Rare variant of cervical conjoined nerve root confirmed during full endoscopic cervical foraminotomy: illustrative case.

backgroundDiagnosing cervical radiculopathy with root anomalies is difficult, as cervical nerve root anomalies are rare. Here, the authors report the rare case of a conjoined nerve root variant confirmed using full endoscopic cervical foraminotomy (FECF). OBSERVATIONS: A 40-year-old female presented with painful numbness and paresis in the right upper limb. Physical examination revealed multiple radiculopathies in the C6 and C7 nerve roots. However, magnetic resonance imaging and computed tomography did not reveal any lesions explaining the right C7 radiculopathy. Furthermore, the right C6 root block injection had no effect, whereas the right C7 root block injection was extremely effective. FECF revealed a conjoined nerve root variant in the right C6-7 intervertebral foramen. LESSONS: The study revealed that single nerve root block injections can be useful for pain relief as well as diagnosis of the affected level. Although the current case is rare, the report revealed that a lesion at a single intervertebral foramen can cause multiple radiculopathies. The study also highlighted the importance of careful examination of the clinical symptoms and the limitations of imaging tools. https://thejns.org/doi/10.3171/CASE24752.