Upper motor neuron involvement in X-linked recessive bulbospinal muscular atrophy

C. Pachatz, C. Terracciano, M. T. Desiato, A. Orlacchio, F. Mori, C. Rocchi, G. Bernardi, R. Massa

Research output: Contribution to journalArticlepeer-review


Objective: Clinicopathological findings of X-linked recessive bulbospinal muscular atrophy (SBMA) are indicative of lower motor neuron and primary sensory neuron involvement. The aim of our study was to investigate the presence of subclinical upper motor neuron (UMN) dysfunction in this disease. Methods: Two siblings with clinical presentation, routine electrophysiological tests, histopathological features of muscle and nerve biopsies and genetic testing consistent with diagnosis of SBMA underwent transcranial magnetic stimulation (TMS). The analysed parameters were motor evoked potential (MEP) threshold, silent period (SP) and central motor conduction time. Intracortical inhibition with paired pulses from 1 to 6 ms interstimulus intervals (ISIs) was evaluated in the older brother. Results: MEP parameters were significantly altered in limb and cranial muscles and MEP suppression after paired stimulation significantly reduced in the older brother. MEP abnormalities were present in one lower limb, but SP abolished in all limbs, in the younger brother. Conclusions: Subclinical involvement of UMNs may be present in patients affected by SBMA. This finding suggests that the array of neuronal systems whose function may be affected by the pathogenic process of SBMA is larger than it was considered so far. Significance: TMS is a sensitive diagnostic tool for the identification of UMN dysfunction and should be included in the diagnostic evaluation of patients with SBMA.

Original languageEnglish
Pages (from-to)262-268
Number of pages7
JournalClinical Neurophysiology
Issue number2
Publication statusPublished - Feb 2007


  • Kennedy's disease
  • Muscle biopsy
  • Nerve biopsy
  • Transcranial magnetic stimulation
  • Upper motor neuron
  • X-linked recessive bulbospinal muscular atrophy

ASJC Scopus subject areas

  • Clinical Neurology
  • Radiology Nuclear Medicine and imaging
  • Neurology
  • Sensory Systems
  • Physiology (medical)


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