Lingual nerve damage due to inferior alveolar nerve blocks: a possible explanation.
BACKGROUND
An explanation for the predominance of injuries to lingual nerves over those to inferior alveolar nerves as a result of inferior alveolar nerve blocks may be due to the nerves' fascicular pattern. A unifascicular nerve may be injured more easily than a multifascicular nerve.


METHODS
The authors unilaterally dissected lingual and inferior alveolar nerves from 12 cadavers. They cut the specimens 2 millimeters above the lingula for both the lingual nerve and inferior alveolar nerve and opposite the site of the middle of the third molar for the lingual nerve, and they counted the number of fascicles at each site.


RESULTS
For the lingual nerve at the lingula, the mean number of fascicles was three (range, one to eight). Four of the 12 nerves (33 percent) were unifascicular at this point. Opposite the third molar, the lingual nerve had a mean of 20 fascicles (range, six to 39). In every case, there were more fascicles in the third molar region than above the lingula in the same nerve. At the lingula, the inferior alveolar nerve had a mean of 7.2 fascicles (range, three to 14).


CONCLUSIONS
This study may explain the observation that when an inferior alveolar nerve block causes permanent nerve impairment, the lingual nerve is affected about 70 percent of the time and the inferior alveolar nerve is affected only 30 percent of the time. In 33 percent of cases, the lingual nerve had only one fascicle at the lingula; a unifascicular nerve may be injured more easily than a multifascicular one.


CONCLUSIONS
There is no known way to avoid the remote possibility of nerve damage resulting from an inferior alveolar nerve block. The lingual nerve may be predominantly affected because of its fascicular pattern.
Pogrel
M Anthony
MA
Department of Oral and Maxillofacial Surgery, University of California, San Francisco 94143-0440, USA. map@itsa.ucsf.edu
Schmidt
B L
BL
Sambajon
V
V
Jordan
R C K
RC
D000766:Anesthesia, Dental / Q000009:adverse effects*; D002102:Cadaver; D006801:Humans; D008036:Lingual Nerve / Q000033:anatomy & histology*; D061222:Lingual Nerve Injuries; D008334:Mandible / Q000294:innervation; D008340:Mandibular Nerve / Q000033:anatomy & histology; D008964:Molar, Third / Q000294:innervation; D009407:Nerve Block / Q000009:adverse effects*; D009412:Nerve Fibers / Q000648:ultrastructure