compression produces:

• Motor deficits: Weakness of finger flexors, hand intrinsic muscles
• Sensory deficits: Numbness/paresthesias in the medial forearm and ulnar aspect of the hand
• Reflex changes: No specific reflex loss (C8 has no associated deep tendon reflex)

Critical Diagnostic Considerations

If your patient has both C8 radiculopathy symptoms AND dizziness:

• These are separate, unrelated conditions requiring independent evaluation 6, 7
• Dizziness requires systematic classification by timing and triggers: brief episodic (seconds), acute persistent (days), or chronic (weeks to months) 6, 8
• Red flags requiring urgent imaging include focal neurological deficits beyond the C8 distribution, sudden hearing loss, inability to stand/walk, or new severe headache 6
• Consider common causes of dizziness: BPPV, vestibular neuritis, Ménière's disease, vestibular migraine, medication side effects, anxiety/panic disorder, or posterior circulation stroke 6, 7, 8

When to Consider Cervical Contribution to Dizziness

Only consider cervicogenic dizziness if:

• Upper cervical spine dysfunction (C1-C3) is documented on examination 4, 5
• Dizziness correlates temporally with neck pain and neck movements 2, 5
• Other vestibular, neurological, and psychosomatic causes have been excluded 1, 5
• Manual therapy combined with vestibular rehabilitation is the treatment of choice for confirmed cervicogenic dizziness 8, 5