Microconvex Probe-Assisted Sonopalpation for Ultrasound-Guided Diagnosis of Cervical Discogenic Pain in Challenging Neck Anatomy: A Technical Report.

Cervical discogenic pain is diagnostically challenging because degenerative changes on magnetic resonance imaging often do not reliably identify the symptomatic disc level. Although provocative discography remains an important reference standard in selected patients, it is invasive and controversial. More recently, ultrasound-guided sonopalpation has been described as a practical adjunct for identifying painful cervical discs before intradiscal intervention. However, in patients with short necks, bulky anterior soft tissues, reduced tissue compliance, or close apposition of the carotid sheath to the thyroid-tracheal complex, conventional finger-based sonopalpation may be technically difficult or impossible. This technical report describes a focused modification of previously published methods: use of the vertex of a small-footprint microconvex transducer as the sonopalpation instrument itself. After standard ultrasound localization of the target cervical level, the probe is advanced into the sagittal plane between the carotid sheath and the thyroid-tracheal complex under real-time visualization. The curved apex of the transducer is then used to apply graded focal pressure through the longus colli and through the longus capitis when appropriate at more cephalad levels, to the anterolateral annulus fibrosus while the patient is asked whether concordant pain is reproduced. If intervention is planned, the same transducer may then be used for subsequent ultrasound-guided disc access according to previously described medial cervical approaches. In our practical setup, the patient may be examined in the seated position while facing the ultrasound screen, with the operator standing behind the patient. This arrangement allows real-time patient feedback and may help reproduce the patient's usual mechanical pain state through gravitational loading of the head and cervical spine during focused disc compression. This modification extends prior ultrasound-guided cervical disc techniques by allowing the microconvex probe to function not only as an imaging device and tissue separator, but also as a direct palpation tool. Its potential advantages are improved access in difficult anatomy, simultaneous tissue displacement and symptom provocation, and continuous visualization of critical structures. The principal trade-off is reduced tactile feedback compared with digital palpation. Further clinical study is needed to define reproducibility, diagnostic value, and safety.