|Year : 2015 | Volume
| Issue : 2 | Page : 323-325
Numb chin syndrome
Guruprasad S Pujar, Basavaraj F Banakar, Amita Bhargava, Shubhkaran Khichar
Department of Neurology, Dr. S. N. Medical College, Jodhpur, Rajasthan, India
|Date of Web Publication||16-Dec-2015|
Guruprasad S Pujar
Department of Neurology, M G Hospital, Jodhpur - 342 001, Rajasthan
Source of Support: None, Conflict of Interest: None
Numb chin syndrome (NCS), also known as mental neuropathy, is a sensory neuropathy characterized by numbness involving the distribution of the mental nerve and is an uncommon, but underappreciated neuropathy. The clinical importance lies in its frequent association with malignancies, particularly lymphoma and breast cancer. We report a 30-year-old patient who presented with bilateral numb chin for few days for which no cause was found. Over 3 weeks, he developed systemic symptoms and neck swelling. Investigations revealed low platelet count, raised erythrocyte sedimentation rate, alkaline phosphatase, and lactate dehydrogenase. Biopsy of the swelling and Bone marrow confirmed Burkitt's lymphoma. Imaging studies confirmed intracranial and hepatic metastasis. Within few days of initiation of therapy, patient succumbed to the disease. Here, we would like to emphasize that all clinicians should be aware of this entity and investigate thoroughly to rule out underlying malignancies as delay in diagnosis leads to the adverse outcome.
Keywords: Burkitt′s lymphoma, mental nerve, numb chin syndrome
|How to cite this article:|
Pujar GS, Banakar BF, Bhargava A, Khichar S. Numb chin syndrome. Arch Med Health Sci 2015;3:323-5
| Introduction|| |
Numb chin syndrome (NCS), also called mental neuropathy, is a sensory neuropathy characterized by numbness involving the distribution of the mental nerve and is an uncommon, but underappreciated neuropathy.  The clinical importance of this syndrome lies in its frequent association with malignancies, particularly lymphoma and breast cancer.  Most cases of NCS occur in the setting of known cancer, but they may occasionally be the presenting symptom of malignancy.  In patients with a history of cancer, NCS often indicates disease recurrence or progression. NCS of neoplastic origin is usually unilateral, but rarely bilateral presentations can also occur.  Till now, only nine such cases had been reported; probably, this is the tenth case with bilateral NCS preceding the diagnosis of malignancy.
| Case Report|| |
A 30-year-old right-handed unemployed Hindu adult male came to us with complaints of numbness of the chin of 1-month duration, which was continuous without any associated pain. He consulted many physicians and a dentist, but no local or dental cause was found, and was treated symptomatically without much relief. Over a period of 20 days, he developed myalgia, loss of appetite, excessive sweating. Within 4 days of these symptoms, patient noticed painful swelling over the upper part of the neck, which increased in size rapidly. Two days prior to admission at our center, he developed diplopia for distant objects, slurring of speech, and dysphagia for solid foods.
On examination, vitals were stable. A swelling was present in left upper part of the neck measuring 5 cm × 6 cm, immobile, tender, firm with a smooth surface. On systemic examination, patient was conscious, cooperative with bilateral 6 th , 12 th cranial nerve palsies and hypoesthesia over mental area. Rest of neurological and systemic examination was normal.
On investigating following abnormalities were detected. Raised erythrocyte sedimentation rate-80 mm at 1 st h (0-15 mm/h), low platelet count- 72,000/cmm (normal 165-415 × 10 3 /cmm), raised alkaline phosphatase - 412 u/l (33-96 u/l), raised lactate dehydrogenase-1875u/l (115-221 u/l), negative for serology including HIV, hepatitis B surface antigen, hepatitis C virus. Cerebrospinal fluid analysis showed low glucose 24 mg/dl (40-70 mg/dl), high protein-112 mg/dl (15-50 mg/dl) with lymphocytic pleocytosis-26 cell/mm 3 (0-5/mm 3 ). Biopsy of neck swelling showed high-grade non-Hodgkin's lymphoma with CD-20 pan-B and mib-1 positive confirming Burkitt's lymphoma. Bone marrow biopsy revealed 80% blast cells suggesting marrow infiltration. Magnetic resonance imaging (MRI) of neck and mandible showed circumscribed lymphnode mass in left upper and middle internal jugular group with altered marrow signal intensity in mandible [Figure 1]. MRI brain with contrast showed diffuse bilateral symmetric pachymeningitis [Figure 2] and [Figure 3]. Computed tomography (CT) abdomen showed hepatomegaly with small multiple hypodensities suggestive of metastasis.
|Figure 1: MRI neck showing circumscribed lymphnode mass with altered signal intensity in mandible|
Click here to view
|Figure 2: MRI brain with contrast(axial) showing diffuse bilateral symmetric pachymeningeal enhancement|
Click here to view
|Figure 3: MRI brain with contrast(coronal) showing diffuse bilateral symmetric pachymeningeal enhancement|
Click here to view
With these investigations, patient was diagnosed as a case of non-Hodgkin's lymphoma grade 4-Burkitt's type [Figure 4] and was referred to the oncology unit. After 10 days of initiation of treatment, patient succumbed.
| Discussion|| |
Numb chin syndrome denotes mental neuropathy with numbness of the chin and lower lip. Although the earliest descriptions of this entity could be quoted to Charles Bell's monograph, "The nervous system of the human body" published in 1830, the term "syndrome of numb chin" was first coined by Calverley and Mohnac, in1963.  This syndrome has since been reported in various diseases and malignancies as listed in [Table 1]. 
Symptoms of NCS typically include unilateral numbness of the skin of the chin, lip, and occasionally, the gingiva.  Numbness is usually unilateral, but rarely, it can be bilateral as seen in our case. Hypoesthesia is usually present over the chin, lip, and gingiva, but motor function of the lower face is intact.  If metastatic malignancy is present, patients may have systemic symptoms in addition to symptoms related to the primary tumor. However, symptoms of NCS may precede other symptoms of malignancy. In our case, bilateral numbness of the chin preceded systemic symptoms.
The mandibular nerve can be affected either intra- or extra-cranially.  In extracranial involvement, the most common etiology is involvement of the inferior alveolar nerve within the mandible. This results from nerve compression by osseous involvement of the mandible or tumor infiltration along the nerve sheath. In intracranial involvement, the pathogenesis of NCS can be either involvement of the trigeminal nerve root by meningeal carcinomatosis or direct infiltration of malignant cells into the trigeminal nerve. Cases of intracranial involvement are associated with other CNS signs, like cranial neuropathies, headache or vomiting. In our case, patient presented with NCS and subsequently developed bilateral 6 th and 12 th cranial nerve palsies, which suggested intracranial involvement.
The diagnosis of NCS is largely clinical. However, various radiographic studies are helpful to confirm the diagnosis, such as panoramic jaw radiography, CT scanning, MRI, and nuclear bone scintigraphy.
Computed tomography or MRI of the brain and skull base may reveal evidence of a mass lesion, parenchymal brain metastases, or meningeal invasion by tumor in the area of the root of the mandibular division of the trigeminal nerve. MRI of head and neck in our case revealed lymphnode mass in neck and pachymeningitis which suggested intracranial involvement. CT thorax and abdomen revealed liver metastasis.
Cerebrospinal fluid analysis may also be necessary to exclude carcinomatous meningitis if imaging studies fail to reveal an anatomic lesion. Our patient had raised protein, low glucose with lymphocytic pleocytosis without atypical cells.
Bilateral numbness of the lower lip and chin is extremely unusual.  Our search of the literature revealed case report by Sasaki et al. which mentions only 23 cases of bilateral NCS associated with malignancy, in which 16 were with hematologic, and 7 with solid malignancies. The onset of bilateral NCS preceded the diagnosis of the primary tumor in 9 out of the 23 cases.  In the remaining 14 cases, the primary tumor had already been diagnosed. This signifies hematologic malignancies infiltrate the CNS more readily than solid malignancies, possibly accounting for the high proportion of bilateral NCS.  As our patient had Burkitt's lymphoma, the most rapidly progressive human tumor,  the delay in initiating therapy adversely affected the outcome.
| Conclusion|| |
Numb chin syndrome, though a benign symptom could be a harbinger of serious illness. It should be regarded as being due to malignancy until proven otherwise. If the patient presents with bilateral NCS rule out hematological malignancies.
| References|| |
Marinella MA. Metastatic large cell lung cancer presenting with numb chin syndrome. Respir Med 1997;91:235-6.
Laurencet FM, Anchisi S, Tullen E, Dietrich PY. Mental neuropathy: Report of five cases and review of the literature. Crit Rev Oncol Hematol 2000;34:71-9.
Eisenbud L, Sciubba J, Mir R, Sachs SA. Oral presentations in non-Hodgkin's lymphoma: A review of thirty-one cases. Part I. Data analysis. Oral Surg Oral Med Oral Pathol 1983;56:151-6.
Lossos A, Siegal T. Numb chin syndrome in cancer patients: Etiology, response to treatment, and prognostic significance. Neurology 1992;42:1181-4.
Furukawa T. Historical neurology: Charles Bell's description of numb chin syndrome. Neurology 1988;38:331.
Marinella MA. Numb chin syndrome: A subtle clue to possible serious illness. Hosp Physician 2000;36:54-6.
Sasaki M, Yamazaki H, Aoki T, Ota Y, Sekiya R, Kaneko A. Bilateral numb chin syndrome leading to a diagnosis of Burkitt's cell acute lymphocytic leukemia: A case report and literature review. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011;111:e11-6.
Fauci AS, Kasper DL, Longo DL, Braunwald E, Hauser SL, Jameson JL, et al
. Harrison's Principles of Internal Medicine. 17 th
ed. New York: McGraw Hill; 2008. p. 696-7.
[Figure 1], [Figure 2], [Figure 3], [Figure 4]