F wave in restless legs syndrome, as an electrophysiological response of clinical relief

ABSTRACT

Objective

The study aimed to evaluate the impact of postural changes on the F wave-related parameters and whether those changes were associated with clinical relaxation, which was achieved in restless legs syndrome patients with standing up.

Methods

F wave duration (FWD), compound muscle action potential duration (CMAPD), and FWD/CMAPD ratio were evaluated in supine and upward positions in 18 restless legs syndrome patients and compared with 18 age and gender-matched healthy volunteers.

Results

FWD/CMAPD was significantly higher for the tibial nerve at supine position (p = 0.043) but not at upright position (p = 0.206) and for ulnar nerve, both at supine (p = 0.007) and upright positions (p = 0.023) in RLS patients compared to controls. Ulnar FWD decreased significantly at the upright position in both control and RLS patients (p = 0.035, p = 0.028, respectively). CMAPD decreased only in the control group with standing up for both ulnar and tibial nerves (p = 0.048, p = 0.017, respectively).

Discussion

Ulnar and tibial FWD/CMAPD ratios increased in RLS patients compared to controls. However, FWD/CMAPD was not affected by the posture within the groups. Postural change seems to be a factor that decreased ulnar FWD both in RLS patients and the control group. Ulnar and tibial CMAPD reduced only in healthy controls with an upright position. Tibial and ulnar FWD/CMAPD ratios are favorable electrophysiological parameters diagnosing RLS. The tibial FWD/CMAPD ratio loses its significance only when the patient stands up, reflecting the clinical relief achieved with the postural change.

KEYWORDS:

• Restless legs syndrome
• F wave
• electrophysiology
• nerve conduction study

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

The datasets generated and analyzed during the current study are available from the corresponding author on reasonable request.

Geolocation information

Ankara City hospital, electrophysiology laboratory, WQ24+FP Çankaya, Ankara, Turkey

Additional information

Funding

This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.

Notes on contributors

Safiye Gul Kenar

Safiye Gul Kenar, who received her neurology specialization from Gazi University in 2014, works as a specialist doctor in Ankara City Hospital and serves in the electrophysiology laboratory and outpatient clinic.

Ebru Bilge Dirik

Ebru Bilge Dirik, who received her neurology specialization from Ankara University in 2004, works as a specialist doctor in Ankara City Hospital and serves in movement disorders outpatient clinic.

Gorkem Tutal Gursoy

Gorkem Tutal Gursoy Gursoy, who received her neurology specialization from Baskent University in 2011, works as a specialist doctor in Ankara City Hospital and serves in the dementia outpatient clinic.

Nuriye Kayali

Nuriye Kayali, who received her neurology specialization from Gazi University in 2015, works as a specialist doctor in Ankara City Hospital and serves the general outpatient clinic.

Sule Bilen

Sule Bilen, who received her neurology specialization from Ankara Numune Training and Research Hospital in 2003, works as an associate professor in Ankara City Hospital and serves in the electrophysiology laboratory and neuromuscular diseases outpatient clinic.