ENDODOMICS Editor: Samuel Seltzer

Mandibular nerve neuropathy in sickle cell disease Local factors

Garry Gregory, FRACDS, FRCS(Ed),” and Adebayo Olujohungbe, MRCP,b London, England EASTMAN DENTAL HOSPITAL AND THE ROYAL LONDON HOSPITAL, WfIITECfiAPEL

An instance of permanent neuropathy that affected the mandibular nerve after a vaso-occlusive crisis in a patient

with homozygous sickle cell disease and C6PD deficiency. A local factor of molar periapical inflammation may have provoked

this phenomenon. (ORAL SJRC ORAL MED ORAL PAMOL 1994;7766-9)

The sickle hemoglobin molecule undergoes intracel- lular polymerization when oxygen saturation de- creases. Below 85% saturation, there is a sharp rise in sickle blood viscosity,’ as flexible biconcave disks are transformed into nonflexible sickle cells. Vaso-occlu- sive phenomena mainly occur in the microcirculation when continuous flow is interrupted. Sickle cells have an increased adherence to capillary endothelial cells shown in both static and dynamic experimental mod- els.2 Local conditions of chronic inflammation with reduced blood flow would seem to promote the onset of local vaso-occlusive ischemic necrosis.

CASE REPORT A 27-year-old Nigerian physician underwent one-stage

endodontic therapy for the right mandibular second molar in February 199 1 (Fig. 1). The tooth had been symptomatic with thermal sensitivity, but a preoperative radiograph did not show evidence of periapical involvement. He had a medical history of homozygous sickle-cell disease and glu- case-6-phophate dehydrogenase deficiency and had been admitted previously with aplastic and vaso-occlusive crises.

After this treatment, he experienced occasional pain from that tooth but did not seek further consultation. In early March 199 1, he was admitted with a typical sickle-cell cri- sis (Hb 3gm/dl, normal = 13 to 18 gm/dl). He had severe

BLecturer, Honorary Senior Registrar, Oral and Maxillofacial Unit, Eastman Dental Hospital.

bLecturer, Honorary Senior Registrar, Haematology Unit, The Royal London Hospital, Whitechapel Copyright @ 1994 by Mosby-Year Beck, In c.

0030-4220/93/$1.00 + .I0 7/15/50610

bone pains in the legs, the back, and right elbow indicating bone infarcts. After an exchange transfusion he recovered and left the hospital to resume his internship. The recently treated molar continued to cause occasional pain with chewing, and he noticed the sudden onset of paresthesia of the lower lip in early April 199 1. There was progressive re- duction in pain as anesthesia of the right lower lip supet- vened, and he came to the Oral Surgery service on May 7, 1991.

General examination He had healthy appearance with a lean body shape typ-

ical of homozygous sickle state.

Special examination His lower right molar teeth had slight percussion sensi-

tivity. He had anesthesia of lower lip in area of right men- tal nerve. His oral mucosa appeared healthy.

Investigations A petiapical radiograph (Figs. 2 and 3) displayed an ade-

quate molar root canal filling and interproximal stepladder trabeculation and faint lamina dura consistent with HbSS. Dynamic radionuclide bone scan (Fig. 4) confirmed a slightly increased tracer uptake in the right mandibular molar region indicative of infarction. A CT scan (Fig. 5) showed loss of normal cortical condensation around the right mental canal, although it was present on the left side.3

Treatment With no history or findings suggestive of alternative dis-

ease causing mononeuropathy, a presumptive diagnosis of segmental nerve infarction related to sickle-cell crisis was made. The recent endodontic episode was thought to have contributed to local inflammatory change, and there was no

ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY Volume 77, Number 1

Gregory and Olujohungbe 67

Fig. 1. One-stage endodontic treatment. Periapical radiographs show no preceding apical bone loss. Note proximity of mandibular canal.

Fig. 2. Periapical films from A June 1991 and B December 1991. Both show step ladder trabeculation of alveolar bone.

Fig. 3. Panoramic radiograph, June 1991.

sign of cement extrusion, which is a well-known cause of mandibular nerve dysfunction.

A course of augmentin and ibuprofen was prescribed in view of the continued local tenderness. Although the signs of inflammation soon resolved, he continued to have anes- thesia of the hemilip when reviewed 24 months later.

DISCUSSION Although “syndrome of the numb chin” arising de

novo is a likely manifestation of distant neoplasia,4 several similar mononeuropathies are reported in the setting of sickle-cell crisis although the normally rich

microvasculature of peripheral nerves makes this complication rare indeed.5 Recovery of nerve function has been delayed at least 18 months after sickle-cell infarction of the mandibular nerve. In contrast to other peripheral nerves, the mandibular nerve may be relatively vulnerable to microvascular infarction be- cause of its passage through a narrow boney canal in a similar way to the dental pulp when local inflam- mation occurs. Molar sepsis in otherwise normal pa- tients is occasionally associated with temporary man- dibular nerve dysfunction, and it is a significant symptom suggestive of osteomyelitis.

68 Gregory and Olujohungbe ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY Januarv 1994

Fig. 4. Bone scan shows slightly increased tracer uptake in right mandibular molar region suggestive of in- farcted bone.

Fig. 5. Computed tomography scan shows no evidence of alternative explanation for mandibular nerve neu- ropathy.

Patients with sickle-cell disease are immune-defi- cient because of autosplenectomy early in life and during crises when sickle-laden macrophages are un- available for normal duty. Also, their neutrophils have a complicated functional abnormality that af- fects adherence, migration, and bactericidal func- tion.6 Destructive osteomyelitis of the mandible is a well known complication of dental infection in sickle disease.7-9

Therefore to protect against complications relating to hypoxia, infection, or other causes of inflammation

in patients with sickle-cell disease undergoing dental treatment, an aggressively defensive treatment pro- tocol should be followed. Prophylactic antibiotics and anti-inflammatory medication should be used, and endodontic transgression of root apices should be avoided. The use of vasoconstrictor in local anesthetic is possibly questionable in homozygous patients with sickle-cell disease, whereas steroid use is associated with increased coagulability and immunosuppression but perhaps offset by reduction of inflammation.

Patients with diminished osseous vascularity after

ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY Volume 77, Number 1

irradiation or with rare dense bone disorders such as osteopetrosis and mature Paget’s disease, should be treated as an analogous group with a similar potential for iatrogenic vascular/infective complications.

We thank Mr. Richard Liversedge for permitting us to report this fascinating case.

REFERENCES

1. Chien S, Usami S, Bertles JF. Abnormal rheology of oxygen- ated blood in sickle cell anaemia. J Clin Investig 1970;49:623-4.

2. Smith BD, LaCelIe PL. Erythrocyte-endothelial cell adher- ence in sickle cell disorders. Blood: 1986;68:1050-4.

3. Royal JE, Harris VJ, Sansi PK. Facial bone infarcts in sickle- cell syndromes. Radiology 1988;169:529-31.

4. Friedlander AH, Genser L, Swordloff M. Mental nerve neu- ropathy: a complication of sickle cell crisis. ORAL SURG ORAL MED ORAL PATHOL 1980;49:15-7.

Gregory and Olujohungbe 69

5. Shields RW Jr, Harris JW, Clark M. Mononeuropathy in sickle cell anaemia: anatomical and pathophysiological basis for its rarity. Muscle Nerve 1991;14:370-4.

6. Falcao RP, Donadi EA. Infection and immunity in sickle cell disease. Rev Ass Med Brasil 1989;35:70-4.

7. Shroyer JV III, Lew D, Abreo F, Unhold GP. Osteomyelitis of the mandible as a result of sickle cell disease: report and lit- erature review. ORAL SURG ORAL MED ORAL PATHOL 1991;72:25-8.

8. Konotey-Ahulu FL Ischaemic neuropraxia of the mental nerve. Lancet 1972;2:388-9.

9. Patton LL, Brahim JS, Travis WD. Mandibular osteomyelitis in a patient with sickle cell anaemia: report of a case. J Am Dent Assoc 1990;121:602-4.

Reprint requests:

Garry Gregory, FRACDS, FRCS(Ed) 81 Hadley Rd. Barnet EN5 5QU United Kingdom