Discussion
0.1–0.5% of people are affected by AS, and it is defined by radiographic sacroiliitis, inflammatory back pain, excess spinal bone formation, and positive HLA-B27 in most cases (6, 7). AS spondyloarthropathy features are associated with human leukocyte antigen (HLA)-B27 (8, 9). Positive HLA-B27 AS patients are susceptible to younger AS cases, have a higher uveitis frequency, better response to management with tumor necrosis factor-alpha (TNF-α) inhibitors, and have a lower IBD or psoriasis prevalence (10).
Pain  is the AS main symptom known as one inflammatory pain (IP) (11). Although, AS subjects’ pain always does not relate to the inflammatory indexes, including erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) (12).
Chronic inflammatory arthritis patients like AS with peripheral neuropathy is an infrequent condition. Peripheral nerve involvement is one extra-articular rare striking AS involvement, and maybe it has no association with the clinical variables (13). Furthermore, in asymptomatic AS patients, the involvement of the peripheral nervous system can be the central nervous system (4).
A case-report study showed a case with swelling in his knees and ankles, chronic pain, and neck and low back pain. The patient additionally had tingling and numbness in his hands and feet. On examination, he has impaired sensation, muscle wasting, weakness, absent ankle jerks, and equivocal plantar response. EMG suggests chronic demyelinating polyneuropathy with secondary axonal involvement. Additionally, the patient has a positive HLA-B27 and microcytic hypochromic anemia (13). Their study involved patient who, like ours, had developed neuropathy, but the type of neuropathy differed.
In addition, another study investigated the relationship between peripheral neuropathy and AS by evaluating the peripheral nervous system of 32 AS patients without symptoms of neuropathy. The study found that 18.8% of the AS patients had sensory or sensorimotor peripheral nerve involvement, and 21.9% had focal nerve involvement. The study also found correlations between tibial nerve motor conduction velocity and Schober and chest expansion tests and negative correlations between sural nerve sensory action potential amplitude and age and disease duration. The study suggests that asymptomatic AS patients can have peripheral nervous system involvement, and further studies are needed to confirm the results and evaluate the clinical significance (4). The results of their study were in line with ours, but their cases did not have any symptoms of neuropathy, while ours did.
In summary, our case report presented a case of AS under medication with a rare peripheral neuropathy presentation. Our case report differs from previous studies and case reports.