The authors have no acknowledgments.

Animals are treated and cared for according to the guidelines for pain research in conscious animals of the International Association for the Study of PAIN and in line with the Flemish and European regulations for animal research and the ARRIVE guidelines. The protocol is approved by the institutional Ethical Committee.
1. Animals
<ol>
	<li>Use male and female C57BL/6J mice (Janvier, 10 weeks old at arrival).</li>
	<li>House male and female mice separately in standard solid-...

Establishing the Mouse Model for Trigeminal Neuropathic Pain

<ol>
	<li>Costigan, M., Scholz, J., Woolf, C. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuropathic+pain:+a+maladaptive+response+of+the+nervous+system+to+damage.">Neuropathic pain: a maladaptive response of the nervous system to damage.</a> Annu Rev Neurosci. 32, 1-32 (2009).</li><li>Torrance, N., Smith, B. H., Bennett, M. I., Lee, A. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+epidemiology+of+chronic+pain+of+predominantly+neuropathic+origin.+Results+from+a+general+population+survey.">The epidemiology of chronic pain of predominantly neuropathic origin. Results from a general population survey.</a> J Pain. 7, 281-289 (2006).</li><li>Jensen, T. S., Gottrup, H., Sindrup, S. H., Bach, F. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+clinical+picture+of+neuropathic+pain.">The clinical picture of neuropathic pain.</a> Eur J Pharmacol. 429 (1-3), 1-11 (2001).</li><li>Bennett, G. J., Xie, Y. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+peripheral+mononeuropathy+in+rat+that+produces+disorders+of+pain+sensation+like+those+seen+in+man.">A peripheral mononeuropathy in rat that produces disorders of pain sensation like those seen in man.</a> Pain. 33 (1), 87-107 (1988).</li><li>Backonja, M. M., Stacey, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuropathic+pain+symptoms+relative+to+overall+pain+rating.">Neuropathic pain symptoms relative to overall pain rating.</a> J Pain. 5, 491-497 (2004).</li><li>Basbaum, A. I., Campbell, J. N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measurrement+and+New+Technologies.">Measurrement and New Technologies.</a> Emerging Strategies for the Treatment of Neuropathic Pain. , (2006).</li><li>Mogil, J. S., Crager, S. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=What+should+we+be+measuring+in+behavioral+studies+of+chronic+pain+in+animals.">What should we be measuring in behavioral studies of chronic pain in animals.</a> Pain. 112, 12-15 (2004).</li><li>Vierck, C. J., Campbell, J. N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+Studies+of+Pain:+Lessons+for+Drug+Development.">Animal Studies of Pain: Lessons for Drug Development.</a> Emerging Strategies for the Treatment of Neuropathic Pain. , (2006).</li><li>Deseure, K., Adriaensen, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Nonevoked+facial+pain+in+rats+following+infraorbital+nerve+injury+a+parametric+analysis.">Nonevoked facial pain in rats following infraorbital nerve injury a parametric analysis.</a> Physiol Behav. 81 (4), 595-604 (2004).</li><li>Deseure, K., Hans, G. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chronic+constriction+injury+of+the+rat's+infraorbital+nerve+(IoN-CCI)+to+study+trigeminal+neuropathic+pain.">Chronic constriction injury of the rat's infraorbital nerve (IoN-CCI) to study trigeminal neuropathic pain.</a> J Vis Exp. (103), e53167 (2015).</li><li>Mogil, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Animal+models+of+pain:+progress+and+challenges.">Animal models of pain: progress and challenges.</a> Nat Rev Neurosci. 10 (4), 283-294 (2009).</li><li>Wilson, S. G., Mogil, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Measuring+pain+in+the+(knockout)+mouse:+big+challenges+in+a+small+mammal.">Measuring pain in the (knockout) mouse: big challenges in a small mammal.</a> Behav Brain Res. 125 (1-2), 65-73 (2001).</li><li>Ding, W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+improved+rodent+model+of+trigeminal+neuropathic+pain+by+unilateral+chronic+constriction+injury+of+distal+infraorbital+nerve.">An improved rodent model of trigeminal neuropathic pain by unilateral chronic constriction injury of distal infraorbital nerve.</a> J Pain. 18 (8), 899-907 (2017).</li><li>Hardt, S., Fischer, C., Vogel, A., Wilken-Schmitz, A., Tegeder, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Distal+infraorbital+nerve+injury:+a+model+for+persistent+facial+pain+in+mice.">Distal infraorbital nerve injury: a model for persistent facial pain in mice.</a> Pain. 160 (6), 1431-1447 (2019).</li><li>Krzyzanowska, A., Avenda&#241;o, C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Behavioral+testing+in+rodent+models+of+orofacial+neuropathic+and+inflammatory+pain.">Behavioral testing in rodent models of orofacial neuropathic and inflammatory pain.</a> Brain Behav. 2 (5), 678-697 (2012).</li><li>Martin, Y. B., Malmierca, E., Avenda&#241;o, C., Nu&#241;ez, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Neuronal+disinhibition+in+the+trigeminal+nucleus+caudalis+in+a+model+of+chronic+neuropathic+pain.">Neuronal disinhibition in the trigeminal nucleus caudalis in a model of chronic neuropathic pain.</a> Eur J Neurosci. 32 (3), 399-408 (2010).</li><li>Deseure, K., Hans, G. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Behavioral+study+of+non+evoked+orofacial+pain+following+different+types+of+infraorbital+nerve+injury+in+rats.">Behavioral study of non evoked orofacial pain following different types of infraorbital nerve injury in rats.</a> Physiol Behav. 138, 292-296 (2015).</li><li>Vuralli, D., Wattiez, A. S., Russo, A. F., Bolay, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Behavioral+and+cognitive+animal+models+in+headache+research.">Behavioral and cognitive animal models in headache research.</a> J Headache Pain. 20 (1), 11 (2019).</li><li>Krzyzanowska, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assessing+nociceptive+sensitivity+in+mouse+models+of+inflammatory+and+neuropathic+trigeminal+pain.">Assessing nociceptive sensitivity in mouse models of inflammatory and neuropathic trigeminal pain.</a> J Neurosci Methods. 201 (1), 46-54 (2011).</li></ol>

In rats, it has been previously argued that an intra-orbital approach to the IoN is preferable, considering the importance of intact fine musculature controlling complex whisking patterns in vibrissotactile discrimination and the relative distance of the mid-line incision to the cutaneous infraorbital nerve territory10. Others have argued that a distal approach via an incision into the hairy skin caudal to the vibrissal pad has a number of benefits13,<sup class="...

Neuropathic pain arises from damage to the somatosensory nervous system, leading to abnormal transmission of sensory signals to the brain. Somatosensory nerve damage does not always lead to neuropathic pain, but the prevalence increases with the severity of clinical neuropathy1,2. Neuropathic pain patients experience specific symptoms such as spontaneous sensations (burning, pins and needles, electric sensations) and abnormally intense or prolonged pain to innocuous or noxious stimulation that tend to become chronic and resistant to treatment with conventional pain medication3. Significant progress in the field of neuropathic pain research stems from the discovery that loosely constricting ligatures around the sciatic nerve in rats leads to behaviors resembling human neuropathic pain conditions4. The animals display reduced thresholds to heat, cold, and mechanical stimulation, and exhibit nocifensive behaviors. Despite the inherent biological differences in pain processing between humans and rodents, animal models are a valuable tool for studying the underlying mechanisms in the development of neuropathic pain and testing newly proposed treatment strategies.
Sensory reflex-based pain testing paradigms have been extensively used in neuropathic pain models, but measuring ongoing pain or other frequently accompanied disturbances (sleeping disorder, depression, anxiety) has not received sufficient attention considering that these are common clinical symptoms affecting quality of life5,6,7,8. Face grooming behavior in rats has been documented as a measure of spontaneous neuropathic pain following chronic constriction injury (CCI) of the infraorbital nerve (IoN)9,10. In addition, rats also develop hyperresponsiveness to mild tactile stimulation of the IoN territory, which is indicative of mechanical allodynia.
Compared to mice, because of their larger size, rats are better suited for surgical injuries. However, mice offer cost and space efficiency and require smaller drug quantities. Also, the advent of transgenic technology has further boosted the use of mice11,12. Therefore, the overall goal of this procedure is to perform a surgical infraorbital nerve injury in mice, similar to that in rats, that induces changes in spontaneous and evoked behavior for the study of trigeminal neuropathic pain.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Chromic catgut (6-0)</td>
			<td>Dynek&#160;</td>
			<td>CG602D</td>
			<td>ligatures</td>
		</tr>
		<tr>
			<td>Cotton applicator</td>
			<td>Pharmacy</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Digital video camera</td>
			<td>Sony</td>
			<td>HDR-CX330E</td>
			<td></td>
		</tr>
		<tr>
			<td>Dumont #5 forceps</td>
			<td>Fine Science Tools</td>
			<td>11251-10</td>
			<td></td>
		</tr>
		<tr>
			<td>Dumont forceps - Micro-blunted tips (#5/45)</td>
			<td>Fine Science Tools</td>
			<td>11253-25</td>
			<td></td>
		</tr>
		<tr>
			<td>Duratears</td>
			<td>Alcon</td>
			<td>0037-820</td>
			<td>ophthalmic ointment</td>
		</tr>
		<tr>
			<td>Hooked ligation aid</td>
			<td>Fine Science Tools</td>
			<td>18062-12</td>
			<td></td>
		</tr>
		<tr>
			<td>Ketalar</td>
			<td>Pfizer</td>
			<td></td>
			<td>ketamine (50 mg/mL)</td>
		</tr>
		<tr>
			<td>Operation microscope</td>
			<td>Kaps</td>
			<td>SOM 62</td>
			<td></td>
		</tr>
		<tr>
			<td>Precision cotton swab</td>
			<td>Qosina</td>
			<td>10225</td>
			<td></td>
		</tr>
		<tr>
			<td>Precision trimmer</td>
			<td>Philips</td>
			<td>HP6392/00</td>
			<td></td>
		</tr>
		<tr>
			<td>Rompun</td>
			<td>Bayer</td>
			<td></td>
			<td>xylazine (2%)</td>
		</tr>
		<tr>
			<td>Scissors - blunt tips</td>
			<td>Fine Science Tools</td>
			<td>14574-09</td>
			<td></td>
		</tr>
		<tr>
			<td>Semmes-Weinstein Von Frey Aesthesiometer kit</td>
			<td>Stoelting</td>
			<td>58011</td>
			<td></td>
		</tr>
		<tr>
			<td>Vicryl Rapide</td>
			<td>Ethicon</td>
			<td>MPVR489H</td>
			<td>sutures</td>
		</tr>
	</tbody>
</table>

chronic constriction injury of the distal infraorbital nerve (dion-cci) in mice to study trigeminal neuropathic pain

Animal models remain necessary tools to study neuropathic pain. This manuscript describes the distal infraorbital nerve chronic constriction injury (DIoN-CCI) model to study trigeminal neuropathic pain in mice. This includes the surgical procedures to perform the chronic constriction injury and the postoperative behavioral tests to evaluate the changes in spontaneous and evoked behavior that are signs of ongoing pain and mechanical allodynia. The methods and behavioral readouts are similar to the infraorbital nerve chronic constriction injury (IoN-CCI) model in rats. However, important changes are necessary for the adaptation of the IoN-CCI model to mice. First, the intra-orbital approach is replaced by a more rostral approach with an incision between the eye and the whisker pad. The IoN is thus ligated distally outside the orbital cavity. Secondly, due to the higher locomotor activity in mice, allowing rats to move freely in small cages is replaced by placing mice in custom-designed and constructed restraining devices. After DIoN ligation, mice exhibit changes in spontaneous behavior and in response to von Frey hair stimulation that are similar to those in IoN-CCI rats, i.e., increased directed face grooming and hyperresponsiveness to von Frey hair stimulation of the IoN territory.

Author Spotlight: Utilizing Infraorbital Nerve Ligation in Mice for Investigating Trigeminal Neuropathic Pain and Treatment Strategies

Chronic Constriction Injury of the Distal Infraorbital Nerve (DIoN-CCI) in Mice to Study Trigeminal Neuropathic Pain

The overall goal of this procedure is to perform an infraorbital nerve injury in mice to study the development of trigeminal neuropathic pain and to test new treatment strategies. Isolated phase grooming behavior after infraorbital nerve ligation is one of the few animal models to study spontaneous neuropathic pain. But its use has long been hampered by the complexity of performing an infraorbital nerve ligation.Compared to sensory reflex based pain testing, such as from fray or withdrawal responses from heat or cold stimulation, measuring spontaneous or ongoing pain has not received sufficient attention, considering that this is an important clinical symptom affecting quality of life. The distal approach to the infraorbital nerve has the advantage of being a surgically less demanding procedure than the intraorbital approach. It is minimally invasive, and can be performed without using a stereotaxic frame.

DIoN-CCI mice show a strong postoperative increase in time spent on isolated face grooming and the number of isolated face grooming episodes (Figure 3). The strongest increase occurs during the first postoperative week and then becomes smaller during the following weeks but is significantly increased for at least 6 weeks. Face grooming during body grooming is more or less unaffected.
DIoN-CCI mice are almost completely unresponsive to ipsilateral mechanical stimul...

Watch this Scientific Journal Video about Utilizing Infraorbital Nerve Ligation in Mice for Investigating Trigeminal Neuropathic Pain and Treatment Strategies at JoVE.com

Chronic constriction injury of the distal infraorbital nerve in mice induces changes in spontaneous behavior (increased face grooming activity) and nocifensive behavior in response to tactile stimulation (hyperresponsiveness to von Frey hair stimulation) that are signs of ongoing pain and allodynia and serves as a model for trigeminal neuropathic pain.

Animal models remain necessary tools to study neuropathic pain. This manuscript describes the distal infraorbital nerve chronic constriction injury ...