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The Importance of Clinical Features and Computed Tomographic Findings in Numb Chin Syndrome
CLINICAL PRACTICE
C A SE REPOR T
The importance of clinical features and computed tomographic findings in numb chin syndrome A report of two cases Izumi Yoshioka, DDS, PhD; Shunji Shiiba, DDS, PhD; Tatsurou Tanaka, DDS, PhD; Takeshi Nishikawa, DDS; Eiji Sakamoto, DDS, PhD; Shinji Kito, DDS, PhD; Masafumi Oda, DDS; Nao Wakasugi-Sato, DDS, PhD; Shinobu Matsumoto-Takeda, DDS, PhD; Shigeyuki Kagawa, DDS; Osamu Nakanishi, DDS, PhD; Kazuhiro Tominaga, DDS, PhD; Yasuhiro Morimoto, DDS, PhD
umb chin syndrome (NCS) is a rare condition that is the result of mental nerve neuropathy, which is a sensory neuropathy. The symptoms of NCS include numbness of the skin of the lips and chin, the gingiva and the teeth, most often due to metastasis of a primary malignancy of the mandible.1-5 Other causes of NCS are dental infection, facial trauma, osteomyelitis, sickle cell anemia, diabetes mellitus and HIV infection. There are numerous reports of NCS in the medical literature and only a few in the dental literature.1,3-5 Most dentists are not aware of NCS and its clinical manifestations. In patients with NCS and accompanying tooth pain, dentists may unknowingly perform unnecessary and useless endodontic therapy
N
ABSTRACT Background. Dentists need to be aware of the relationship between malignancies and paresthesia or complete loss of sensation in a jaw segment. In particular, dentists should be aware of numb chin syndrome (NCS) and its clinical manifestations, as well as the limitations of using panoramic radiographs to detect the causative malignancy. Case Descriptions. The authors report two cases of paresthesia in the mental region. No lesions were readily apparent on the patients’ panoramic radiographs. To exclude the presence of disease in the mandible that could have been responsible for the NCS, the authors obtained computed tomographic (CT) images. They identified metastases to the mandible from primary malignant tumors elsewhere in the body. Clinical Implications. To prevent misdiagnosis of NCS, dentists need to be aware of the clinical manifestations of NCS, the need for CT imaging, the shortcomings of panoramic radiographs and the value of obtaining detailed and accurate medical and dental histories from patients. Key Words. Numb chin syndrome; paresthesia; panoramic radiograph; metastasis; malignancy; jaws. JADA 2009;140(5):550-554.
Dr. Yoshioka is an associate professor, Department of Oral and Maxillofacial Surgery, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Shiiba is an assistant professor, Department of Control of Physical Functions, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Tanaka is an assistant professor, Department of Oral Diagnostic Science, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Nishikawa is an instructor, Department of Oral and Maxillofacial Surgery, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Sakamoto is an assistant professor, Department of Control of Physical Functions, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Kito is an assistant professor, Department of Oral Diagnostic Science, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Oda is a postgraduate student, Department of Oral Diagnostic Science, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Wakasugi-Sato is an assistant professor, Department of Oral Diagnostic Science, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Matsumoto-Takeda is an assistant professor, Department of Oral Diagnostic Science, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Kagawa is an intern, Department of Oral Diagnostic Science, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Nakanishi is a professor and the chairman, Department of Control of Physical Functions, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Tominaga is a professor and the chairman, Department of Oral and Maxillofacial Surgery, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Morimoto is a professor and the chairman, Department of Oral Diagnostic Science, Kyushu Dental College, 2-6-1 Manazuru, Kokura-kita, Kitakyushu, Fukuoka 803-8580, Japan, e-mail “[email protected]”. Address reprint requests to Dr. Morimoto.
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May 2009
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C L I N I C A L P R A C T I C E CASE REPORT
to treat the painful teeth. Dentists should be able to recognize the clinical manifestations of NCS, such as paresthesia and gingival or tooth pain. They also should be aware that NCS can be the result of metastasis of a primary tumor to the mandible that cannot be identified on panoramic radiographs but that can be identified on computed tomographic (CT) images. Thus, CT images are an important tool that can be used to assess patients who exhibit the clinical manifestations of NCS. We present two cases that highlight the need for CT imaging, the shortcomings of panoramic radiographs and the need for dentists to investigate the status of a patient’s cancer and the clinical manifestations of NCS. CASE REPORTS
Case 1. In early 2003, a private practitioner referred a 69-year-old man with chief complaints of paresthesia and pain in the left mental region to our dental hospital at Kyushu Dental College, Kitakyushu, Fukuoka, Japan. In 2000, the patient’s prostate cancer had been diagnosed and treated with local excision and hormone treatment. He subsequently was seen in the urology department of another hospital and was prescribed the chemotherapeutic agent estramustine to treat his prostate cancer. The patient also reported that he had received a diagnosis of having no particular brain pathology after having undergone brain surgery in 2007. In the patient’s initial 2003 visit to the dental hospital, he reported that paresthesia and pain began about two weeks earlier and the severity had been increasing. With respect to the degree of the paresthesia, the patient gave a score of 3 for both touch (as assessed by using a small brush) and pain (as assessed by using a safety pin stick) sensation in the left mental region and a score of 10 for both on the unaffected right side. We used 10-point scales to assess touch and pain in which in which 1 represented no pain and no feeling of touch, respectively, and 10 represented the most pain and the most touch sensation, respectively. Lip movement and taste sensation were normal. We suspected that the patient had NCS and obtained a panoramic radiograph. On the radiograph, we noted generalized horizontal bone loss and obvious bony defects that suggested severe periodontal disease (Figure 1A). Consequently, the uniform destruction and widening of the periodontal ligament space, the periapical radi-
olucency with poorly defined borders and the thinning of the lower cortical border of the mandible could have been overlooked easily because the findings were unclear or had been dismissed as further evidence of periodontal disease instead of suggesting that malignant disease is present (Figure 1A). To exclude the presence of bone lesions in the mandible that could have been responsible for NCS, the patient underwent CT scanning (Figures 1B and 1C). On the CT images, we saw the typical findings of metastasis to the mandible from prostate cancer. These findings included osteoblastic changes in the left side of the mandible (Figure 1B) and destruction of cortical bone (Figure 1C). The patient underwent technetium Tc 99m methylene diphosphonate nuclear medicine bone scanning at about the same time. The results showed an increased uptake of technetium Tc 99m methylene diphosphonate in the left side of the mandible, a right rib and the spine (Figure 1D). We biopsied the lesions in the left side of the mandible and, on the basis of the results, made a diagnosis of prostate cancer (which was a recurrence of the prostate cancer the patient had had in 2000). The patient’s prostate specific antigen (PSA) level could not be obtained in our hospital. He was treated with chemotherapy and hormone treatment at another hospital, and he died a year later. Case 2. In early 2008, a 79-year-old woman with a chief complaint of paresthesia of the left mental region—including the lips but without pain—visited our dental hospital. The paresthesia had begun about one week earlier and had been increasing. With respect to the degree of paresthesia, the electric detection threshold, as determined by means of electric stimulators, was twice as high for the left mental region as it was for the right. Lip movement and taste sensation were normal. The patient had undergone chemotherapy for multiple myeloma in 2000. On the basis of the patient’s medical and dental histories and our clinical findings, we suspected that she had NCS. We obtained a panoramic radiograph that showed asymmetry in the radiographic appearance of the left and the right sides of the mandible and thinning of the lower cortical border of the mandible (Figure 2A, page ABBREVIATION KEY. CT: Computed tomographic. NCS: Numb chin syndrome. PSA: Prostate specific antigen. JADA, Vol. 140
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A
B
C
D
Figure 1. Case 1. Imaging in a 69-year-old man with paresthesia and pain in the left mental region. A. Panoramic radiograph showing features suggesting generalized periodontal disease, especially in relation to the mandibular left molars. The widening of the periodontal ligament, a periapical radiolucency with poorly defined borders and thinning of the lower cortical border of the mandible (suggestive of a malignancy) can be overlooked easily. B. Axial computed tomographic (CT) image with a soft-tissue window showing osteoblastic changes (arrowhead). C. Axial CT image with a bone window showing destruction of the cortical bone (white arrows). D. A technetium Tc 99m methylene diphosphonate nuclear medicine bone scan image showing increased uptake of technetium Tc 99m methylene diphosphonate in the left side of the mandible (black arrow), a right rib (black arrowhead) and the spine (white arrow).
553). These findings on the panoramic radiograph could have been overlooked easily because the findings were unclear. To exclude the possibility that bone lesions in the mandible could be responsible for NCS, the patient underwent CT scanning (Figures 2B and 2C). We saw the typical findings of metastasis to the mandible from multiple myeloma on the CT images, as well as bilateral destruction of the cortical bone in the mandible (Figure 2C). Subsequently, the patient was referred to another hospital that had a hematology service, in which blood tests were performed. The results of the tests showed that her beta2 monoclonal globulin level was high (23.3 milligrams per liter), total protein level was relatively high (8.9 grams per deciliter), gamma globulin level was high (34.5 percent), and immunoglobulin G level was high (3,862 mg/dL). Her blood urea nitrogen level was high (33.3 mg/dL), and her creatinine level 552
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was high (2.24 mg/dL). The results of a test to detect Schilling leukemia (acute monocytic leukemia) showed plasma cells with dysplasia. The patient has been undergoing chemotherapy and follow-up treatment for multiple myeloma. DISCUSSION
NCS is a rare syndrome that manifests as numbness in the regions innervated by the mental nerve, including the lip, chin, gingiva and teeth. It most often is due to metastasis of primary malignancy to the mandible.1-5 The main cause of NCS includes perineural spread of metastatic disease or compression of nerve tissue by a tumor. Other causes are dental infection, facial trauma, osteomyelitis, sickle cell anemia, diabetes mellitus and HIV infection. No discernible pattern and no male or female preponderance has been found in NCS.1 Smith and colleagues1 reported that a substantial number of NCS cases have been reported in the
May 2009
Copyright © 2009 American Dental Association. All rights reserved. Reprinted by permission.
C L I N I C A L P R A C T I C E CASE REPORT
be performed to diagnose numbness manifesting as paresthesia in the mental region. The presence of numbness, manifesting as paresthesia, can be evaluated easily by comparing the scores of the touch and pain tests for the right and left sides. If there is a significant difference between the scores for A touch test, pain test or both for the two sides, a diagnosis of NCS should be suspected. Then a patient’s report of abnormal sensation should be considered. In the first case we reported, we evaluated paresthesia on the basis of the patient’s medical and dental histories and the sensory examination. In the second case, we determined the patient’s B C electric detection threshold, which is useful for Figure 2. Case 2. Imaging in a 79-year-old woman with paresthesia in the left mental region. A. Panoramic radiograph showing features of bone destruction that could be overlooked readily or assessing the presence of dismissed as a variation of normal: a large radiolucency in the left side of the mandible, not seen on paresthesia.6 However, the right side, and thinning of the lower cortical border of the mandible. B . Axial computed tomographic (CT) image with a soft-tissue window showing soft-tissue opaque structures (black arrows) specific tools such as bilaterally as typical findings of metastasis to the mandible from multiple myeloma. C . Axial CT image electric stimulators are with a bone window showing bilateral destruction of cortical bone and sponginess (black arrows). needed to determine the medical literature but only a few have been patient’s electric detection threshold. Therefore, reported in the dental literature.1,3-5 Most dentists we advocate that dentists conduct touch and pain are unaware of NCS and its clinical manifestasensation tests to diagnose numbness in the tions. Dentists who are unaware of NCS and have mental region. Usually, only the sensory innervaa patient who has a complaint of paresthesia in tion is affected, since the inferior alveolar nerve the mental region may obtain panoramic radihas no motor fibers. Since motor function is ographs, other dental radiographs or both. Howintact, movement of the lower lip is possible in ever, in cases similar to those we reported, if no cases of NCS. In the two cases we reported, the specific abnormalities are seen on the radipatients’ lip movements and taste sensations ographs, dentists may conclude that the mandible were normal. Therefore, we recommend that denwas not the cause of the numbness in the region tists obtain comprehensive medical and dental innervated by the mental nerve and perform histories for patients who have numbness in the endodontic therapy without success. Signs of siglips, chin, gingiva and teeth. In some cases, after nificant bone lesions may not be present or not taking these histories and making functional fully noticed on radiographs, as in the two cases inquiries, dentists may suspect that a patient has we reported. Therefore, to prevent this type of an unknown primary cancer if clinical findings mistake, dentists need to be aware of the clinical such as cachexia, fever and fatigue are present. manifestations of NCS. Dentists need to rule out the presence of other Occasionally, patients with NCS may complain causes of NCS such as odontogenic factors (for of paresthesia and pain in the gingiva and example, dental infection, facial trauma and teeth.1-5 Touch and pain sensation tests with a osteomyelitis) and systemic factors (for example, small brush and a safety pin, respectively, should sickle cell anemia, diabetes mellitus and HIV JADA, Vol. 140
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infection) by taking medical and dental histories and obtaining panoramic radiographs.1 Proper treatment of lesions other than malignant tumors should resolve numbness due to the lesions. In particular, dentists should perform endodontic and periodontal therapies for odontogenic lesions. However, when the cause of numbness is not apparent, dentists should obtain CT images of the mandible. Therefore, we recommend that dentists always obtain CT images in patients who have known cancers and numbness in the mental region and lips. If the CT findings are negative, NCS may be due to compression of the intracranial trigeminal nerve root by a local metastatic deposit or metastasis to the meninges in the area. Lossos and Siegal7,8 have shown that obtaining CT images of the brain, base of the skull and mandible and conducting a cytological analysis of the cerebrospinal fluid led to a diagnosis of NCS in 89 percent of patients with NCS and known malignancy. On the basis of our two case reports, our experience and the reports in
the literature, we advocate that dentists obtain CT images of the mandible in patients who have the clinical manifestations of NCS and are at high risk of developing cancer on the basis of their ages, habits and other risk factors, even if they are not known to have cancer. CONCLUSIONS
When patients have the clinical manifestations of NCS and a diagnosis of cancer, dentists need to be aware of the criteria used to judge whether the cancer has gotten worse. For example, in cases involving prostate cancer, dentists should evaluate the patient’s PSA level, and, in cases involving multiple myeloma, dentists should assess blood test results. In the first case we reported, we could not obtain the patient’s PSA level data, but the value would have been more than 4 nanograms per deciliter, the PSA value that indicates that cancer is present. In the second case, beta2 monoclonal globulin protein, total protein, γ-globulin, immunoglobulin G, blood urea nitrogen and creatinine levels were high. Deterioration in the patient’s multiple myeloma would have been documented by the results of blood tests performed at the hospital with the hematology service. ■ Disclosure. None of the authors reported any disclosures. This study was supported in part by a grant-in-aid for scientific research from the Ministry of Education, Science, Sports and Culture of Japan and a grant-in-aid for scientific research from the president of Kyushu Dental College to Dr. Morimoto. 1. Smith SF, Blackman G, Hopper C. Numb chin syndrome: a nonmetastatic neurological manifestation of malignancy. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008;105(3):e53-e56. 2. 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(1):71-79. 3. López-Jornet P. Mental nerve neuropathy as initial symptom of cancer. N Y State Dent J 2007;73(6):36-37. 4. Kuklok KB, Burton RG, Wilhelm ML. Numb chin syndrome leading to a diagnosis of acute lymphoblastic leukaemia: report of a case. J Oral Maxillofac Surg 1997;55(12):1483-1485. 5. Hiraki A Nakamura S, Abe K, et al. Numb chin syndrome as an initial symptom of acute lymphocytic leukemia: report of three cases. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1997;83(5): 555-561. 6. Dotson RM. Clinical neurophysiology laboratory tests to assess the nociceptive system in humans. J Clin Neurophysiol 1997;14(1):32-45. 7. Lossos A, Siegal T. Case 27-1994: the numb chin syndrome. N Engl J Med 1994;331(21):1460. 8. Lossos A, Siegal T. Numb chin syndrome in cancer patients: etiology, response to treatment, and prognostic significance. Neurology 1992;42(6):1181-1184.
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May 2009
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C A SE REPOR T
The importance of clinical features and computed tomographic findings in numb chin syndrome A report of two cases Izumi Yoshioka, DDS, PhD; Shunji Shiiba, DDS, PhD; Tatsurou Tanaka, DDS, PhD; Takeshi Nishikawa, DDS; Eiji Sakamoto, DDS, PhD; Shinji Kito, DDS, PhD; Masafumi Oda, DDS; Nao Wakasugi-Sato, DDS, PhD; Shinobu Matsumoto-Takeda, DDS, PhD; Shigeyuki Kagawa, DDS; Osamu Nakanishi, DDS, PhD; Kazuhiro Tominaga, DDS, PhD; Yasuhiro Morimoto, DDS, PhD
umb chin syndrome (NCS) is a rare condition that is the result of mental nerve neuropathy, which is a sensory neuropathy. The symptoms of NCS include numbness of the skin of the lips and chin, the gingiva and the teeth, most often due to metastasis of a primary malignancy of the mandible.1-5 Other causes of NCS are dental infection, facial trauma, osteomyelitis, sickle cell anemia, diabetes mellitus and HIV infection. There are numerous reports of NCS in the medical literature and only a few in the dental literature.1,3-5 Most dentists are not aware of NCS and its clinical manifestations. In patients with NCS and accompanying tooth pain, dentists may unknowingly perform unnecessary and useless endodontic therapy
N
ABSTRACT Background. Dentists need to be aware of the relationship between malignancies and paresthesia or complete loss of sensation in a jaw segment. In particular, dentists should be aware of numb chin syndrome (NCS) and its clinical manifestations, as well as the limitations of using panoramic radiographs to detect the causative malignancy. Case Descriptions. The authors report two cases of paresthesia in the mental region. No lesions were readily apparent on the patients’ panoramic radiographs. To exclude the presence of disease in the mandible that could have been responsible for the NCS, the authors obtained computed tomographic (CT) images. They identified metastases to the mandible from primary malignant tumors elsewhere in the body. Clinical Implications. To prevent misdiagnosis of NCS, dentists need to be aware of the clinical manifestations of NCS, the need for CT imaging, the shortcomings of panoramic radiographs and the value of obtaining detailed and accurate medical and dental histories from patients. Key Words. Numb chin syndrome; paresthesia; panoramic radiograph; metastasis; malignancy; jaws. JADA 2009;140(5):550-554.
Dr. Yoshioka is an associate professor, Department of Oral and Maxillofacial Surgery, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Shiiba is an assistant professor, Department of Control of Physical Functions, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Tanaka is an assistant professor, Department of Oral Diagnostic Science, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Nishikawa is an instructor, Department of Oral and Maxillofacial Surgery, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Sakamoto is an assistant professor, Department of Control of Physical Functions, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Kito is an assistant professor, Department of Oral Diagnostic Science, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Oda is a postgraduate student, Department of Oral Diagnostic Science, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Wakasugi-Sato is an assistant professor, Department of Oral Diagnostic Science, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Matsumoto-Takeda is an assistant professor, Department of Oral Diagnostic Science, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Kagawa is an intern, Department of Oral Diagnostic Science, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Nakanishi is a professor and the chairman, Department of Control of Physical Functions, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Tominaga is a professor and the chairman, Department of Oral and Maxillofacial Surgery, Kyushu Dental College, Kitakyushu, Fukuoka, Japan. Dr. Morimoto is a professor and the chairman, Department of Oral Diagnostic Science, Kyushu Dental College, 2-6-1 Manazuru, Kokura-kita, Kitakyushu, Fukuoka 803-8580, Japan, e-mail “[email protected]”. Address reprint requests to Dr. Morimoto.
550
JADA, Vol. 140
http://jada.ada.org
May 2009
Copyright © 2009 American Dental Association. All rights reserved. Reprinted by permission.
C L I N I C A L P R A C T I C E CASE REPORT
to treat the painful teeth. Dentists should be able to recognize the clinical manifestations of NCS, such as paresthesia and gingival or tooth pain. They also should be aware that NCS can be the result of metastasis of a primary tumor to the mandible that cannot be identified on panoramic radiographs but that can be identified on computed tomographic (CT) images. Thus, CT images are an important tool that can be used to assess patients who exhibit the clinical manifestations of NCS. We present two cases that highlight the need for CT imaging, the shortcomings of panoramic radiographs and the need for dentists to investigate the status of a patient’s cancer and the clinical manifestations of NCS. CASE REPORTS
Case 1. In early 2003, a private practitioner referred a 69-year-old man with chief complaints of paresthesia and pain in the left mental region to our dental hospital at Kyushu Dental College, Kitakyushu, Fukuoka, Japan. In 2000, the patient’s prostate cancer had been diagnosed and treated with local excision and hormone treatment. He subsequently was seen in the urology department of another hospital and was prescribed the chemotherapeutic agent estramustine to treat his prostate cancer. The patient also reported that he had received a diagnosis of having no particular brain pathology after having undergone brain surgery in 2007. In the patient’s initial 2003 visit to the dental hospital, he reported that paresthesia and pain began about two weeks earlier and the severity had been increasing. With respect to the degree of the paresthesia, the patient gave a score of 3 for both touch (as assessed by using a small brush) and pain (as assessed by using a safety pin stick) sensation in the left mental region and a score of 10 for both on the unaffected right side. We used 10-point scales to assess touch and pain in which in which 1 represented no pain and no feeling of touch, respectively, and 10 represented the most pain and the most touch sensation, respectively. Lip movement and taste sensation were normal. We suspected that the patient had NCS and obtained a panoramic radiograph. On the radiograph, we noted generalized horizontal bone loss and obvious bony defects that suggested severe periodontal disease (Figure 1A). Consequently, the uniform destruction and widening of the periodontal ligament space, the periapical radi-
olucency with poorly defined borders and the thinning of the lower cortical border of the mandible could have been overlooked easily because the findings were unclear or had been dismissed as further evidence of periodontal disease instead of suggesting that malignant disease is present (Figure 1A). To exclude the presence of bone lesions in the mandible that could have been responsible for NCS, the patient underwent CT scanning (Figures 1B and 1C). On the CT images, we saw the typical findings of metastasis to the mandible from prostate cancer. These findings included osteoblastic changes in the left side of the mandible (Figure 1B) and destruction of cortical bone (Figure 1C). The patient underwent technetium Tc 99m methylene diphosphonate nuclear medicine bone scanning at about the same time. The results showed an increased uptake of technetium Tc 99m methylene diphosphonate in the left side of the mandible, a right rib and the spine (Figure 1D). We biopsied the lesions in the left side of the mandible and, on the basis of the results, made a diagnosis of prostate cancer (which was a recurrence of the prostate cancer the patient had had in 2000). The patient’s prostate specific antigen (PSA) level could not be obtained in our hospital. He was treated with chemotherapy and hormone treatment at another hospital, and he died a year later. Case 2. In early 2008, a 79-year-old woman with a chief complaint of paresthesia of the left mental region—including the lips but without pain—visited our dental hospital. The paresthesia had begun about one week earlier and had been increasing. With respect to the degree of paresthesia, the electric detection threshold, as determined by means of electric stimulators, was twice as high for the left mental region as it was for the right. Lip movement and taste sensation were normal. The patient had undergone chemotherapy for multiple myeloma in 2000. On the basis of the patient’s medical and dental histories and our clinical findings, we suspected that she had NCS. We obtained a panoramic radiograph that showed asymmetry in the radiographic appearance of the left and the right sides of the mandible and thinning of the lower cortical border of the mandible (Figure 2A, page ABBREVIATION KEY. CT: Computed tomographic. NCS: Numb chin syndrome. PSA: Prostate specific antigen. JADA, Vol. 140
http://jada.ada.org
Copyright © 2009 American Dental Association. All rights reserved. Reprinted by permission.
May 2009
551
C L I N I C A L P R A C T I C E CASE REPORT
A
B
C
D
Figure 1. Case 1. Imaging in a 69-year-old man with paresthesia and pain in the left mental region. A. Panoramic radiograph showing features suggesting generalized periodontal disease, especially in relation to the mandibular left molars. The widening of the periodontal ligament, a periapical radiolucency with poorly defined borders and thinning of the lower cortical border of the mandible (suggestive of a malignancy) can be overlooked easily. B. Axial computed tomographic (CT) image with a soft-tissue window showing osteoblastic changes (arrowhead). C. Axial CT image with a bone window showing destruction of the cortical bone (white arrows). D. A technetium Tc 99m methylene diphosphonate nuclear medicine bone scan image showing increased uptake of technetium Tc 99m methylene diphosphonate in the left side of the mandible (black arrow), a right rib (black arrowhead) and the spine (white arrow).
553). These findings on the panoramic radiograph could have been overlooked easily because the findings were unclear. To exclude the possibility that bone lesions in the mandible could be responsible for NCS, the patient underwent CT scanning (Figures 2B and 2C). We saw the typical findings of metastasis to the mandible from multiple myeloma on the CT images, as well as bilateral destruction of the cortical bone in the mandible (Figure 2C). Subsequently, the patient was referred to another hospital that had a hematology service, in which blood tests were performed. The results of the tests showed that her beta2 monoclonal globulin level was high (23.3 milligrams per liter), total protein level was relatively high (8.9 grams per deciliter), gamma globulin level was high (34.5 percent), and immunoglobulin G level was high (3,862 mg/dL). Her blood urea nitrogen level was high (33.3 mg/dL), and her creatinine level 552
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was high (2.24 mg/dL). The results of a test to detect Schilling leukemia (acute monocytic leukemia) showed plasma cells with dysplasia. The patient has been undergoing chemotherapy and follow-up treatment for multiple myeloma. DISCUSSION
NCS is a rare syndrome that manifests as numbness in the regions innervated by the mental nerve, including the lip, chin, gingiva and teeth. It most often is due to metastasis of primary malignancy to the mandible.1-5 The main cause of NCS includes perineural spread of metastatic disease or compression of nerve tissue by a tumor. Other causes are dental infection, facial trauma, osteomyelitis, sickle cell anemia, diabetes mellitus and HIV infection. No discernible pattern and no male or female preponderance has been found in NCS.1 Smith and colleagues1 reported that a substantial number of NCS cases have been reported in the
May 2009
Copyright © 2009 American Dental Association. All rights reserved. Reprinted by permission.
C L I N I C A L P R A C T I C E CASE REPORT
be performed to diagnose numbness manifesting as paresthesia in the mental region. The presence of numbness, manifesting as paresthesia, can be evaluated easily by comparing the scores of the touch and pain tests for the right and left sides. If there is a significant difference between the scores for A touch test, pain test or both for the two sides, a diagnosis of NCS should be suspected. Then a patient’s report of abnormal sensation should be considered. In the first case we reported, we evaluated paresthesia on the basis of the patient’s medical and dental histories and the sensory examination. In the second case, we determined the patient’s B C electric detection threshold, which is useful for Figure 2. Case 2. Imaging in a 79-year-old woman with paresthesia in the left mental region. A. Panoramic radiograph showing features of bone destruction that could be overlooked readily or assessing the presence of dismissed as a variation of normal: a large radiolucency in the left side of the mandible, not seen on paresthesia.6 However, the right side, and thinning of the lower cortical border of the mandible. B . Axial computed tomographic (CT) image with a soft-tissue window showing soft-tissue opaque structures (black arrows) specific tools such as bilaterally as typical findings of metastasis to the mandible from multiple myeloma. C . Axial CT image electric stimulators are with a bone window showing bilateral destruction of cortical bone and sponginess (black arrows). needed to determine the medical literature but only a few have been patient’s electric detection threshold. Therefore, reported in the dental literature.1,3-5 Most dentists we advocate that dentists conduct touch and pain are unaware of NCS and its clinical manifestasensation tests to diagnose numbness in the tions. Dentists who are unaware of NCS and have mental region. Usually, only the sensory innervaa patient who has a complaint of paresthesia in tion is affected, since the inferior alveolar nerve the mental region may obtain panoramic radihas no motor fibers. Since motor function is ographs, other dental radiographs or both. Howintact, movement of the lower lip is possible in ever, in cases similar to those we reported, if no cases of NCS. In the two cases we reported, the specific abnormalities are seen on the radipatients’ lip movements and taste sensations ographs, dentists may conclude that the mandible were normal. Therefore, we recommend that denwas not the cause of the numbness in the region tists obtain comprehensive medical and dental innervated by the mental nerve and perform histories for patients who have numbness in the endodontic therapy without success. Signs of siglips, chin, gingiva and teeth. In some cases, after nificant bone lesions may not be present or not taking these histories and making functional fully noticed on radiographs, as in the two cases inquiries, dentists may suspect that a patient has we reported. Therefore, to prevent this type of an unknown primary cancer if clinical findings mistake, dentists need to be aware of the clinical such as cachexia, fever and fatigue are present. manifestations of NCS. Dentists need to rule out the presence of other Occasionally, patients with NCS may complain causes of NCS such as odontogenic factors (for of paresthesia and pain in the gingiva and example, dental infection, facial trauma and teeth.1-5 Touch and pain sensation tests with a osteomyelitis) and systemic factors (for example, small brush and a safety pin, respectively, should sickle cell anemia, diabetes mellitus and HIV JADA, Vol. 140
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infection) by taking medical and dental histories and obtaining panoramic radiographs.1 Proper treatment of lesions other than malignant tumors should resolve numbness due to the lesions. In particular, dentists should perform endodontic and periodontal therapies for odontogenic lesions. However, when the cause of numbness is not apparent, dentists should obtain CT images of the mandible. Therefore, we recommend that dentists always obtain CT images in patients who have known cancers and numbness in the mental region and lips. If the CT findings are negative, NCS may be due to compression of the intracranial trigeminal nerve root by a local metastatic deposit or metastasis to the meninges in the area. Lossos and Siegal7,8 have shown that obtaining CT images of the brain, base of the skull and mandible and conducting a cytological analysis of the cerebrospinal fluid led to a diagnosis of NCS in 89 percent of patients with NCS and known malignancy. On the basis of our two case reports, our experience and the reports in
the literature, we advocate that dentists obtain CT images of the mandible in patients who have the clinical manifestations of NCS and are at high risk of developing cancer on the basis of their ages, habits and other risk factors, even if they are not known to have cancer. CONCLUSIONS
When patients have the clinical manifestations of NCS and a diagnosis of cancer, dentists need to be aware of the criteria used to judge whether the cancer has gotten worse. For example, in cases involving prostate cancer, dentists should evaluate the patient’s PSA level, and, in cases involving multiple myeloma, dentists should assess blood test results. In the first case we reported, we could not obtain the patient’s PSA level data, but the value would have been more than 4 nanograms per deciliter, the PSA value that indicates that cancer is present. In the second case, beta2 monoclonal globulin protein, total protein, γ-globulin, immunoglobulin G, blood urea nitrogen and creatinine levels were high. Deterioration in the patient’s multiple myeloma would have been documented by the results of blood tests performed at the hospital with the hematology service. ■ Disclosure. None of the authors reported any disclosures. This study was supported in part by a grant-in-aid for scientific research from the Ministry of Education, Science, Sports and Culture of Japan and a grant-in-aid for scientific research from the president of Kyushu Dental College to Dr. Morimoto. 1. Smith SF, Blackman G, Hopper C. Numb chin syndrome: a nonmetastatic neurological manifestation of malignancy. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2008;105(3):e53-e56. 2. 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(1):71-79. 3. López-Jornet P. Mental nerve neuropathy as initial symptom of cancer. N Y State Dent J 2007;73(6):36-37. 4. Kuklok KB, Burton RG, Wilhelm ML. Numb chin syndrome leading to a diagnosis of acute lymphoblastic leukaemia: report of a case. J Oral Maxillofac Surg 1997;55(12):1483-1485. 5. Hiraki A Nakamura S, Abe K, et al. Numb chin syndrome as an initial symptom of acute lymphocytic leukemia: report of three cases. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1997;83(5): 555-561. 6. Dotson RM. Clinical neurophysiology laboratory tests to assess the nociceptive system in humans. J Clin Neurophysiol 1997;14(1):32-45. 7. Lossos A, Siegal T. Case 27-1994: the numb chin syndrome. N Engl J Med 1994;331(21):1460. 8. Lossos A, Siegal T. Numb chin syndrome in cancer patients: etiology, response to treatment, and prognostic significance. Neurology 1992;42(6):1181-1184.
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