Biomedical Engineering Reference
In-Depth Information
and classification methods for BCIs, and the results are published in peer-reviewed
journals. Many researchers have taken up this challenge (Sajda et al. 2003; Blankertz et al.
2004, 2006).
A key point in using BCIs with LIS patients is their usefulness as a cognitive rehabilitation
device. At the present moment, CLIS patients are not able to communicate with BCI
devices (Kübler and Birbaumer 2008). In 2007, one study reported 17 CLIS patients trained
with a NIRS-based BCI (Naito et al. 2007). Questions requiring simple “yes” and “no”
answers were presented to the patients. The “yes” answer was associated with an increase
in the blood oxygenation of the patients, whereas the “no” answer was associated with
a decrease. Seven patients achieved 70% correctness, although the study suffered from
a lack of quantification and definition of the clinical criteria used for the CLIS patients
(Birbaumer et al. 2009).
It has been frequently proposed that LIS patients lack communication because of the
progression of the disease (Sellers and Donchin 2006). Birbaumer (2006) and Kübler and
Birbaumer (2008) explained that in long-term paralyzed patients, intentional thoughts
are rarely followed by rewarding or punishing stimuli, causing a decrease of causal
contingency perception between the thought and its consequences, which progressively
extinguishes in the complete locked-in state. Extensive use of a BCI beginning before the
locked-in state may potentially help in providing the rewarding stimuli necessary for
causal attribution, supposedly preventing a complete lack of communication.
17.5 Motor Restoration
17.5.1 Potential Users
Severe injuries of the motor system, such as a stroke or traumatic brain or spinal cord
injury, may lead to paralysis or semiparalysis of the limbs. Depending on the severity
and location of the injury, these diseases can cause breathing difficulties, numbness, and
sensory changes as well as severe weakness or paralysis of the limbs. When injuries occur
at the chest level of the spinal cord, there can be a condition called paraplegia, impairing
motor and/or sensory functions of the lower limbs. When the injury occurs at the neck
level of the spinal cord, impairment can occur at the upper and lower limbs, and injuries
at the trunk level can cause breathing problems. This condition is known as tetraplegia or
quadriplegia.
It has been reported that in 2005, in the United States, approximately 250,000 persons
were surviving a spinal cord injury (Wyndaele and Wyndaele 2006). It has also been
estimated that the annual incidence in the United States of spinal cord injuries is
approximately 11,000 new cases each year, not considering people who do not survive the
accident. Stroke is also a major concern for public health. Approximately 750,000 strokes
occur each year in the United States (Carandang et al. 2006). In the United Kingdom,
approximately 50% of stroke survivors are left dependent on other people for everyday
activities (Rothwell et al. 2004), whereas in Germany one-third of the patients that survive
the first year present with hemiplegia (Millán et al. 2010). Nearly one-third of stroke
patients are not able to use the paralyzed limb one year after the injury (Lai et al. 2002),
and no effective treatment is available (Birbaumer et al. 2008; Buch et al. 2008), causing a
considerable negative impact on the patients, their families, and the society.
