Letter to the Editor: Early noninvasive brain stimulation after severe TBI

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TO THE EDITOR: We read with interest the review by Shin et al.7 (Shin SS, Dixon CE, Okonkwo DO, et al: Neurostimulation for traumatic brain injury. J Neurosurg 121:1219–1231, November 2014), which addressed the potential of noninvasive stimulation for treating posttraumatic cognitive impairment, but also pointed out the possible risk of functional impairment depends on the stimulation site and parameters.

One of the most prevalent neuropsychiatric outcomes of traumatic brain injury (TBI), particularly severe TBI, is personality change.5,6 These changes, as reported by Tate et al. (1999), can more precisely be defined as behavioral manifestations of cognitive deficits acquired after the TBI.8 Most likely, this intimate relationship between cognitive deficits and personality changes explains the latter as a highly independent factor that is associated with not returning to work in survivors of severe TBI.4

Noninvasive cerebral stimulation is a promising intervention for the treatment of cognitive impairment after TBI.1 According to Villamar et al.,9 the acute recovery of cerebral functions after brain injury includes the activation of cellular repairs, which occurs in the earlier weeks following injury, cellular plasticity, and anatomical plasticity, including the formation of new connections. After the acute phase, remyelization and plasticity are the main processes that occur—particularly during the 3 months following the trauma. Certain methods of cerebral stimulation are able to suppress some of the pathological events and to reinforce other favorable processes, inducing cognitive and motor function recovery, which in turn help to minimize incapacitating sequelae.9 Accordingly, the theoretical use of adequate noninvasive cerebral stimulation early after TBI could result in a neuroprotective action that may help to reduce the incidence and severity of long-term neuropsychiatric complications of TBI. Nevertheless, the risks of transcranial magnetic stimulation (TMS)-induced seizures and skull conductance modifications, for example, especially in severe TBI victims, could limit the use of such interventions in the period immediately after the trauma; indeed, the potential for neuropsychological damage may even be intensified with their application.1 Still, the identification of biomarkers with sufficient accuracy to discriminate among those individuals with a higher chance of a worse prognosis could help to evaluate a risk/benefit relationship linked to early interventions, such as noninvasive cerebral stimulation.

In a recent study, we demonstrated that the duration of posttraumatic amnesia (PTA) was independently associated with personality changes, a clinical entity that is deeply connected with global cognitive deficits.3 An important limitation of that study, the retrospective evaluation of PTA, could be eliminated with prospective data collection, permitting the identification of the cutoff for the risk of personality changes as well as predicting specific cognitive deficits that are associated with both behavioral disorders and impaired activities of daily living, including the ability to return to work. These issues are being investigated by an ongoing multicenter study.

Noninvasive cerebral stimulation for enhancing cognition in neuropsychiatric disorders is undoubtedly a promising method.2 Compared to other brain diseases, such as Alzheimer’s disease, schizophrenia, autism spectrum disorders, and attention deficit hyperactivity disorder, TBI has the benefit of the exact time of onset of the pathophysiological process being known. This advantage facilitates the completion of studies using noninvasive techniques as a neuroprotective method for individuals with higher risks of cognitive sequelae.

The possibility of mitigating the cognitive deficits associated with TBI using noninvasive brain stimulation in an early phase after trauma based on the duration of PTA in higher-risk individuals could have a positive impact on reducing the social burden associated with TBI. In particular, this treatment strategy could minimize the personal and familial suffering that accompanies severe TBI for a significant portion of survivors.

References

  • 1

    Demirtas-Tatlidede AVahabzadeh-Hagh AMBernabeu MTormos JMPascual-Leone A: Noninvasive brain stimulation in traumatic brain injury. J Head Trauma Rehabil 27:2742922012

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  • 2

    Demirtas-Tatlidede AVahabzadeh-Hagh AMPascual-Leone A: Can noninvasive brain stimulation enhance cognition in neuropsychiatric disorders?. Neuropharmacology 64:5665782013

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  • 3

    Diaz APSchwarzbold MLGuarnieri Rde Oliveira Thais MEHohl ANunes JC: Posttraumatic amnesia and personality changes after severe traumatic brain injury: preliminary findings. CNS Neurosci Ther 20:4794822014

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  • 4

    Diaz APSchwarzbold MLThais MECavallazzi GGSchmoeller RNunes JC: Personality changes and return to work after severe traumatic brain injury: a prospective study. Rev Bras Psiquiatr 36:2132192014

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  • 5

    Diaz APSchwarzbold MLThais MEHohl AMore MSchmoeller R: Psychiatric disorders and health-related quality of life after severe traumatic brain injury: a prospective study. J Neurotrauma 29:102910372012

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  • 6

    Rao VSpiro JRHandel SOnyike CU: Clinical correlates of personality changes associated with traumatic brain injury. J Neuropsychiatry Clin Neurosci 20:1181192008. (Letter)

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  • 7

    Shin SSDixon CEOkonkwo DORichardson RM: Neurostimulation for traumatic brain injury. J Neurosurg 121:121912312014

  • 8

    Tate RL: Executive dysfunction and characterological changes after traumatic brain injury: two sides of the same coin?. Cortex 35:39551999

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  • 9

    Villamar MFSantos Portilla AFregni FZafonte R: Noninvasive brain stimulation to modulate neuroplasticity in traumatic brain injury. Neuromodulation 15:3263382012

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Response

We appreciate the interest of Diaz et al. in our recent review of brain stimulation strategies for the treatment of TBI. These authors specifically comment on the potential use of noninvasive brain stimulation in the more acute period following TBI. They suggest that the duration of PTA is a potential criterion for the use of brain stimulation because it can possibly identify those individuals at most risk for post-TBI personality changes. This is an interesting idea, and it highlights the complexity of TBI and the difficulty inherent in selecting appropriate patients and time frames after injury in which to initiate experimental therapies. Clearly, no single parameter will be sufficient for this purpose. The identification of structural imaging, functional imaging, and electrophysiological biomarkers that, in combination with clinical characteristics such as PTA, may predict the potential for therapeutic modulation by neurostimulation, remains a primary goal for research in this field.

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Article Information

INCLUDE WHEN CITING Published online June 5, 2015; DOI: 10.3171/2014.12.JNS142425.

DISCLOSURE The authors report no conflict of interest.

© AANS, except where prohibited by US copyright law.

Headings

References

  • 1

    Demirtas-Tatlidede AVahabzadeh-Hagh AMBernabeu MTormos JMPascual-Leone A: Noninvasive brain stimulation in traumatic brain injury. J Head Trauma Rehabil 27:2742922012

    • Search Google Scholar
    • Export Citation
  • 2

    Demirtas-Tatlidede AVahabzadeh-Hagh AMPascual-Leone A: Can noninvasive brain stimulation enhance cognition in neuropsychiatric disorders?. Neuropharmacology 64:5665782013

    • Search Google Scholar
    • Export Citation
  • 3

    Diaz APSchwarzbold MLGuarnieri Rde Oliveira Thais MEHohl ANunes JC: Posttraumatic amnesia and personality changes after severe traumatic brain injury: preliminary findings. CNS Neurosci Ther 20:4794822014

    • Search Google Scholar
    • Export Citation
  • 4

    Diaz APSchwarzbold MLThais MECavallazzi GGSchmoeller RNunes JC: Personality changes and return to work after severe traumatic brain injury: a prospective study. Rev Bras Psiquiatr 36:2132192014

    • Search Google Scholar
    • Export Citation
  • 5

    Diaz APSchwarzbold MLThais MEHohl AMore MSchmoeller R: Psychiatric disorders and health-related quality of life after severe traumatic brain injury: a prospective study. J Neurotrauma 29:102910372012

    • Search Google Scholar
    • Export Citation
  • 6

    Rao VSpiro JRHandel SOnyike CU: Clinical correlates of personality changes associated with traumatic brain injury. J Neuropsychiatry Clin Neurosci 20:1181192008. (Letter)

    • Search Google Scholar
    • Export Citation
  • 7

    Shin SSDixon CEOkonkwo DORichardson RM: Neurostimulation for traumatic brain injury. J Neurosurg 121:121912312014

  • 8

    Tate RL: Executive dysfunction and characterological changes after traumatic brain injury: two sides of the same coin?. Cortex 35:39551999

    • Search Google Scholar
    • Export Citation
  • 9

    Villamar MFSantos Portilla AFregni FZafonte R: Noninvasive brain stimulation to modulate neuroplasticity in traumatic brain injury. Neuromodulation 15:3263382012

    • Search Google Scholar
    • Export Citation

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