QUINTESSENCE INTERNATIONAL ORAL MEDICINE

John K. Brooks Numb chin syndrome associated with vertical root fracture and odontogenic infection

John K. Brooks, DDS1/Kevin G. Schwartz, DMD2/Alvin S. Ro, DDS3/Chang-Ching D. Lin, MD4

Numb chin syndrome (NCS) is a multifactorial neuropathic dis- nancy or metastatic disease. This report describes an unusual order associated with paresthesia to the chin, lip, and oral case of NCS developing synchronously with a vertical root mucosa, particularly arising as a sequela to various dental-re- fracture and odontogenic infection in a mandibular first molar. lated procedures or infections in the mandible. Timely elucida- Clinicians should consider the inclusion of a vertical root frac- tion of the underlying etiology is of paramount importance as ture as plausible cofactor for the development of NCS. the presentation of NCS could serve as a harbinger of malig- (Quintessence Int 2017;48: 225–230; doi: 10.3290/j.qi.a37643)

Key words: cracked tooth, inferior alveolar nerve, odontogenic infection, paresthesia

Numb chin syndrome (NCS), also referred to as numb ular and dentigerous cysts, osteomyelitis, odontoma), lip syndrome or mental nerve neuropathy, is a relatively systemic disorders (diabetes, systemic sclerosis, Paget’s uncommon neurosensory dysfunction to the chin, lip, disease, sickle cell anemia, sarcoidosis, amyloidosis, and oral mucosa. Typically, affected patients manifest vasculitis), viral (herpes zoster, human immunodefi- facial paresthesia, anesthesia, or dysesthesia unilater- ciency) and bacterial (Lyme disease, syphilis) infections, ally, and bilateral examples are extremely rare.1 Altered facial trauma, surgery, radiotherapy, pharmacologic sensations can involve perturbations arising centrally agents (metronidazole, zoledronic acid), benign tumors (skull base, leptomeninges) and peripherally (trigemi- (odontoma, schwannoma, neurofibromatosis), primary nal ganglion, and inferior alveolar and mental branches malignancies (solid, hematologic), paraneoplastic syn- of the trigeminal nerve). Neuropathy of the oral and drome, and metastatic dissemination (breast, prostate maxillofacial region is associated with a diversity of carcinoma, and myriad other less frequent histologic etiologies, such as local disease (pulpal necrosis, radic- subtypes).2-7 Although the literature is replete with case reports of NCS associated with infections of dental origin, the

1 Clinical Professor, Department of Oncology and Diagnostic Sciences, University presence of a vertical root fracture contributing to the of Maryland School of Dentistry, Baltimore, Maryland, USA. onset of the neurologic deficit has not been appreci- 2 Senior Attending, Department of Oral and Maxillofacial Surgery, Medstar Wash- ated.8-11 This article reports an unusual case of a ington Hospital Center, Washington, District of Columbia, USA. 3 Private Practice, Endodontics, Frederick, Maryland, USA. 48-year-old woman who developed NCS resulting from 4 Private Practice, Neurology, Germantown, Maryland, USA. a vertical root fracture concurrent with odontogenic

Correspondence: Dr John K. Brooks, Department of Oncology and infection in a mandibular first molar. Vertical root frac- Diagnostic Sciences, Room 7210, University of Maryland School of Den- tures should be included as a possible etiologic cofac- tistry, 650 West Baltimore Street, Baltimore, Maryland 21201-1586, USA. Email: [email protected] tor for the development of NCS.

VOLUME 48 • NUMBER 3 • MARCH 2017 225 QUINTESSENCE INTERNATIONAL Brooks et al

CASE PRESENTATION

A 48-year-old woman sought dental evaluation with her general dentist in October 2015 for intermittent spontaneous pain and pain upon mastication, both having recently increased in intensity, and mild sensi- tivity to cold stimuli without lingering, localized to the mandibular left posterior region. Of note, she reported a “burning” sensation and “tingling” that extended from the left angle of the mandible to the lower lip and chin, of 2 month’s duration. The patient’s medical his- tory was remarkable for chronic temporomandibular disorder (myofascial pain, bruxism) and ongoing man- Fig 1 Inconclusive periapical radiographic changes at presen- tation. agement by an oral and maxillofacial surgeon, chronic rhinitis, acne, roseacea, and gastroesophageal reflux disease. A magnetic resonance imaging (MRI) scan taken on July 2015 for evaluation of the temporoman- The patient returned to the oral and maxillofacial dibular joints showed a left anteriorly displaced disk surgeon in November 2015 and acknowledged that her without reduction. Within the last few months, she had facial pain had reduced somewhat in intensity and the experienced a marked increase in myofascial pain, hav- burning and paresthesia to her left lip and chin had ing previously gained moderate control with the use of abruptly ended the previous day. The clinical examination an occlusal guard, physical therapy, massage, chiro- did not reveal any palpable masses and a panoramic practic therapy, and a soft food diet. She also exhibited radiograph was unremarkable for any discreet periapical occasional episodes of clenching. Current medications pathoses (Fig 2). The MRI taken in July 2015 was reexam- were ethinyl estradiol and norgestimate, azelastine and ined and no pathologic processes were evident. The fluticasone nasal spray, loratadine, montelukast, dap- patient was advised to return for another assessment sone topical, doxycycline, and rabeprazole. The patient contingent on the recurrence of the paresthesia. estimated drinking 10 glasses of wine per week and The patient returned on January 2016 to her gen- had previously smoked approximately 1 ½ packs of eral dentist with increased tooth pain localized to the cigarettes per day for about 13 years. She denied any left mandible. During this interim, she reported recur- recent surgery or trauma to the head and neck. rent lip and chin paresthesia of varying intensity. The Clinical assessment noted moderate wear facets on mandibular left first molar was moderately tender to the mandibular left first molar, and use of articulating percussion and the patient was subsequently referred paper demonstrated increased occlusal contact in mul- to an endodontist for root canal therapy. Endodontic tiple sites on this tooth. The tooth was mildly tender to examination noted mild sensitivity to percussion, neg- percussion. An intraoral radiograph did not reveal ative response to cold (Endo-Ice Refrigerant Spray, definitive osseous changes; rather, a subtle radiolu- Coltène/Whaledent), and periodontal probings ranged cency apical to the mesial root was not considered from 2 to 4 mm in the affected region. Pronounced diagnostically significant (Fig 1). For palliation, a limited radiolucencies at the apices of the mesial and distal occlusal adjustment was performed to reduce contact roots were evident on a repeat periapical radiograph and the patient was referred to the oral and maxillofa- (Fig 3). The diagnosis was pulpal necrosis with chronic cial surgeon for further evaluation of the paresthesia apical periodontitis. Upon local anesthesia and rubber and supplemental imagery. dam isolation, the amalgam restoration of the mandib-

226 VOLUME 48 • NUMBER 3 • MARCH 2017 QUINTESSENCE INTERNATIONAL Brooks et al

Fig 2 Absence of apparent pathoses on panoramic radiograph. Note bilateral radiopacities situated anterior to the intervertebral space between C3 and C4 represent the greater horns of the hyoid bone.

ular left first molar was removed for endodontic access and ascertainment of the structural integrity. A necrotic pulp was confirmed and the floor of the pulp chamber exhibited a conspicuous crack projecting in a mesiodis- tal direction and extending apically along the distal root. As such, the tooth was deemed nonrestorable and the patient was referred to the oral and maxillofacial surgeon for an extraction. At 6 weeks postoperatively (March 2016), the extraction site was healing without incident. However, the patient had persistent intermittent paresthesia to her left chin and lip. Skin mapping was performed, which was essentially within normal limits for direc- Fig 3 Demonstration of periapical radiolucencies on the mesial and distal roots of the first molar (3 months after initial assess- tional brush stroke, touch, pressure and pain, as well as ment). two-point discrimination. Taking a precautionary ap- proach, computed tomography (CT) imagery without contrast was undertaken and was without any demon- orientation, remote and recent memory, and attention. strative pathologic changes. The patient was referred Ocular assessment demonstrated pupils that were to a neurologist for further evaluation. equal, round, and reactive to light, with normal fundi. At the April 2016 neurologic appointment, the The extraocular movements were intact and the visual patient admitted that her paresthesia was somewhat fields were full to visual confrontation; hearing was diminishing. The examination confirmed decreased undiminished. The cerebellar evaluation showed no facial sensation to soft touch discrimination in the left dystaxia. The extremities exhibited a normal strength, mandibular distribution branch of the trigeminal nerve. bulk, tone, and sensation, with a normal gait and shoul- The facial muscles were intact, and intraorally the soft der shrug. The reflexes were equal and symmetric at 2+. palate elevated in the midline and the tongue pro- As of September 2016, the paresthesia has contin- truded in the midline. Mental status showed normal ued to abate and the patient estimated that she has

VOLUME 48 • NUMBER 3 • MARCH 2017 227 QUINTESSENCE INTERNATIONAL Brooks et al

regained “95% to 97% of feeling” to her left lip and sive, MRI and CT scan without contrast can be of utility chin. She will be followed for any deleterious changes for comprehensive visualization of the head, base of of her neurologic status. skull, and mandible.13 Of relevance, in a study of 27 patients who were referred to a dental school with a chief complaint of unilateral numbness to the chin, DISCUSSION 63.0% (17/27) of cases were related to dental treat- This case report is significant for the constellation of ment, 14.8% (4/27) were associated with periapical overlapping presentations and symptomatologies, ini- inflammatory pathoses, and most notably, 22.2% (6/27) tiated with myofascial pain and odontalgia, and culmi- of the patients had been diagnosed with advance- nated with the development of mandibular trigeminal staged malignant or metastatic disease.14 dysesthesia. Furthermore, the intensification of the NCS has been attributed to various dental proced- pain arising from the mandibular left first molar could ures to mandibular premolars and molars, and very have exacerbated the preexisting myalgia. The infec- infrequently with canines.15 These clinical outcomes tion arising in the mandibular left first molar led to have included oral and maxillofacial surgery (exodontia, supra-occlusion, and likely triggered greater pain on orthognathic, implant placement), and to a lesser extent, mastication, promoting additional clenching and brux- endodontic treatment (over-instrumentation, extrusion ism, with ensuing increase in the myofascial pain. An of obturation material, disinfectant misusage [formocre- additional contingency was the patient’s intake of osol, paraformaldehyde, sodium hypochlorite, hydrogen doxycycline for roseacea, possibly serving to mask peroxide]), injudicious local anesthesia injection, ortho- overt expressions of the dental infection. Appropriate dontia, tooth restorations, and denture impingement on diagnostic imaging had been undertaken along with the mental nerve in an atrophied mandible.14,16-20 oral and maxillofacial surgical, endodontic, and neuro- The featured patient presented with concurrent logic evaluations. The patient was ultimately diagnosed vertical root fracture and pulpal necrosis; however, it with paresthesia synchronous with an odontogenic was impossible to distinguish which was the anteced- infection and a vertical root fracture, based on the ent event. The loss of vascularity, as seen in pulpless improvement following the extraction of the mandibu- and necrotic teeth, renders teeth more brittle and lar left first molar and at the exclusion of other likely poses a greater risk for the propagation of vertical root etiologic pathways. As far as could be determined, this fractures, in distinction to vital teeth.21 Vertical root case report appears to be the first documentation of fractures have been implicated with repetitive, undue, NCS and vertical tooth fracture. The typical signs and and eccentric occlusal forces, often observed in brux- symptoms of vertical root fractures have featured pain ism, clenching, and ill-chosen mastication of damaging on percussion, pain on palpation, and the presence of a objects (ice, hard candy, bones).22 The affected patient’s deep narrow periodontal pocket.12 parafunctional habits of clenching and bruxism con- The presentation of NCS is potentially ominous. The ceivably could have led to the formation of the deep- attending clinician should begin the investigation pro- seated vertical root fracture. In fact, an analysis of 227 cess with characterization of the sensory disturbance extracted teeth with vertical root fractures ascertained (region affected, chronology, signs and symptoms), evidence of bruxism in 35.1% of these teeth.23 establishing whether the patient has had any recent A probable mechanism that produced the paresthe- dental or medical procedures in the affected site, and sia in the present patient was the vertical fracture serv- the undertaking of a thorough review of systems. Diag- ing as a direct conduit for oral pathogens to the pulpal nostic imagery for suspected cases of NCS should be tissue. Alternatively, the pulpal necrosis could have initiated with a panoramic radiograph and regional been regarded as an aseptic infection, perhaps conse- periapical radiographs. When the etiology remains elu- quent to the multiplicity of restorative procedures

228 VOLUME 48 • NUMBER 3 • MARCH 2017 QUINTESSENCE INTERNATIONAL Brooks et al

performed, and the presence of the vertical root frac- and physical examination should include the determina- ture could have been simply an ancillary finding. In tion of the sensory disturbance (region affected, onset, either case, the pulpal infection could have triggered a signs and symptoms), establishing whether the patient cascade of events, beginning with release of various has had any recent procedures in the affected site, and microbial and host-related pro-inflammatory mediators a thorough review of systemic disease. Vertical root into the periapical bone, leading to edema accumula- fracture should be added to the list of etiologic factors tion, causing increased compression pressure and isch- for NCS. Once a dental etiology has been excluded, the emia on the inferior alveolar nerve, and finally resulting patient warrants further medical and neurologic assess- in the promotion of a temporary conduction block of ment in search of more serious morbidities. the inferior alveolar nerve.24,25 The commencement of NCS is not always predi- REFERENCES cated by the radiographic boundary of infection being 1. Tejani N, Cooper A, Rezo A, Pranavan G, Yip D. Numb chin syndrome: a case in direct contiguity to the affected neural structures. series of a clinical syndrome associated with malignancy. J Med Imaging Yeler et al9 reported a patient with NCS due to an Radiat Oncol 2014;58:700–705. 2. Schwartz O, Kvorning SA. Tooth exfoliation, osteonecrosis of the jaw and infected mandibular molar that displayed a periapical neuralgia following herpes zoster of the trigeminal nerve. Int J Oral Surg radiolucency several millimeters from the inferior alve- 1982;11: 364–371. 3. Bodner L, Oberman M, Shteyer A. Mental nerve neuropathy associated with olar nerve, as seen in the present patient. Analogously, compound odontoma. Oral Surg Oral Med Oral Pathol 1987;63:658–660. Di Lenarda et al8 documented a case of NCS secondary 4. Laurencet FM, Anchisi S, Tullen E, Dietrich PY. Mental neuropathy: report of five cases and review of the literature. Crit Rev Oncol Hematol 2000;34:71–79. to an infection in a mandibular premolar, whereby the 5. Divya KS, Moran NA, Atkin PA. Numb chin syndrome: a case series and discus- radiographic periapical pathosis was at a distance of sion. Br Dent J 2010;208:157–160. approximately 2 mm from the mental nerve. 6. Ryba F, Rice S, Hutchison IL. Numb chin syndrome: an ominous clinical sign. Br Dent J 2010;208:283–285. Recovery of NCS from an underlying odontogenic 7. Fusi-Schmidhauser T, Bardelli D. Spontaneous osteonecrosis of the jaw during infection is usually complete, ranging from 2 days to bisphosphonate therapy: an unusual etiology of the numb chin syndrome. J Pain Palliat Care Pharmacother 2016;3:206–209. 11 about 1 year. The present patient gradually began to 8. Di Lenarda R, Cadenaro M, Stacchi C. Paresthesia of the mental nerve induced experience sensory return within 9 weeks after the by periapical infection: a case report. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;90:746–749. extraction, with continuing improvement, and has 9. Yeler H, Özeʴ I, Kiliʴ E. Infection-related inferior alveolar and mental nerve attained 95% to 97% resolution at 9 months postopera- paresthesia: case reports. Quintessence Int 2004;35:313–316. 10. Ozkan BT, Celik S, Durmus E. Paresthesia of the mental nerve stem from peri- 26 tively. In contrast, Giuliani et al provided a case report apical infection of mandibular canine tooth: a case report. Oral Surg Oral Med of paresthesia concomitant with an abscess in a man- Oral Pathol Oral Radiol Endod 2008;105:e28–e31. 11. von Ohle C, ElAyouti A. Neurosensory impairment of the mental nerve as a dibular second molar, eventuating with incomplete sequel of periapical periodontitis: case report and review. Oral Surg Oral Med neuropathic recovery 1 year after endodontic therapy Oral Pathol Oral Radiol Endod 2010;110:e84–e89. 12. PradeepKumar AR, Shemesh H, Jothilatha S, Vijayabharathi R, Jayalakshmi S, and extraction. The authors speculated that the infec- Kishen A. Diagnosis of vertical root fractures in restored endodontically treat- tion could have caused irreversible neural injury, either ed teeth: a time-dependent retrospective cohort study. J Endod 2016;42: 1175–1180. directly to the myelin sheath of the inferior alveolar 13. Lossos A, Siegal T. Numb chin syndrome in cancer patients: etiology, response nerve or through the production of a “fibrotic-cicatricial to treatment, and prognostic significance. Neurology 1992;42:1181–1184. 14. Kalladka M, Proter N, Benoliel R, Czerninski R, Eliav E. Mental nerve neuropa- reaction.” Full sensory restoration is not always achiev- thy: patient characteristics and neurosensory changes. Oral Surg Oral Med able with the advent of NCS, particularly when related Oral Pathol Oral Radiol Endod 2008;106:364–370. 15. Knowles KI, Jergenson MA, Howard JH. Paresthesia associated with endodon- 27,28 to surgery, trauma, neoplasms, and systemic disease. tic treatment of mandibular premolars. J Endod 2003;29:768–770. 16. Kim YK, Kim SG, Kim JH. Altered sensation after orthognathic surgery. J Oral Maxillofac Surg 2011;69:893–898. 17. Ahonen M, Tjäderhane L. Endodontic-related paresthesia: a case report and CONCLUSION literature review. J Endod 2011;37:1460–1464. 18. da Costa Monini A, Martins RP, Martins IP, Martins LP. Paresthesia during The development of NCS is a neuropathic disorder with orthodontic treatment: a case report and review. Quintessence Int 2011;42: a potentially inauspicious outcome. The patient history 761–769.

VOLUME 48 • NUMBER 3 • MARCH 2017 229 QUINTESSENCE INTERNATIONAL Brooks et al

19. Zmener O. Mental nerve paresthesia associated with an adhesive resin restor- 24. Čolić M, Gazivoda D, Vučević D, Vasilijić S, Rudolf R, Lukić A. Proinflammatory ation: a case report. J Endod 2004;30:117–119. and immunoregulatory mechanisms in periapical lesions. Mole Immunol 20. Rashid N, Yusuf H. Intermittent mental paraesthesia in an edentulous mandi- 2009;47: 101–113. ble. Br Dent J 1997;182:189–190. 25. Al-Muharraqi MA, O’Sullivan EC. Unilateral facial nerve paralysis following an 21. Haueisen H, Gärtner K, Kaiser L, Trohorsch D, Heidemann D. Vertical root infected lower third molar. Int J Oral Maxillofac Surg 2010;39:192–195. fracture: prevalence, etiology, and diagnosis. Quintessence Int 2013;44: 26. Giuliani M, Lajolo C, Deli G, Silveri C. Inferior alveolar nerve paresthesia caused 467–474. by endodontic pathosis: a case report and review of the literature. Oral Surg 22. Yang SF, Rivera EM, Walton RE. Vertical root fracture in nonendodontically Oral Med Oral Pathol Oral Radiol Endod 2001;92:670–674. treated teeth. J Endod 1995;21:337–339. 27. Sarikov R, Juodzbalys G. Inferior alveolar nerve injury after mandibular third 23. Cohen S, Berman LH, Blanco L, Bakland L, Kim JS. A demographic analysis of molar extraction: a literature review. J Oral Maxillofac Res 2014;5:e1. vertical root fractures. J Endod 2006;32:1160–1163. 28. Lin CS, Wu SY, Huang HY, Lai YL. Systematic review and meta-analysis on incidence of altered sensation of mandibular implant surgery. PLoS One 2016;11:e0154082.

230 VOLUME 48 • NUMBER 3 • MARCH 2017