Research articleCortical modulation of brainstem circuits is abnormal in cervical dystonia
Introduction
Blink reflex (BR) is a protective response for eyes and is obtained after different kinds of stimuli, such as trigeminal supraorbital branch stimulation or median nerve stimulation at wrist (hand-evoked BR) [1]. The generator of the hand-evoked BR is localized in brainstem [2,3], however, it is assumed to be under the control of top-down modulation. Sambo et al. [4,5] previously showed the enhancement of hand-evoked BR in the peripersonal space of face and they attributed the hand-evoked BR changes in the nearby environment to the tonic top-down modulation exerted by association areas such as the premotor cortex and ventral intraparietal area.
Cervical dystonia leads to abnormal contraction of the muscles of the neck and, sometimes, the shoulders. Decreased inhibition, sensory dysfunction, and abnormal plasticity are common pathophysiological factors in all types of dystonia [6]. Increased excitability of brainstem reflexes is known in cervical dystonia and is indicative of increased brainstem interneuron excitability [7,8].
Here, we aimed to investigate changes of hand-evoked BR in peripersonal space to understand cortical contribution in pathophysiology of cervical dystonia. We first tested hand-evoked BR in a group of cervical dystonia patients in comparison to healthy subjects. Second, we compared hand-evoked BR findings in peripersonal space and extrapersonal space of face. This investigation will also provide to examine the differences in top-down modulation of hand-evoked BR in patients with cervical dystonia exhibiting and not exhibiting sensory trick.
Section snippets
Patients
We recruited 30 consecutive patients who were seen in our movement disorders outpatient clinic with a diagnosis of idiopathic cervical dystonia. However, seven patients with cervical dystonia did not have hand-evoked BR at baseline. Therefore, they were excluded from the study and 23 patients (15 women, 65.2%, mean age: 41.5 ± 11.2) were included. The study also excluded patients who had involuntary contractions of the facial muscles and those who had their facial muscles treated with botulinum
Results
Between-group analysis of hand-evoked BR parameters in the extrapersonal space showed mean latencies of hand-evoked BR were similar between groups of patients and healthy subjects (p = 0.217) whereas amplitude and AUC were significantly high in patients with cervical dystonia (p = 0.009 and 0.023, respectively, t-test for independent samples).
In-group analysis (peripersonal space vs. extrapersonal space) among healthy subjects disclosed there was a trend for a higher hand-evoked BR amplitude
Discussion
The major findings in this study were as follows: i. the normal enhancement of hand-evoked BR in the peripersonal space of face was lost in cervical dystonia; ii. the reduction of hand-evoked BR magnitude in peripersonal space was also observed in cervical dystonia patients exhibiting sensory trick; iii. no change of hand-evoked BR magnitude in the peripersonal space was observed in cervical dystonia patients without sensory trick.
In cervical dystonia and other kinds of dystonia, there exists a
Funding sources
None.
Conflicts of interest
None of the authors have potential conflicts of interest to be disclosed.
References (23)
- et al.
Deficient median nerve prepulse inhibition of the blink reflex in cervical dystonia
Clin. Neurophysiol.
(2016) - et al.
Parieto-frontal interactions, personal space, and defensive behavior
Neuropsychologia
(2006) - et al.
Sensorimotor network in cervical dystonia and the effect of botulinum toxin treatment: a functional MRI study
J. Neurol. Sci.
(2011) - et al.
Changes in cortical and pallidal oscillatory activity during the execution of a sensory trick in patients with cervical dystonia
Exp. Neurol.
(2007) 3rd ed.
- et al.
Somatosensory-evoked blink response: investigation of the physiological mechanisms
Brain
(1998) - et al.
The somatosensory blink reflex in upper and lower brainstem lesions
Muscle Nerve
(2011) - et al.
Defensive peripersonal space: the blink reflex evoked by hand stimulation is increased when the hand is near the face
J. Neurophysiol.
(2012) - et al.
To blink or not to blink: fine cognitive tuning of the defensive peripersonal space
J. Neurosci.
(2012) - et al.
Emerging concepts in the physiological basis of dystonia
Mov. Disord.
(2013)
Blink reflex studies in focal dystonias: enhanced excitability of brainstem interneurons in cranial dystonia and spasmodic torticollis
Mov. Disord.
Cited by (4)
The sensorimotor theory of pathological pain revisited
2022, Neuroscience and Biobehavioral ReviewsCitation Excerpt :People with migraine demonstrated a greater overall hand blink reflex than controls, especially if they were experiencing a headache at the time of testing (Ayas et al., 2020), although the typical spatial modulation was not found. People with cervical dystonia also showed a greater hand blink response than controls and an inversion of the normal spatial modulation (Öztürk et al., 2018). Taken together, these findings suggest that there is abnormal higher-order cortical modulation of the brainstem reflex in dystonia, headache/orofacial pain, and neuropathic pain.
Feedback-dependent neuronal properties make focal dystonias so focal
2021, European Journal of NeuroscienceModulation of the somatosensory blink reflex in the peripersonal space is defective in episodic migraine
2020, Pain Medicine (United States)Spontaneous, Voluntary, and Reflex Blinking in Clinical Practice
2019, Journal of Clinical Neurophysiology