Objective: To assess peripheral NP occurrence and clinico-electrophysiological features in patients with advanced PD patients treated with continuous subcutaneous fLD/fCD.

Background: Continuous subcutaneous fLD/fCD is effective for advanced PD. Peripheral NP has mainly been described with levodopa-carbidopa intestinal infusion, whereas reported adverse events with subcutaneous fLD/fCD have primarily focused on infusion-site reactions.

Method: We conducted a prospective monocenter observational study in patients with advanced PD treated with continuous subcutaneous fLD/fCD. All subjects were evaluated using nerve conduction studies (NCS) before treatment initiation and at 1 year after. Clinical, electrophysiological, and biological data were collected.

Results: Twenty-six patients were included (mean age 68.8 ± 9.7 years). Baseline mean MDS-UPDRS part III score was 31.5 ± 11.2, mean Hoehn and Yahr stage was 3.0 ± 0.9, and mean LEDD increased from 1520.6 ± 741.2 to 1965.1 ± 987.8 mg/day (+444.5 mg/day). Peripheral NP was identified in 5/26 patients (19.2%). At baseline, 2 patients had normal NCS, 2 had asymptomatic sensory axonal polyNP, and 1 had asymptomatic sensory neuronopathy. During follow-up, 2 patients became symptomatic: one after 3 months, with painful sensory symptoms in the setting of a pre-existing sensory neuronopathy, and one after 5 months despite a normal baseline assessment. At 1 year, systematic NCS revealed a severe NP in 1 additional patient with a normal baseline study and worsening of 2 pre-existing asymptomatic NP. NP was predominantly sensory axonal and painful in 2/5 patients. Vitamin B6 or B9 deficiency was present before treatment initiation in 2/5 patients, and 1 patient developed vitamin B6 deficiency during follow-up. After supplementation, NP remained stable clinically and electrophysiologically, but fLD/fCD dose reduction was necessary in 3/5 patients, including 1 with subsequent motor worsening. No patient discontinued treatment because of NP.

Conclusion: Peripheral NP was detected more frequently in this cohort than in pivotal and open-label studies. It may be symptomatic, with sensory and painful features, or remain clinically silent and be detected only through systematic electrophysiological monitoring. These findings support regular clinical, electrophysiological, and metabolic monitoring in these patients.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/peripheral-neuropathy-np-in-advanced-parkinsons-disease-pd-patients-treated-with-continuous-subcutaneous-foslevodopa-foscarbidopa-fld-fcd/