Spinal Cord Injuries and Pain Perception

This assignment delves into the connection between spinal cord injuries and altered pain perception. It examines research using electromyography (EMG) to study patients with both fibromyalgia and spinal cord injuries. The analysis focuses on how injuries interrupt reflex pathways and contribute to pain experiences. Specific details are provided about EMG data collection, interpretation, and the implications for understanding pain mechanisms in these patient populations.

Running head: MEASUREMENT INSTRUMENTS OF CENTRAL SENSITIZATION
CLINICAL SENSITIZATION
Name of the Student
Name of the University
Author note

1MEASUREMENT INSTRUMENTS OF CENTRAL SENSITIZATION
Measuring instrument for the nociception flexion reflex
The central sensitization is a state of the nervous system, which is involved in the
development and maintenance of chronic pain. This situation activates the noxious and non-
noxious stimuli to make the central nervous system hyperactive. This activation of the central
nervous system induces the feeling of pain in individuals. The Nociceptive Flexion Reflex (NFR)
is a nerve reflex, which is released from the spinal cord to protect the body from the damaging
stimuli (Ang et al., 2011). This is the withdrawal response of the body against any pain stimulus
and the reflex action is measurable in clinical settings. Measuring NFR is an objective and
reliable tool to measure the pain experience in central sensitization and chronic pain in
individuals. Desmeules et al. (2003) conducted a research to identify the neurophysiological
evidences that lead to central sensitization in patients with Fibromyalgia (FM). Researchers
conducted an experiment with total 164 outpatients were included using randomized controlled
trial method, in which, 85 patients were suffering from Fibromyalgia and 40 were non-FM
patients. The control group did not have any history of chronic pain. The physiotherapist selected
18 tender points in the patient’s body and a digital force of 4 kg was forced on that tender point
to assess the myalgia score. The evaluating physician's global impression (PGI) of the patient's
general status was recorded on a 5-point scale in which one is best or less pain felt (Desmeules et
al., 2003). The tools used in this research were aimed to identify pain (nonspontaneous),
assessment of the pain (using 2-fold subjective scale) and to access the nociceptive flexion reflex
or NFR to measure the reflex due to chronic pain. The results indicated that due to increased
level of pain, the group of patients with FM had decreased level of tolerance to pain and the NFR
level in those patients also decreased that determines the fact that decrease in reflex is associated
with increase in pain intensity. To measure the NFR, a cutaneous electrode was applied to

2MEASUREMENT INSTRUMENTS OF CENTRAL SENSITIZATION
measure the muscular reflex. The nerve, which was chosen for stimulation, was the sural nerve.
The NFR reflex test took very less time to perform however; several scales were used to
statistically analyze the measure of pain. The test needed very basic instruments used in
physiotherapy. Further, a trained or experienced physiotherapist can only perform the test as the
nerves or points, which were used to stimulate and get reflex, are known to experienced
physiotherapists. Another research done by Bezow et al. (2010) determined that continuous
nociceptive input from peripheral myofacial structure induces central sensitization and using
NFR to determine the pain threshold in the patients of tension-type headache helped the group of
researchers to measure the threshold of pain.
Measurement instrument for the Hoffman reflex
The Hoffman Reflex or H-reflex is the reflective reaction of the muscle after some
electrical stimulation of sensory fibers. The H-reflex test is done using electrical stimulator that
provides results using a square wave current having short duration and long amplitude. Further,
an electromyography machine or EMG is required to collect the data and record the response of
muscles (Abeles et al., 2007). This method is used to assess the changes in the excitation level of
the motor neuron pool. According to the research of Kumru et al. (2015), the researchers were to
identify the impact of spinal cord lesion level and severity of the injury on the level of H-reflex
excitability and recovery curve. Changes in the spinal cord reflexes can be originated from
different issues including changes in the descending pathway, and to determine the reason, they
chose 38 SCI or spinal cord injury patients and 18 normal individuals as control. They aimed to
identify the H-max responses and the recovery curve at interstimulus intervals and from 50-1000
ms were recorded in the process. Subjects were seated in a room with temperature between 22-25
degree Celsius As clinical assessment showed that nearly all of the SCI persons had equal

3MEASUREMENT INSTRUMENTS OF CENTRAL SENSITIZATION
irregularity in both lower limbs, the recordings and data examination were made on the right side
only. For electrophysiological readings, researchers used reusable bar recording electrodes
(Medelec) placed on the soleus muscle. They performed the entire research with a Medelec
Synergy electromyograph (Oxford Instruments, Surrey, UK). The assessment of the SCI injury
was done with the American Spinal Cord Injury Association (ASIA) Impairment Scale (Kumru
et al., 2015). The results of this experiment demonstrated that amplitude of the H-max correlates
with the level of injury and severity of the lesion and therefore it was determined that level of
severity is the reason behind the changes in the spinal cord reflex. The test utilizes very common
instruments of a physiotherapists and the electrical stimulator is the only instrument to measure
the electrical impulse. However, the nerves or areas, of which the impulse need to be measured,
are known to expert physiotherapists and therefore, this measurement tool can be used by
experienced physiotherapists for authentic measurement.
Measurement instrument for cutaneous silent period
The cutaneous silent period is known as the small interruption in the voluntary
contraction of nerves following strong electrical stimulation of the cutaneous nerve. This is a
protective reflex of the nervous system, which is mediated by the spinal inhibitory circuits and
this is reinforced due to the parallel modulation of the motor cortex. In the study done by Kilinc
et al. (2017), it was seen that increased responses to pain stimuli without any spontaneous pain
determined the role of hyper-excitability of different pain pathways. To determine that, the
researchers used cutaneous silent period parameter to demonstrate the level of spinal pain
pathway. For the research, the team of researchers chose 29 patients with Myofacial pain
syndrome or MPS and 30 another healthy patients were included as controls in the study. The
electrophysiological investigation was carried out in laboratory and after recording the stimulus,

4MEASUREMENT INSTRUMENTS OF CENTRAL SENSITIZATION
the recording electrodes were used to perform the CSP. They conducted three studies for the
assessment, such as electrophysiological study, nerve conduction study and CSP (Cutaneous
silent period) investigation. The electrophysiological study was performed with superficial
recording and stimulus electrode and pain threshold was recorded. The nerve conduction study
was done in nerves such as right median, ulnar, radial, sural, and superficial peroneal, and the
left medial plantar sensory nerves. Amplitudes, latencies, and further nerve conduction velocity
parameters were recorded for all these sensory and motor nerves. Same electrode was used for
CSP studies and pain threshold was measured for every individual (Kilinc et al., 2017).
Electromyography was used to statistically analyze the obtained data and it was found that
injuries in the spinal cord are responsible for the break or gap in stimulus or reflex flow in human
body. Another research done with the patients of fibromyalgia, the reflex mediated by the pain
was interrupted due to the presence of spinal cord injury and the injury was in the super spinal
level (Baek et al., 2016). However, the experiment lacks technical facility, as EMG audio
feedback machine was not present in the setup. Further, the experiment was performed without
any clinical objective method and therefore the clinical set up for the experiment need time and
cost to be successfully implemented. Further, the electrical impulse was collected from different
critical nerves and an experienced physiotherapist knows the points from which the impulses
were collected. Therefore, this test can only be performed by experienced physiotherapist or any
practice assistance, who has worked with any physiotherapist in the system. General physicians,
practiced or registered nurse cannot perform the test on their own.

5MEASUREMENT INSTRUMENTS OF CENTRAL SENSITIZATION
References
Abeles, A. M., Pillinger, M. H., Solitar, B. M., & Abeles, M. (2007). Narrative Review: The
Pathophysiology of FibromyalgiaPathophysiology of Fibromyalgia. Annals of internal
medicine, 146(10), 726-734.
Ang, D. C., Chakr, R., France, C. R., Mazzuca, S. A., Stump, T. E., Hilligoss, J., & Lengerich,
A. (2011). Association of nociceptive responsivity with clinical pain and the moderating
effect of depression. The Journal of Pain, 12(3), 384-389.
Baek, S. H., Seok, H. Y., Koo, Y. S., & Kim, B. J. (2016). Lengthened cutaneous silent period in
fibromyalgia suggesting central sensitization as a pathogenesis. PloS one, 11(2),
e0149248.
Bezov, D., Ashina, S., Jensen, R., & Bendtsen, L. (2011). Pain perception studies in tension‐type
headache. Headache: The Journal of Head and Face Pain, 51(2), 262-271.
Desmeules, J. A., Cedraschi, C., Rapiti, E., Baumgartner, E., Finckh, A., Cohen, P., ... &
Vischer, T. L. (2003). Neurophysiologic evidence for a central sensitization in patients
with fibromyalgia. Arthritis & Rheumatology, 48(5), 1420-1429.
Kilinc, O., Sencan, S., Ercalik, T., Koytak, P. K., Alibas, H., Gunduz, O. H., ... & Uluc, K.
(2018). Cutaneous silent period in myofascial pain syndrome. Muscle & nerve, 57(1).
Kumru, H., Albu, S., Valls‐Sole, J., Murillo, N., Tormos, J. M., & Vidal, J. (2015). Influence of
spinal cord lesion level and severity on H‐reflex excitability and recovery curve. Muscle
& nerve, 52(4), 616-622.