To analyse the Intraoperative neuromonitoring (IONM) data of patients with degenerative cervical myelopathy (DCM) undergoing cervical laminectomy and assess the incidence of signal drops and their risk factors. A retrospective observational study of patients with DCM who underwent cervical laminectomy with IONM between July 2018 to March 2023 were included. We analysed the signal changes for any correlation with the type of pathology (OPLL vs CSM), clinical(severity of myelopathy, duration of symptoms) and radiological parameters(length of cord signal changes and K-line). Out of the 100 DCM cases, 55 were diagnosed with Ossified posterior longitudinal ligament (OPLL) and 45 as Cervical spondylotic myelopathy (CSM). Signal drops were recorded in 26 patients - 14 persistent drops and 12 transient drops. True positive drops were seen in 4 patients (2 OPLL and 2 CSM) out of which 3 had sustained bimodal drops(both SSEP and MEP). Incidence of signal drops were significantly higher with OPLL compared to CSM (p-value < 0.01). 10/14 persistent signal drops and 9/12 transient drops were seen in patients in OPLL. Continuous OPLL, negative K line, hill type OPLL, severity of myelopathy and longer duration of symptoms were risk factors for signal drops. Patients with cervical OPLL have a higher incidence of false positive and transient signal drops after decompression compared to CSM. Longer duration of symptoms, high grade myelopathy, continuous OPLL, hill type lesion and negative K-line were risk factors for signal drops.