Clinical Examination

The short version

The examination uses a clever trick. The inner ear and the neck both send "where is my head" signals to the brain. If you can stimulate the neck while keeping the inner ear still — by rotating the body under a fixed head — and the patient gets dizzy, the dizziness must be coming from the neck.

Four short tests do most of the work:

• Cervical Torsion Test — patient on a swivel chair, head held still, body rotated 45–90° and held for 30 seconds. Watch for symptoms.
• Head-Neck Differentiation Test — compare what happens when only the head turns vs only the body turns.
• SPNT — the patient tracks a moving target with their eyes, first with the body straight, then with the body rotated. A pursuit that gets worse with body rotation is cervicogenic.
• Joint Position Error — a laser on the patient's head shows whether they can return their head to neutral after a rotation, with their eyes closed.

The principle of differential stimulation

The vestibular labyrinth and the cervical proprioceptive system both signal head position, and their outputs converge at the vestibular nuclei (Module 2, Fig. 2.3). At the bedside this convergence is a problem — symptoms from one source mimic symptoms from the other. The way around the problem is to design provocations that stimulate one channel while holding the other still:

• Move the head in space → stimulates labyrinth and neck together.
• Move the head on the trunk while the head stays still in space → stimulates the labyrinth without the neck. (Hard to achieve in practice; requires careful examiner support and slow accelerations.)
• Move the trunk under a still head → stimulates the neck while leaving the labyrinth completely undisturbed. This is the cleanest cervical-only provocation.

The Cervical Torsion Test and the Head-Neck Differentiation Test both rest on the third manoeuvre.

The Cervical Torsion Test

The patient sits on a swivel chair. The examiner stabilises the head with both hands so that it remains in neutral throughout. The chair (and therefore the trunk) is rotated to one side — typically 45° initially, up to 90° — and held there for at least 30 seconds. The manoeuvre is then repeated to the opposite side.

Because the head is held still, neither the semicircular canals nor the otoliths register a meaningful stimulus during sustained torsion. Reproduction of vertigo, lightheadedness, visual disturbance, or unsteadiness during the hold supports a cervical or vascular contribution.

The Head-Neck Differentiation Test

The two scenarios are run sequentially and the patient's symptoms compared:

The differentiation works because scenario B — trunk-under-head — is anatomically the closest the bedside can come to a pure cervical stimulus. Symptoms in B without symptoms in A would be unusual (since A always also stimulates the cervical system) but symptoms in both, with a clear amplification in B, suggest a cervical contribution.

Smooth Pursuit Neck Torsion (SPNT)

The SPNT, introduced by Tjell & Rosenhall, takes the principle one step further by quantifying eye-movement performance in neutral versus torsion.¹⁶ The patient tracks a target moving horizontally at roughly 20°/sec; pursuit gain (eye velocity / target velocity) is measured in neutral and again with the body rotated 45° to each side. The test parameter is the SPNT difference:

SPNT difference = neutral gain − mean torsion gain

In the original study, a difference above approximately 0.10 discriminated whiplash-associated dizziness from central and peripheral vestibular causes with 90% sensitivity and 91% specificity in the WAD-with-dizziness group.¹⁶

Joint Position Error (Revel test)

A head-mounted laser projects onto a target board 90 cm away. With eyes open, the patient establishes neutral. With eyes closed, the patient actively rotates the head fully to one side and then returns to perceived neutral. The error — the distance between the original neutral and the returned-to position — is the cervicocephalic joint position error.¹⁷

Six trials are averaged. Revel's original cutoff was approximately 4.5°; persistent whiplash patients with dizziness consistently exceed 6° and show errors of 7–10° in some series.^18,19

Interpretation in practice

1. No test stands alone

Cervicogenic dizziness lacks a gold standard, and every bedside test in this module has imperfect specificity in real clinical populations.²⁰ The clinical reasoning is to assemble a battery of cervical-isolating provocations and weigh the pattern of results against the differential. A positive SPNT in a patient with a normal vHIT, normal caloric responses, and an exam reproducing dizziness on the Cervical Torsion Test is a much stronger signal than any one of those findings alone.

2. Reliability is movement-direction dependent

Joint position error is reliably measurable after cervical rotation in both directions; reliability for flexion and extension is more variable.²¹ When reporting JPE in a patient record, specify the movement direction and the number of trials.

3. Asymmetric findings deserve attention

A constant error favouring one direction — for example, all returns biased to the left — is more interesting than a large absolute error with no directional pattern. The signed (constant) error often points to which cervical segment is contributing, since proprioceptive deficit tends to bias relocation toward the side of restriction.

4. The four tests together

The pragmatic order at the bedside, after history and a standard neurological screen:

1. Joint Position Error first — it is quiet, sets a quantitative baseline, and screens for proprioceptive deficit before any provocation.
2. SPNT next, ideally with VNG if available — the most specific single test in the WAD-with-dizziness population.¹⁶
3. Head-Neck Differentiation as a low-cost bedside screen, particularly when symptoms are reproducible but the origin is uncertain.
4. Cervical Torsion Test last — it is the most provocative, has a longer hold, and carries the rotational vertebral artery caveat. Reserve for cases where the prior tests have built a coherent cervical picture.

5. What the examination does not tell you

A positive battery confirms that the cervical proprioceptive system is disordered. It does not, by itself, tell you whether that disorder is the cause of the dizziness or simply a coexisting finding. The interpretive leap from "cervical signal is abnormal" to "cervical signal is the source of this patient's symptoms" is made by combining the test results with the history (mechanical neck pain that consistently precedes or co-fluctuates with the dizziness), the rest of the vestibular workup (which must be unrevealing), and the response to a treatment trial aimed at the cervical spine.