Phosphorylated neurofilament subunit levels in the serum of cervical compressive myelopathy patients

We investigated the serum levels of the phosphorylated form of the high molecular weight neurofilament subunit (pNF-H) in patients with cervical compressive myelopathy. pNF-H is becoming increasingly recognized as a biomarker for axonal injury, however, it remains unclear whether serum pNF-H is elevated in chronic spinal cord compression. We examined 26 patients who underwent surgery for cervical compressive myelopathy. Peripheral blood samples were obtained both preoperatively and 1 week after surgery to evaluate the serum pNF-H levels using an enzyme-linked immunosorbent assay. A history of recent aggravation of myelopathy was also investigated. Of the 26 myelopathy patients, the preoperative serum pNF-H level was negative in 20 patients and moderately elevated in six. Patients who were positive for pNF-H were more likely to have had a recent aggravation of myelopathy compared with the pNF-H negative patients (83 versus 25%; p = 0.02). All patients who were positive for pNF-H before surgery remained positive after surgery. Two patients who became positive after surgery demonstrated a neurologic deterioration associated with the surgery. In conclusion, the serum pNF-H level was negative in the majority of patients with cervical compressive myelopathy. Our results suggest that an elevated serum level of pNF-H is associated with an acute worsening of myelopathy and that a positive conversion of pNF-H after surgery is a marker of perioperative neural damage.