Case Presentation: A 23-year-old male with no past medical history presented with neck pain and bilateral arm paresthesia of four-week duration. The patient was prescribed ibuprofen, and an MRI cervical spine was ordered. The MRI showed multilevel degenerative disc disease, and the patient was referred to physical medicine and rehabilitation. In the weeks prior to the appointment, the patient’s symptoms progressed to include bilateral forearm weakness, muscle spasms, low back pain, tingling in the right big toe, and intermittent right quadricep spasms. Physical exam was significant for limited neck flexion and diminished strength in the left extensor hallucis longus, ankle evertor, and hip abductors. The patient was diagnosed with C6-C7 and L5 radiculopathies, advised to continue taking ibuprofen, and given posture improvement exercises. Despite implementing these exercises, the patient grew weaker and experienced more frequent paresthesia and muscle twitching in his extremities. Low back pain, toe numbness, fatigue, and hypersomnia also progressed. He presented to the emergency room, at which time MRIs of the thoracic and lumbar spine were performed without notable findings. The patient was referred to neurology and a broad blood panel was obtained. Blood tests were significant for low B12 at 200 pg/mL and an elevated methylmalonic acid at 1,120 nmol/L. The patient was not anemic with a red blood cell, hemoglobin, and hematocrit count of 4.93 M/uL, 14.0 g/dL, and 43.1% respectively. A more detailed history revealed the patient was a lifelong vegetarian. After completing an extensive workup to rule out infectious, inflammatory, and autoimmune etiologies, the patient was diagnosed with a Vitamin B12 deficiency and was treated with oral B12 and subcutaneous B12 injections. The patient saw gradual improvement and was symptom-free in 10 months. Cobalamin levels 7 months after the start of supplementation were 961 pg/mL.

Discussion: Vitamin B12 is required for the formation of hematopoietic cells and the synthesis of myelin.[1] Low B12 can cause megaloblastic anemia and prolonged deficiency can cause neurological symptoms.[2] This case highlights the challenges of diagnosing B12 deficiency due to its variable and nonspecific presentation. The most common initial symptom is fatigue.[3] Linking fatigue to B12 is difficult because fatigue has numerous etiologies.[4] Current guidelines recommend clinicians obtain complete blood counts for patients with fatigue. While a typical B12 deficiency would have anemia prompting further workup, this patient had normal levels. Neurologic symptoms of B12 deficiency are also nonspecific.[5] This patient initially complained of upper extremity paresthesia which was misdiagnosed as cervical radiculopathy. This case demonstrates the risks of prematurely attributing clinical symptoms to potentially nonspecific spinal imaging. A review found 37% of asymptomatic 20-year-olds had disk degeneration.[6] Misattributing neurologic symptoms to spinal disk injury is dangerous in patients with low B12 because delayed treatment can cause permanent spinal cord injury.

Conclusions: We strongly recommend testing for B12 deficiency in all vegetarians and vegans presenting with neurologic symptoms or fatigue. While B12 deficiency remains rare in developed countries, it is plausible cases will rise with the increased adoption of veganism. Clinicians should be familiar with its presentation due to the serious and potentially irreversible complications of untreated disease.