BACKGROUND Patients with Arnold-Chiari Malformation I (CM-I) treated with foramen magnum decompression (FMD) can have ongoing neck pain, headaches, and other symptoms complicated by persistent syringomyelia, yet there is little research regarding treatment of these symptoms. CASE REPORT A 62-year-old woman with a history of residual syringomyelia following FMD and ventriculoperitoneal shunt for CM-I presented to a chiropractor with progressively worsening neck pain, occipital headache, upper extremity numbness and weakness, and gait abnormality, with a World Health Organization Quality of Life score (WHO-QOL) of 52%. Symptoms were improved by FMD 16 years prior, then progressively worsened, and had resisted other forms of treatment, including exercises, acupuncture, and medications. Examination by the chiropractor revealed upper extremity neurologic deficits, including grip strength. The chiropractor ordered whole spine magnetic resonance imaging, which demonstrated a persistent cervico-thoracic syrinx and findings of cervical spondylosis, and treated the patient using a multimodal approach, with gentle cervical spine mobilization, soft tissue manipulation, and core and finger muscle rehabilitative exercises. The patient responded positively, and at the 6-month follow-up her WHO-QOL score was 80%, her grip strength and forward head position had improved, and she was now able to eat using chopsticks. CONCLUSIONS This case highlights a patient with neck pain, headaches, and persistent syringomyelia after FMD for CM-I who improved following multimodal chiropractic and rehabilitative therapies. Given the limited, low-level evidence for these interventions in patients with persistent symptoms and syringomyelia after FMD, these therapies cannot be broadly recommended, yet could be considered on a case-by-case basis.