Characteristics of late responses in S1 radiculopathy

Electrophysiological research methods, in particular late nerve conduction responses, play an important role  n the diagnosis of a number of neurogenic disorders and, in particular in lumbosacral radiculopathy. Late responses include the F-wave, H-reflex, and A-wave.

The purpose of this study was to determine the diagnostic value of late responses to tibial nerve stimulation in patients with isolated S1 radiculopathy in comparison with clinical findings. We examined 32 patients with isolated S1 radiculopathy (16 women, 16 men), their average age was 43.5 ± 9.3 years.

An electroneuromyographic study of the tibial nerve on the injured side revealed the presence of an A-wave in 20 patients (62.5 %, p < 0.001). It was significantly more often combined with tests for spinal root irritation, and its localization before the F-wave was a characteristic feature of this pathology. The analysis of the F-wave parameters showed an increase  in its duration (p = 0.001) compared to the uninjured side, and compared to the control group there was a prolongation of both duration and latency (p < 0.001). Patients with the presence of an A-wave had more pronounced changes in the duration  and latency of the F-wave on the injured and uninjured sides. When analyzing the H-reflex, it was found to be absent  in 14 (43.8 %) and decreased in amplitude in 9 (28.1 %) patients on the injured side. The absence of the H-reflex was significantly more often detected in patients with the absence of the Achilles reflex (p < 0.05). The number of patients with the presence of an A-wave did not differ from that of patients with an increased duration of the F-wave or a decrease in the amplitude of the H-reflex (p > 0.05).

1. Fisher M. A. Electrophysiology of radiculopathies. Clinical Neurophysiology, 2002, vol. 113, no. 3, pp. 317–335. https://doi.org/10.1016/S1388-2457(02)00018-4

2. Panayiotopoulos C. P., Chroni E. F-waves in clinical neurophysiology. Electroencephalography and Clinical Neurophysiology, 1996, vol. 101, no. 5, pp. 365–374. https://doi.org/10.1016/0924-980X(96)95635-0

3. Mauricio E. A., Dimberg E. L., Rubin D. I. Utility of minimum F-wave latencies compared with F-estimates and absolute reference values in S1 radiculopathies: are they still needed? Muscle and Nerve, 2014, vol. 49, no. 6, pp. 809–813. https://doi.org/10.1002/mus.23992

4. Yousif S., Ahmed A., Abdelhai A., Musa A. Nerve conduction studies in patients with lumbosacral radiculopathy caused by lumbar intervertebral disc herniation. Advances in Orthopedics, 2020, vol. 2020, art. ID 8882387. https://doi.org/10.1155/2020/8882387

5. Khodulev V. I., Kobylko O. V., Kovalev A. A. Clinical and electroneuromyographic characteristics of patients with isolated S1 radiculopathy. Meditsinskie novosti [Medical news], 2023, vol. 347, no. 8, pp. 54–57 (in Russian).

6. Nobrega J. A. M., Pinheiro D. S., Manzano G. M., Kimura J. Various aspects of F-wave values in a healthy population. Clinical Neurophysiology, 2004, vol. 115, no. 10, pp. 2336–2342. https://doi.org/10.1016/j.clinph.2004.05.011

7. Zheng C., Liang J., Nie C., Yu Z., Feizhou L., Jianyuan J. F-waves of peroneal and tibial nerves in the differential diagnosis and follow-up evaluation of L5 and S1 radiculopathies. European Spine Journal, 2018, vol. 27, no. 8, pp. 1734–1743. https://doi.org/10.1007/s00586-018-5650-9

8. Toyokura M., Furukawa T. F wave duration in mild S1 radiculopathy. Clinical Neurophysiology, 2002, vol. 113, no. 8, pp. 1231–1235. https://doi.org/10.1016/S1388-2457(02)00148-7

9. Puksa L., Stålberg E., Falck B. Occurrence of A-waves in F-wave studies of healthy nerves. Muscle and Nerve, 2003, vol. 28, no. 5, pp. 626–629. https://doi.org/10.1002/mus.10448

10. Fang J., Cui L., Liu M., Guan Y., Ding Q., Shen D., Li D., Tai H. A retrospective study of the characteristics and clinical significance of A-waves in amyotrophic lateral sclerosis. Frontiers in Neurology, 2017, vol. 8, art. 515. https://doi.org/10.3389/fneur.2017.00515

11. Bischoff C., Stålberg E., Falck B., Puska L. Significance of A-waves recorded in routine motor nerve conduction studies. Electroencephalography and Clinical Neurophysiology, 1996, vol. 101, no. 6, pp. 528–533. https://doi.org/10.1016/S0921-884X(96)96553-4

12. Srotova I., Vlckova E., Dusek L., Bednarik J. A-waves increase the risk of developing neuropathy. Brain and Behavior, 2017, vol. 7, no. 8, p. e00760. https://doi.org/10.1002/brb3.760

13. Magistris M. R., Roth G. Motor axon reflex and indirect double discharge: ephaptic transmission? A reappraisal. Electroencephalography and Clinical Neurophysiology, 1992, vol. 85, no. 2, pp. 124–130. https://doi.org/10.1016/01685597(92)90078-P

14. Sartucci F., Bocci T., Borghetti D., Orlandi G., Manfredonia F., Murri L., Giannini F., Rossi A. Further insight on A-wave in acute and chronic demyelinating neuropathies. Neurological Sciences, 2010, vol. 31, no. 5, pp. 609–616. https:// doi.org/10.1007/s10072-010-0354-x

15. Khodulev V., Ovsiankina G., Zobnina G. A-wave as a sign of peripheral nervous system demyelination. European Journal of Neurology, 1998, vol. 5, suppl. 3, p. S46. https://doi.org/10.1111/j.1468-1331.1998.tb00464.x

16. Khodulev V., Kabylka A., Klimko A. Significance of A-waves in isolated calf pain as a manifestation of radicular pain during F-wave studies: a case report. Cureus, 2023, vol. 15, no. 2, p. e35254. https://doi.org/10.7759/cureus.35254

17. Rowin J., Meriggioli M. N. Electrodiagnostic significance of supramaximally stimulated A-waves. Muscle and Nerve, 2000, vol. 23, no. 7, pp. 1117–1120. https://doi.org/10.1002/1097-4598(200007)23:7<1117::AID-MUS16>3.0.CO;2-#

18. Rampello L., Rampello L., Arcidiacono A., Patti F. A waves in electroneurography: differential diagnosis with other late responses. Neurological Sciences, 2020, vol. 41, no. 12, pp. 3537–3545. https://doi.org/10.1007/s10072-020-04649-2

19. Albeck M. J., Taher G., Lauritzen M., Trojaborg W. Diagnostic value of electrophysiological tests in patients with sciatica. Acta Neurologica Scandinavica, 2000, vol. 101, no. 4, pp. 249–254. https://doi.org/10.1034/j.1600-0404.2000.09005.x

20. Khodulev V. I., Kobylko O. V. The combined duration of the composite F-wave population is a new electroneuro-myographic parameter in the study of radiculopathies. Klinicheskaya neirofiziologiya i neiroreabilitatsiya: materialy Vos’moi nauchno-prakticheskoi konferentsii s mezhdunarodnym uchastiem, Sankt-Peterburg, 12–13 noyabrya 2020 goda [Clinical neurophysiology and neurorehabilitation: Proceedings of the Eighth scientific and practical conference with international participation, St. Petersburg, November 12–13, 2020]. St. Petersburg, 2020, pp. 132‒133 (in Russian).

21. Espiritu M. G., Lin C. S.-Y., Burke D. Motoneuron excitability and the F wave. Muscle and Nerve, 2003, vol. 27, no. 6, pp. 720–727. https://doi.org/10.1002/mus.10388