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• Re:Transcranial magnetic stimulation is a useful diagnostic test in psychogenic paralysis
  Ruth Geraldes
  Published on: 26 April 2010
• Transcranial magnetic stimulation is a useful diagnostic test in psychogenic paralysis
  Carlo Civardi
  Published on: 4 January 2010

• Published on: 26 April 2010

  Re:Transcranial magnetic stimulation is a useful diagnostic test in psychogenic paralysis

  • Ruth Geraldes, Neurologist
  • Other Contributors:
    • Professor Mamede de Carvalho

  I thank Dr. Civardi and his group, who have demonstrated a large experience with the practical use of Motor Evoked Potentials, for their interest in our article describing a patient with presumed psychogenic left hemiparalysis and abnormal transcranial magnetic stimulation (TMS) (1). Our initial aim in performing TMS to our patient was exactly to prove that MEPs were normal, as suggested by other authors (including Dr. C...

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  I thank Dr. Civardi and his group, who have demonstrated a large experience with the practical use of Motor Evoked Potentials, for their interest in our article describing a patient with presumed psychogenic left hemiparalysis and abnormal transcranial magnetic stimulation (TMS) (1). Our initial aim in performing TMS to our patient was exactly to prove that MEPs were normal, as suggested by other authors (including Dr. Civardi and coworkers). However, in our patient, there was a non- significant difference between left and right hemisphere MEP amplitudes, but the cortico-motor threshold was 170% higher in the right hemisphere. The similar F-waves size between sides excluded a difference in lower motor neuron excitability. These changes reverted after the patient has recovered and the diagnosis of conversive disorder has been explained. Dr. Civardi refers to an important retrospective study on TMS in psychogenic paralysis, since it shows that normal TMS can reassure the neurologist regarding the absence of a structural CNS dysfunction (2). In this work a single evaluation was made in 21 patients, 15 of which had a unilateral/asymmetric paralysis. From this group only 9 patients had the final diagnosis of conversive disorder. Although Dr. Civardi states, in his letter, that no differences between hemispheres were found, this is not reported in the referred paper (only mean values are shown). By the time of our report, only a few papers addressed changes on MEPs related to immobilization and reports on voluntary inhibition of movement mainly analysed the ability to inhibit prepared movements and did not specifically analysed MEP thresholds (3,4). As previously stated, conclusions from a single case should be cautious; especially when we now know that cognitive processes such as motor imagering may influence the results (5). Studies making comparisons between normal controls and patients with conversive paresis should clearly state controls test conditions (was there an indication to be quiet, to think of movement and inhibiting it, etc), otherwise subtle differences may be neglected. We recently had another patient with conversive hemiparesis in whom the affected hemisphere showed a strikingly increased cortico-motor threshold in the involved hemisphere. This fact may be conflicting with the existing literature, however it fits with the functional imaging data, and should be further investigated, namely with well defined task protocols.

  1. Geraldes R, Coelho M, Rosa MM, Severino L, Castro J, de Carvalho M. Abnormal transcranial magnetic stimulation in a patient with presumed psychogenic paralysis. JNNP; 2008; 79:1412-1413 2. Cantello R, Boccagni C, Civardi C, Monaco F. Diagnosis of psychogenic paralysis: the role of motor evoked potentials. J Neurol; 2001; 248:889- 897 3. Crews RT, Kamen G. Motor-evoked potentials following imagery and limb disuse. Int J Neurosci.2006;116(5):639-513. 4. Cocon JP, Stinear CM, Byblow WD. Intracortical inhibition during volitional inhibition of prepared action. J Neurophysiol. 2006; 95(6):3371 -83 5. Liepert J, Hassa T, Tuscher O, Schmidt R. Abnormal motor excitability in patients with psychogenic paresis. A TMS study. J Neurol. 2009; 256(1):121-6.

  Conflict of Interest:

  None declared

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  Conflict of Interest:
  None declared.

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• Published on: 4 January 2010

  Transcranial magnetic stimulation is a useful diagnostic test in psychogenic paralysis

  • Carlo Civardi, neurologist
  • Other Contributors:
    • Alessandra Collini, Francesco Monaco

  Dear Editor,

  I read with interest the article by Geraldes et al.[1] on the use of transcranial magnetic stimulation (TMS) in psychogenic paralysis. The Authors showed in a young lady with a reversible left body limbs paresis due to conversion disorders (CD), a significant increase of corticomotor threshold and reduction in amplitude of motor evoked potentials (MEP) in the affected side. These changes were resto...

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  Dear Editor,

  I read with interest the article by Geraldes et al.[1] on the use of transcranial magnetic stimulation (TMS) in psychogenic paralysis. The Authors showed in a young lady with a reversible left body limbs paresis due to conversion disorders (CD), a significant increase of corticomotor threshold and reduction in amplitude of motor evoked potentials (MEP) in the affected side. These changes were restored with the normalization of clinical pictures. Geraldes et al. concluded that neurophysiological changes were due to brain modulation proper of CD moreover they affirm that in no previous study corticomotor threshold was investigated. In a previous TMS-psychogenic palsy larger (21 patients) study [2] corticomotor threshold and MEP amplitude were explored without any significant differences respect to the unaffected side nor to the controls group. CD frequently represents a great challenge for neurologist and TMS contribute to speed up this diagnosis in psychogenic paralysis [2]. Although the hypothesis of Geraldes et al. may be intriguing, their TMS findings could confuse the already complex diagnostic pathway in patients with psychogenic paralysis.

  Geraldes R, Coelho M, Rosa MM, Severino L, Castro J, de Carvalho M. Abnormal transcranial magnetic stimulation in a patient with presumed psychogenic paralysis.J Neurol Neurosurg Psychiatry. 2008 ;79(12):1412- 1413.

  Cantello R, Boccagni C, Comi C, Civardi C, Monaco F. Diagnosis of psychogenic paralysis: the role of motor evoked potentials. J Neurol. 2001 ;248: 889-897.

  Conflict of Interest:

  None declared

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  Conflict of Interest:
  None declared.

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