title: Abnormal corticospinal excitability in patients with disorders of consciousness.
abstract: BACKGROUND
  Transcranial magnetic stimulation (TMS) has been frequently used to explore changes in the human motor cortex in different conditions, while the extent of motor cortex reorganization in patients in vegetative state (VS) (now known as unresponsive wakefulness syndrome, UWS) and minimally conscious (MCS) states due to severe brain damage remains largely unknown.
  
  
  OBJECTIVE
  It was hypothesized that cortical motor excitability would be decreased and would correlate to the level of consciousness in patients with disorders of consciousness.
  
  
  METHODS
  Corticospinal excitability was assessed in 47 patients (24 VS/UWS and 23 MCS) and 14 healthy controls. The test parameters included maximal peak-to-peak M-wave (Mmax), F-wave persistence, peripheral and central motor conduction times, sensory (SEP) and motor evoked (MEP) potential latencies and amplitudes, resting motor threshold (RMT), stimulus/response curves, and short latency afferent inhibition (SAI). TMS measurements were correlated to the level of consciousness (assessed using the Coma Recovery Scale-Revised).
  
  
  RESULTS
  On average, the patient group had lower Mmax, lower MEP and SEP amplitudes, higher RMTs, narrower stimulus/response curves, and reduced SAI compared to the healthy controls (P < 0.05). The SAI alterations were correlated to the level of consciousness (P < 0.05).
  
  
  CONCLUSIONS
  The findings demonstrated the impairment of the cortical inhibitory circuits in patients with disorders of consciousness. Moreover, the significant relationship was found between cortical inhibition and clinical consciousness dysfunction.
authors: Research Department, Hammel Neurorehabilitation and Research Centre, Voldbyvej 15, 8450 Hammel, Denmark. natlap@rm.dk
authors: Natallia
authors: N
authors: Lapitskaya
authors: Olivia
authors: O
authors: Gosseries
authors: Victor
authors: V
authors: De Pasqua
authors: Asger Roer
authors: AR
authors: Pedersen
authors: Joergen Feldbaek
authors: JF
authors: Nielsen
authors: Alain Maertens
authors: AM
authors: de Noordhout
authors: Steven
authors: S
authors: Laureys
mesh_terms: D000328:Adult; D000368:Aged; D003244:Consciousness Disorders / Q000503:physiopathology*; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005073:Evoked Potentials, Somatosensory / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000503:physiopathology; D009433:Neural Inhibition / Q000502:physiology; D011446:Prospective Studies; D011712:Pyramidal Tracts / Q000503:physiopathology*; D050781:Transcranial Magnetic Stimulation
keywords: Brain injury; Minimally conscious state; Motor evoked potentials; Short latency afferent inhibition; Somatosensory evoked potentials; Transcranial magnetic stimulation; Unresponsive wakefulness syndrome; Vegetative state