This document provides an overview of biofeedback as a technique used in neurological rehabilitation. It defines biofeedback as using electronic devices to help patients learn how to change physiological functions to improve health. Specific types of biofeedback discussed include electromyography (EMG) biofeedback to train muscle control, joint angle biofeedback to improve joint movement, and force/pressure biofeedback for retraining balance. The document also covers biofeedback modalities, equipment, and applications in treating conditions like stroke and abnormal gait patterns.

1. BIOFEEDBACK IN
NEUROLOGICAL
REHABILITATION
PRESENTED BY
ARFA SULTANA MOHAMMED,
MPT 1ST YEAR,NEUROLOGY,
VAPMS COLLEGE OF PHYSIOTHERAPY.

2. WHAT IS NEUROREHABILITATION?
◦ Neurological rehabilitation - so called neurorehabilitation is a
special field of rehabilitation that requires highly-qualified
specialist personnel and use of complex methods enabling
the treatment of physical, cognitive, behavioural and social
deficits diagnosed in patients with neurological problems.
◦ Neurorehabilitation was defined as a set of methods that aim
at restoration of lost or improper neurological functions.
◦ It is used in case of injuries or diseases within cerebrum or
spinal cord.

3. ◦ Neurorehabilitation methods use the phenomenon of brain plasticity
in order to improve or normalise the neurological or functional
deficits.
◦ One should remember that neurorehabilitation is often treated as a
separate process performed only in a given organizational unit ,
constituting an important and integral part of therapeutic procedure
that should be applied for patients with neurological diseases.
◦ Application of basic rules used in rehabilitation, i.e. reliable and
complex assessment of patient, determination of goals and
performance of proper therapy methods, the disordered functions can
be optimised with simultaneous prevention of other complications
and minimisation of excessive stress both for the patient and his/her
family.

4. ◦ The more and more numerous scientific reports indicate the fact
that properly constructed therapeutic programs may improve the
treatment results in case of many neurological problems in the field
of neurorehabilitation, also the cognitive one.
◦ Therefore, so called traditional model of procedure is often
“enriched” with new therapeutic methods or improved rehabilitation
equipment.
◦ All these modifications aim at the faster recovery of patient or full
use of his/her widely understood functioning potential.
◦ One of the techniques that is often introduced to neurorehabilitation
is the biofeedback method.

5. WHAT IS BIOFEEDBACK?
◦ Biofeedback is a technique that uses electronic devices,
which enables the unit to learn how to change the
physiological function of organism in order to improve health
and efficiency/effectiveness of a given function of organism.
◦ Biofeedback is also defined as a method of body-mind
training that helps patients with achievement of awareness
and control of physiological processes such as: breathing,
pulse, muscle tone, skin temperature, electrodermal reaction,
blood pressure or hemoencephalographic record.

6. ◦ Biofeedback (BF) can be defined as the use of instrumentation
to reveal covert physiological processes via user detectable
cues, such as visible light and audible tone, for appropriate
response shaping.
◦ The BF loop consists of a BF machine and user, and as
necessary an instructor/trainer/clinician.
◦ Ultimately, the machine functions as an extension of human
sense to record and display the internal physiological signals or
events; the user, armed with feedback information, acquires the
skills to control the physiological response toward desired state
through mind-body self-regulation.

7. ◦ Biofeedback became recognized as an alternative or adjunct
medical tool in the 1960s and has been applied to
psychotherapy, physical medicine, sports medicine, incontinence
treatment, pain management, and more recently, in the
management of other behaviors associated with pediatrics and
oncology.
◦ From the 1960s to the 1990s, most clini-cal and experimental BF
applications used EMG, joint angle, position, force, or pressure
to reeducate the control of muscles, joint, and balance in
patients with various neuromotor deficits.

8. ◦ The outcomes provided concrete evidence that objective
neurological signs and symptoms can be altered, particularly in
patients with upper motor neuron paralysis and spasticity resulting
from brain damage.
◦ Since the mid-1990s, several experimental studies, inspired by the
concept of task-oriented training for motor functional recovery, have
transformed BF interventions into functional task training that might
employ feedback principles. In addition, recent technological
advances have further promoted this new direction.
◦ The emergence of novel sensors, advanced signal processing and
control, remote communication, and three-dimensional (3D) displays
in BF applications will further leverage the influence of BF therapy in
physical medicine and rehabilitation.

9. ◦ ELECTROMYOGRAPHIC BIOFEEDBACK :
◦ The electromyographic signal or EMG is an electrical
manifestation of muscle activity and an effective window to
inspect neuromuscular control system.
◦ In BF retraining, EMG is the most used form to down-train
hyperactive muscles or up-train flaccid or weak muscles in
patients with various sensorimotor deficits, thus further
improving patients’ control over joint.
METHODS OF BIOFEEDBACK

10. ◦ Usually, bipolar surface EMG electrodes are placed on one or
two targeted muscles.
◦ The sensed signals are digitally sampled at 1,000 Hz or higher
rate.
◦ The raw signal, the integrated EMG, or the frequency of EMG is
then translated into simple acoustic and visual signals (e.g.,
lights and audio cues) or graphic computer displays.
◦ Patients receive the feedback in a quiet environment and mostly
in a static posture.
◦ Noise is held to a minimum, and visual distractions avoided.

11. Basic block diagram of an electromyographic biofeedback device.
LED, light-emitting diode.

13. ◦ Special uses of intramuscular EMG (IMG) BF include attempts at
training deep inaccessible muscles, paralytic muscles, muscles
separated from the skin by considerable adipose tissue, or muscles
that are not easily isolated by surface electrodes.
◦ IMG signals are commonly recorded by invasive, indwelling fine-wire
or concentric needles and sampled at 10 kHz or higher rate.
JOINT ANGLE BIOFEEDBACK :
◦ Joint angle BF can be efficient for improving joint movement control ,
even more than EMGBF( electro-myo-graphic biofeedback).

14. ◦ When the active joint motion is presented but limited in patients
with neuro-motor deficits, compared to EMGBF, joint angle BF
might be promising for effective and expeditious recovery of joint
control.
◦ In addition, angle BF is indicated when the goal of training is the
regulation of joint movement, such as correction of genu
recurvatum or the control of movement with appropriate timing
and coordination.
◦ Moreover, joint angle BF may be used when the muscle that must
be monitored is inaccessible or difficult to isolate.

15. ◦ Electro-goniometers reliably reproduced the clinical measurements
of joint angle they have been widely employed in angle BF
devices. Other applied sensors include mercury tilt switches and
gyroscopes.
◦ The quantified joint angle is fed back to the patient during single
joint movement for targeted angle tracking, or during multijoint
coordinated movement, such as gait.
PRESSURE OR FORCE BIOFEEDBACK :
◦ Force or pressure monitoring may be indicated when information
concerning the amount of force being transmitted through a body
segment or assistive device is desired.

17. ◦ Force/pressure sensitive platforms whose applications are often used
for retraining of balance.
◦ As shown in Figure 70-2, a patient with balance control deficits stands
on a force plate that measures the ground reaction force or pressure
and/or moments in three orthogonal directions under the feet.
◦ The derivative of force or pressure measurements such as center of
force (COF), center of pressure (COP), or center of gravity (COG) is
displayed as a cursor projected on a two-dimensional (2D) screen in
front of patients.
◦ The goal of the patients is to move the cursor to a desired location or
within a targeted area.
◦ Some commercial force platforms are also equipped with motors that
can translate or tilt the platform for balance perturbation.

18. ◦ Force BF training under conditions of posture perturbation have
been applied to permit older adults at risk of fall to experience
strategies to abort falls.
MISCELLANEOUS TECHNIQUES :
◦ Beyond EMG, joint angle, and force, many other parameters
have been monitored for miscellaneous BF applications in
neuromotor rehabilitation.
◦ For example, BF of step length, knee-to-knee distance, and step
timing were applied to correct abnormal gait pattern.
◦ Trunk acceleration was the BF parameter for stance balance
training.

19. ◦ The applied BF equipment ranged from a simple mirror to
expensive motion tracking cameras.
◦ Some studies conducted BF training using multiple data
sources.
◦ For example, studies coupled EMGBF with joint angle BF and
trained stroke patients to control the joint to a desired position
by increasing the recruitment of agonist and/or reducing the
muscle activity from antagonist.
◦ The risk in using multisource BF is that multiple quantified
feedback cues might overload patients’ perception and confuse
patients; careful design of feedback cue displays is essential for
successful BF applications.

20. BIOFEEDBACK MODALITIES
VISUAL FEEDBACK :
◦ Visual displays available with BF devices include banks of
lights, liquid crystal display (LCD), meters, oscilloscopes, or
computer monitors.
◦ The visual display can be binary (0/1 in value or light on/off),
digital (integral numbers), or continuous (signal waves or value
bar).
◦ The sensitivity scale in the visual display should be determined
by the goals for the BF training.

21. ◦ Most contemporary feedback displays have software that
adjusts the range of sensitivities as the patient changes his or
her muscle output capability with an intent of providing a
continuous range that can be visualized and manipulated by the
patient within his or her training sessions.
◦ Caution must be exercised when trainees have visual deficits
secondary to brain injury.
◦ Furthermore, when the BF training involves activities such as
gait, visual feedback should be avoided or kept minimal because
vision is largely occupied to guide motor coordination.

23. AUDIO FEEDBACK :
◦ Many commercially available devices offer auditory feedback in the
form of a tone, buzzer, click, or a combination of these possibilities.
◦ Similar to visual feedback, the audible feedback could be binary,
discrete, or continuous. In devices with binary display, a monotone
buzzer is heard only when the patient achieves a specific feedback
value preset by the therapist.
◦ In EMGBF, a low threshold setting may be used in training for
recruitment of activity above a given level in a weak or paretic
muscle. Once the patient reliably exceeds this level, the thresh-old
is raised progressively. This technique is often referred to as
shaping.

24. ◦ The reverse shaping strategy to reduce integrated EMG levels
(i.e., reduction of resting hypertonus) also may be used.
◦ Additionally, binary auditory feedback is useful for BF therapy set
in the activities of daily living (ADL); the auditory tone is given only
if needed so that users can concentrate on the daily activities
most of the time.
◦ The device with discrete audible feedback maps more than two
physiological states into sounds with different pitch, duration, or
loudness. The continuous auditory feedback directly displays the
sampled physiological signal.
◦ For example, surface EMG was directly transformed into a sound.

27. ◦ When the muscle is activated, the audio components increase in
intensity and pitch, which can be resolved by patients as effective
feedback required to regulate the muscle activation level.
Tactile Feedback :
◦ Applied tactile sensation arises from a simple mechanical
vibrating stimulator attached to the skin.
◦ By modulating the vibration frequency and amplitude, the
vibrating stimulator feeds back the sensed physiological signal to
the user.
◦ Vibrotactile feedback is safe, frees the user from having to
maintain visual attention to the feedback cues, and presents
minimum distraction to others.

28. TACTILE BIOFEEDBACK

29. SCIENTIFIC BASIS OF
BIOFEEDBACK
◦ The mechanisms underlying successful use of BF are still
unclear. In physical rehabilitation, BF may enhance
sensorimotor integration because this approach highlights
utilization of sensory cues that inform patients about
consequences of their movements while allowing them to
develop adaptive strategies for motor learning and recovery.
Neurological Basis of Biofeedback :
◦ Previous studies demonstrated that the BF therapy was
associated with cortical reorganization.

30. ◦ Specifically, fMRI studies have shown that following biofeedback
training to enhance ambulation following stroke, enhanced
activation during controlled knee flexion extension was seen in
the ipsilesional primary sensorimotor cortex.
◦ Nonetheless, the central nervous system uses a multitude of
internal modulatory networks.
◦ The role of somatosensory or other subcortical areas, and the
basal ganglia should not be underemphasized; their timely
activation make voluntary movements meaningful.
◦ Proprioception, tactile, auditory, and visual inputs are harmonized
into the controls, as is the cerebellum.

31. ◦ Therefore, damage resulting from external and internal trauma to
area 4 of the cerebral cortex may spare pathways that are primarily
engaged for reacquisition of skilled move-ments, or they may spare
redundant pathways that EMGBF training can bring into play.
◦ Three detailed conceptualizations:
(a)Override: visual or audio feedback may activate the
somatosensory cortex by entering at a level higher than the level of
damage;
(b)Bypass: an appropriate feed forward system can be established
via the brain stem motor nuclei;
(c)Repetition with existing neural circuitry: central synapses
previously unused in executing motor commands may be activated
by visual and audio feedback.

32. BIOFEEDBACK
APPLICATION IN
PHYSICAL MEDICINE
AND REHABILITATION

33. STROKE REHABILITATION :
◦ A major application of biofeedback in rehabilitation hospitals and
outpatient clinics lies in the treatment of patients following stroke.
◦ The National Institute for Health lists stroke as the number one
cause of adult disability in the United States.
◦ Approximately 780,000 people experience a new or recurrent
stroke each year.
◦ Motor dysfunction after stroke may be characterized by muscle
weakness, abnormal muscle tone, abnormal movement
synergies, and lack of coordination during voluntary movement.

34. ◦ Restoring the neuromuscular control in patients with stroke is
essential to further improve their motor functions. EMGBF is a
useful tool for reeducating neuromuscular control in stroke
rehabilitation.
◦ Other forms of BF, such as force and joint angle BF, have also been
applied, but with less frequent use.
EMG Biofeedback for Upper- and Lower-Extremity Rehabilitation :
◦ The presence of proprioceptive loss appeared to diminish the
probability of making functional gains in the upper limb.
◦ Age, gender, hemiparetic side, duration of stroke, previous reha-
bilitation, and number of training sessions did not have a significant
effect.

35. ◦ Scientists at Emory University have conducted a series of studies
to implement EMGBF for stroke rehabilitation. The belief that
neurological patients should first have hyperactive muscle down-
trained motivated the application of EMGBF to spastic muscles
initially.
◦ Relaxation training was applied on patients when they were at
rest, during passive movements, during distractive movements,
and then during shortening contractions.
◦ Once the muscles were relaxed, attention was directed toward
the antagonist muscles, the ones that are usually weak and need
to be up-trained in EMGBF.
◦ Last, the coordination of both muscle groups must be trained for
efficient joint control.

36. ◦ Ultimately, this BF training paradigm was put into a functional
context. While this paradigm did yield significant improvements, the
greatest predictor for ultimate success in applying EMGBF was in
the patients’ abilities to demonstrate small amounts of active
extension at the elbow, wrist, and fingers.
◦ EMGBF for upper-extremity rehabilitation starts from the shoulder
joint, followed by elbow, wrist, and hand.
◦ EMGBF training of pronation and supination of the forearm is
difficult because of the cross talk between the EMG activity from the
pronators and supinators and other EMG present in the forearm;
EMGBF may be combined with angular BF in cases of severe
spasticity or flaccidity.

37. ◦ Targeted training of the lower limb is simpler than that of the
upper limb.
◦ Training of the lower limb need not follow the proximal-to-distal
progression for the upper limb.
◦ The primary functional goals are improved ambulation and to
develop a relatively limited number of stereotyped patterns used
during ambulation.
◦ One of the important areas of EMGBF training was for the treat-
ment of foot drop caused by paralysis of the ankle dorsiflexors
and spasticity of the plantar flexors.
◦ Other training protocols involve training of multiple joints
simultaneously to coordinate, such as the training of hip and
knee extension critical for the gait stance phase, hip flexion

38. ◦ with knee extension important during the terminal swing phase
of gait, and hip extension with knee flexion.
◦ BF retraining during ambulation focuses on specific gait timing,
because the coordination of muscles or joints depends on gait
phase.
◦ In this case, a gait event detection system such as footswitch is
essential.
◦ Continuously monitoring the gait performance, such as gait
symmetry, weight loading, or muscle recruitment has also been
reported.
◦ Auditory warning buzz provides discrete feedback only if the
monitored parameter is out of the desired range.

39. BALANCE REHABILITATION :
◦ Another major application of BF in stroke rehabilitation is the
training of balance control.
◦ Roughly 40% of stroke patients will experience a serious fall within
a year after having a stroke .
◦ Unsteadiness during stance, asymmetric weight loading, and
decreased ability to move within a weight-bearing posture have
been reported among stroke survivors.
◦ The training protocols address three components of the function:
steadiness, symmetry, and dynamic stability.
◦ In retraining of postural steadiness, stroke patients stand on a
force plate, wearing a fall arrest harness.

40. ◦ Patients are required to keep the cursor representing COF or
COP within a narrow range while they sway the body weight.
◦ To improve the control of postural symmetry, the force BF training
progresses from static standing to dynamic movements, such as
sit-to-stand transfers and stepping in place.
◦ The percentage of weight bearing on the nonparetic and paretic
leg is quantified and displayed visually and audibly.
◦ The goal of trainees is to equalize the weight loading on each leg.
◦ The training of postural steadiness and symmetry resulted in the
reduction in weight-bearing asymmetry.

41. ◦ However, stroke patients failed to reduce their spontaneous
sway amplitude and did not improve on functional measures.
◦ The dynamic postural control will be last trained.
◦ The patients are instructed to voluntarily move the COP/COF
cursor from one target to another in different directions
accurately without falling.
◦ The capability to transfer body weight and adopt a different
stance position is a prerequisite for safe mobility.
◦ Hence, training of dynamic stability is thought to have important
links to the function, but no strong evidence has been found to
support this contention.

42. SPINAL CORD INJURIES :
◦ Spinal cord injury (SCI) results in varying degrees of weakness
and sensory loss at and below (i.e., caudal to) the site of injury.
◦ The motor deficits may be represented as muscle weakness and
limb paralysis, spasticity, lost of normal bladder control, and
breathing difficulty.
◦ The primary goals for interfacing patients with SCI with EMGBF
are much the same as those outlined previously for stroke
patients.
◦ First, attempts are made to reduce hypermotor responses to
induced length changes in spastic muscles.

43. ◦ Such hyperactive behavior of spastic muscles may occur
during spontaneous episodes of clonus or during induced
clonic seizures, when the lower or upper extremity responds
to various tactile stimuli.
◦ Once the patient can reduce such responses in supine,
sitting, and ultimately standing postures, efforts are directed
toward recruitment of weak muscles.
◦ For patients with tetraparesis and obvious residual voluntary
movement, feedback combined with an exercise program
facilitated active range of motion (ROM) and improved
upper-extremity function.

44. ◦ Feedback may be beneficial for these patients because the
modality may be easily incorporated into exercise programs with
immobilized patients during the acute phase of injury; it provides
immediate information to the patient concerning the level of
voluntary muscle activity; and, by so doing, this modality may
help patients obtain spatial and temporal summation of muscle
potentials leading toward increased contractility, and therefore
preparing the patient for a more vigorous therapy program.
CEREBRAL PALSY AND TRAUMATIC BRAIN
INJURIES :
◦ Early EMGBF applications monitored the spastic muscles in
patients with cerebral palsy (CP) or traumatic brain injury (TBI).

45. ◦ EMGBF was employed to down-train the sensitivity of tonic
stretch reflex.
◦ Four young adults with CP reduced the involuntary muscle activity
and stretch reflex sensitivity.
◦ However, only one athetotic patient improved voluntary joint
control as a consequence of reducing the amount of involuntary
arm movement.
◦ EMGBF was also applied to down-train the gain of stretch reflex
for correction of muscle contracture.
◦ Although patients with CP significantly decreased the stretch
reflex, the contracture was not altered; thus, EMGBF might only
be useful for preventing the progress of muscle contracture.

46. ◦ With the view that the deficits of motor function in CP patients are
more related to deficits in strength and control than spasticity, the
recent applications of EMGBF shifted attention to the up-training
of muscle activity, muscle synergy, and joint control.
◦ Head position control using positional BF, control of drooling using
EMGBF, and trunk sitting posture control by angular or pressure
BF have been used with CP patients
MULTIPLE SCLEROSIS :
◦ Multiple sclerosis (MS) causes a variety of sensorimotor dys-
function, including muscle weakness, abnormal muscle tone,
difficulties in coordination and balance, problem in speech and
swallowing, fatigue, change in sensation, and bladder and bowel
control difficulties.

47. ◦ The abnormal fatigue induced by any form of training reduces the
usefulness of EMGBF for motor retraining.
◦ In selected patients, it may be useful in training muscle relaxation
of mild spasticity and general tenseness.
◦ For moderate and marked spasticity, he does not advocate
EMGBF, preferring one or another of the specific anti-spasticity
drugs.
◦ Head position BF training and self-stabilization of head position
during treadmill walking was compared between able-bodied and
MS subjects.
◦ Patients with MS had poor head control compared to healthy
subjects, which may partially explain the dynamic balance problem
of patients with MS.

48. ◦ Both self-stabilization of head position and BF training reduced
the amount of head motion; no difference between interventions
was observed.
◦ The training effects in MS patients, however, did not transfer to
the dynamic balance control in the Timed Up and Go test.
◦ Pelvis floor EMGBF has been applied to MS patients for the
treatment of incontinence or constipation.
◦ EMGBF was beneficial to alleviate some of the symptoms of
lower urinary tract dysfunction when combined with other
conventional training and was especially effective in MS
patients who had lower disability and a nonprogressive disease
course

49. DYSTONIAS AND DYSKINESIAS :
◦ Ignoring the many conflicting theories of etiology that provide no
clear guides to therapy, we briefly discuss here a number of
movement disorders that have responded well to behavioral
therapy featuring EMGBF.
◦ They present themselves mainly in isolated muscle groups;
spasmodic torticollis is the best example, but also included are
the rarer blepharospasm, hemifacial spasm, writer’s cramp, and
severe torsional dystonias of the torso (i.e., malignant dystonia
musculorum deformans).
PERIPHERAL NERVE DEGENERATION :
◦ Facial palsy causes weakness or paralysis of the facial muscles,
accompanied by other complications.

50. ◦ Synkinesis is one of the complications and is an abnormal
involuntary associated facial movement during blinking.
◦ The underlying mechanism of synkinesis is inappropriate
reinnervation of the regenerating facial nerve fiber to the facial
muscle EMGBF is an efficient rehabilitation intervention for
patients with facial palsy.
◦ Results from studies have shown that after EMGBF training,
there was substan-tial improvement in facial symmetry and
voluntary func-tions.
◦ Moreover, EMGBF was reported to be useful to further improve
the facial function in patients undergoing facial anastomosis
surgery.

51. ◦ POLYNEUROPATHY AND PERIPHERAL NEUROPATHY :
◦ Patients with diabetes might develop sensory neuropathy that
compromises proprioception.
◦ BF devices function as a bypass to close the motor control loop
for sensorimotor integration.
◦ Patients with sensory neuropathy demonstrated dysfunction on
balance control and increased rates of fall.
◦ A controlled trial tested BF of COG for balance retraining against
conventional therapy and found that BF is more efficacious.

52. PAIN MANAGEMENT AND BIOFEEDBACK :
◦ Related disciplines, especially psychotherapy and pain clinics,
widely use EMGBF for relaxation, both general and specific .
◦ In addition, skin temperature feedback training is used for treating
pain conditions normally not seen by rehabilitation clinicians (e.g.,
migraine) with generally good results.
◦ Acute and chronic back pain treatment with targeted surface
EMGBF, as an adjunct to conventional excises, has shown positive
effects on the strength of lumbar paraspinal muscle.
◦ Recently, advances in the ultrasound technique make the
noninvasive measurement of deep muscle activity in real time
possible.

53. SUMMARY AND CONCLUSION
◦ Biofeedback remains an important adjunct to the tools of the
rehabilitation therapies; it has been subjected to intensive
scien-tific scrutiny with controlled studies of varying quality
pervad-ing its history, and ineffective procedures are being
extricated.
◦ In addition to traditional, static BF training strategy, further
BF study may shift attention from static to task-oriented
biofeedback training, which may enhance motor functional
recovery.

54. ◦ Moreover, novel rehabilitation technologies such as VR,
therapeutic robots, and telerehabilitation are exciting and
have been introduced independently or combined with BF
applications.
◦ Collectively, the totality of advances among these
technologies may bring BF-based rehabilitation into a new
era.

55. VR BIOFEEDBACK