Lower motor neuron degeneration in HSP?

Findings of electrophysiological studies


Signs of lower motor neuron dysfunction were found in this study of people with HSP and PLS via electrophysiological markers. The electrophysiological findings may be explained by degeneration spreading to the lower motor neurons, thus contributing to disease progression.


Introduction: The present study is an examination of possible subclinical involvement of lower motor neuron (LMN) in patients with primary lateral sclerosis (PLS) and hereditary spastic paraparesis (HSP) electrophysiologically.

Methods: Nine PLS patients and 5 HSP patients were prospectively analyzed. Jitter measurement with concentric needle electrode (25 mm, 30 G) (CN-jitter) recorded from right extensor digitorum muscle during voluntary contraction with 1 kHz high-pass frequency filter set. European Myelopathy Score (EMS) was used to evaluate disability. The relationship between disability score and jitter values was investigated.

Results: HSP patients had suffered from the disease for longer period of time (p<0.001). Mean jitter values of patients with PLS and HSP were 26.5±12.1 µs and 30.8±34.8 µs, and the number of individual high jitters (>43 microseconds) observed in the PLS and HSP groups was 16/180 and 9/100, respectively without a significant intergroup difference. The ratio of patients with an abnormal jitter study were higher in HSP group (60%) compared to PLS (22%) (p<0.05). Potential pairs with blocking were present in HSP group (7 of 100 potential pairs) but not seen in PLS patients. EMS values were significantly lower in patients having potential pairs with high jitter and blocking compared to those without high jitter and blocking.

Conclusion: The present study has demonstrated that early signs of LMN dysfunction can be detected electrophysiologically by CN-jitter in patients with UMN involvement. These electrophysiological findings in these patients with longer disease duration and lower clinical scores may be explained by spreading of the disease to LMNs or transsynaptic degeneration and its contribution in disease progression.


SOURCE: Noro Psikiyatr Ars. 2019 Aug 16;57(3):228-233. doi: 10.29399/npa.23387. eCollection 2020 Sep. PMID: 32952426 Copyright: © 2020 Turkish Neuropsychiatric Society.

Electrophysiological Findings of Subclinical Lower Motor Neuron Involvement in Degenerative Upper Motor Neuron Diseases

Hava Özlem Dede  1 Nermin Görkem Şırın  1 Elif Kocasoy-Orhan  1 Halil Atilla Idrısoğlu  1 Mehmet Barış Baslo  1

  1. Department of Clinic Neurophysiology, İstanbul University İstanbul Faculty of Medicine, İstanbul, Turkey.


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