Comparing Michigan Neuropathy Screening Instrument Score with Plantar Sensory Nerve Conduction Study in Diabetic Neuropathy.

Objective: To compare the Michigan Neuropathy Screening Instrument (MNSI) score and plantar sensory nerve conduction study (NCS) in diabetic patients with neuropathy.

Study design: Comparative study. Place and Duration of the Study: Department of Neurology, Liaquat National Hospital, Karachi, from March to August 2024.

Methodology: Using a non-probability purposive sampling technique, patients aged between 16 and 65 years with diabetic polyneuropathy and age-method healthy controls were included in the study. Neuropathy was graded based on MNSI score. Sural and plantar NCS were performed using the standard and modified Ponsford techniques, respectively. All evaluations were performed using a Nihon Kohden electromyography system to ensure reliable results. Data were collected using a well-designed questionnaire administered by neurology trainees and later analysed by SPSS version 27.

Results: A total of 78 participants, comprising 53 diabetic patients (33 MNSI-positive, 20 MNSI-negative) and 25 age-matched healthy controls, were analysed. MNSI-positive patients had significantly higher HbA1c and fasting blood sugar (FBS) levels compared to MNSI-negative patients with p = 0.005 and p = 0.001, respectively. The sural nerve conduction abnormalities were found in 39.7% participants, while 51.3% participants showed plantar nerve conduction abnormalities. There was a notable association between higher MNSI score and abnormal plantar NCS (p = 0.001), with significantly reduced amplitudes and conduction velocities in MNSI-positive patients, highlighting their sensitivity in detecting diabetic polyneuropathy. Additionally, lower amplitudes in the MNSI-negative group indicated their potential for identifying subclinical diabetic peripheral neuropathy (DPN).

Conclusion: The comparison of MNSI score with plantar sensory nerve conduction studies demonstrates that integrating both methods enhance the detection of early diabetic neuropathy.

Key words: Diabetic peripheral neuropathy, Plantar nerve conduction studies, sural nerve conduction studies, Michigan Neuropathy Screening Instrument, Glycated haemoglobin.