Brain Control of Movements in Cerebral Palsy
Condition: Cerebral Palsy
MeSH terms: Paralysis; Cerebral Palsy
Study type: Observational

Summary: 
      This study will examine how the brain controls movements in patients with certain types of
      cerebral palsy. In healthy people, one side of the body usually controls movements on the
      other side of the body. In patients with cerebral palsy, this pattern may be altered, and one
      side of the brain may control movements on the same side of the body. Information obtained
      from this study may lead to improved rehabilitation therapy strategies for patients with
      cerebral palsy.

      Healthy volunteers and patients with cerebral palsy between 6 and 18 years of age may be
      eligible for this study. All candidates will be screened with a medical history, physical
      examination, and psychological testing. In addition, patients with cerebral palsy will have
      hearing and vision tests, a review of their medical records, and a magnetic resonance imaging
      (MRI) scan if one has not been done within the past year. For this test, the patient lies on
      a table that slides into a narrow metal cylinder with a strong magnetic field (the scanner).
      The scanning time usually lasts between 45 and 90 minutes.

      Patients enrolled in the study also will be evaluated by a physiatrist and physical and
      occupational therapists. They will be examined for muscle stiffness and reflexes. Their gait
      and movements (e.g., how they pick up a glass of water) will be evaluated. They will be asked
      about their ability to perform activities around the house and at school and whether a
      wheelchair or walker is needed to get around. Patients may also be asked about how they are
      dealing with their movement problems and how it affects their caregivers.

      All participants will undergo three tests, described below, to evaluate movement control. The
      first two tests use electrodes (small metal discs) taped to the skin over the muscles in both
      hands to measure muscle activity. A small disc placed on the fingers detects and measures the
      hand movements. The third test uses magnetic pulses that stimulate the brain to study how the
      brain controls movements.

        1. Quantitative test of fine motor function: For this test, the subject taps buttons at
           different speeds on a box attached to a computer. The test is similar to playing simple
           computer games.

        2. Long latency reflexes: For this test, the subject's hand is lightly strapped into a
           holder that holds the hand still while a motor moves the index finger with sudden small
           movements. These reflexes may also be tested using a gentle shock to the finger
           delivered through a ring electrode.

        3. Transcranial magnetic stimulation: For this test, the subject sits in a comfortable
           chair. An insulated coil is held on the scalp. A magnetic pulse from the coil stimulates
           the brain. The subject may hear a click and feel a snap or pulling sensation on the
           scalp under the coil. The stimulation may also cause twitching in the muscles of the arm
           or leg. During the stimulation, the subject may be asked to move certain muscles or
           perform other simple actions.
    

Detailed description: 
      Although the capacity of the immature nervous system to recover after injury is superior to
      that of the adult brain, children with cerebral palsy carry a great burden of morbidity for
      their entire life. Functional outcome may be determined not only by characteristics of the
      lesion (size, location, and timing) but also by the response of the brain to the lesion
      (cortical re-organization). Little is known about how underlying limitations, such as
      inefficient cortical re-organization, affect functional outcome and response to therapy in
      children with cerebral palsy. Because of this, individual rehabilitation strategies are based
      solely on the level of functioning rather than on the underlying impairment. Research
      demonstrates that novel rehabilitation strategies can manipulate plasticity of the motor
      cortex and, in this way, improve functional outcome in adults who have suffered a stroke.
      There is preliminary evidence that these treatments may also benefit patients with cerebral
      palsy. However, cortical re-organization after an injury to the developing brain may not be
      similar to that which occurs after a stroke in the adult brain. It would be of benefit to
      have a greater understanding of the impairments that arise from inefficient cortical
      re-organization in children with cerebral palsy. It is also important to have the research
      methodology to assess the effect of these novel treatments in order to measure their true
      benefit.

      Cortical re-organization can lead to enhanced participation of the unaffected hemisphere via
      anomalous ipsilateral corticofugal motor projections. Recent evidence suggests that this form
      of neural re-organization may not be efficient. Three different types of ipsilateral
      projections are thought to exist: 1) fast-conducting developmental ipsilateral projections
      that persist beyond the age at which they normally disappear; 2) slow-conducting ipsilateral
      tracts present in healthy subjects that become more accessible after injury; 3)
      fast-conducting projections that arise de novo from the ipsilateral primary motor cortex
      after injury to the developing brain. Each type has a distinct neurophysiologic profile that
      can be characterized using transcranial magnetic stimulation (TMS) and electromyography
      (EMG).

      To date, the relationship between anomalous ipsilateral corticofugal motor projections and
      functional outcome has not been examined in detail. There is preliminary evidence that the
      presence of these anomalous ipsilateral projections is associated with poor outcome,
      suggesting that they represent an inefficient cortical re-organization process. In addition,
      the anomalous projections that arise de novo from the ipsilateral primary motor cortex appear
      to have the worst prognosis. The proposed research study will characterize anomalous
      ipsilateral corticofugal motor projections in a group of children with spastic hemiplegia and
      spastic diplegia subtypes of cerebral palsy using TMS and EMG. We will evaluate functional
      limitations of the hand in these children and will examine the relationship between each type
      of ipsilateral pathway and functional outcome. In this way, it will be possible to determine
      which anomalous ipsilateral projections are associated with poor function in patients with
      cerebral palsy.

      This study will increase our understanding of the functional significance of these
      ipsilateral projections and will make it possible to identify these ipsilateral projections
      in individual children. The neurophysiologic techniques developed in this study will provide
      essential research methodology to assess brain re-organization before and after novel
      therapeutic approaches.
    

Keywords: Corticospinal Tracts; Spastic Hemiplegia; Spastic Diplegia; Cortical Re-Organization; Functional Outcome; Cerebral Palsy