title: Iatrogenic damage to the mandibular nerves as assessed by the masseter inhibitory reflex.
abstract: Iatrogenic injury of the inferior alveolar or lingual nerves frequently leads to legal actions for damage and compensation for personal suffering. The masseter inhibitory reflex (MIR) is the most used neurophysiological tool for the functional assessment of the trigeminal mandibular division. Aiming at measuring the MIR sensitivity and specificity, we recorded this reflex after mental and tongue stimulations in a controlled, blinded study in 160 consecutive patients with sensory disturbances following dental procedures. The MIR latency was longer on the affected than the contralateral side (P < 0.0001). The overall specificity and sensitivity were 99 and 51%. Our findings indicate that MIR testing, showing an almost absolute specificity, reliably demonstrates nerve damage beyond doubt, whereas the relatively low sensitivity makes the finding of a normal MIR by no means sufficient to exclude nerve damage. Probably, the dysfunction of a small number of nerve fibres, insufficient to produce a MIR abnormality, may still engender important sensory disturbances. We propose that MIR testing, when used for legal purposes, be considered reliable in one direction only, i.e. abnormality does prove nerve damage, normality does not disprove it.
authors.affiliation: Department of Neurology and Psychiatry, Sapienza University, Viale Università 30, 00185 Rome, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Biasiotta
authors.forename: P
authors.initials: P
authors.lastname: Cascone
authors.forename: R
authors.initials: R
authors.lastname: Cecchi
authors.forename: G
authors.initials: G
authors.lastname: Cruccu
authors.forename: G
authors.initials: G
authors.lastname: Iannetti
authors.forename: A
authors.initials: A
authors.lastname: Mariani
authors.forename: A
authors.initials: A
authors.lastname: Spota
authors.forename: A
authors.initials: A
authors.lastname: Truini
mesh_terms: D000328:Adult; D003814:Dentistry, Operative / Q000331:legislation & jurisprudence; D004576:Electromyography / Q000379:methods*; D005260:Female; D006801:Humans; D007049:Iatrogenic Disease; D008297:Male; D008406:Masseter Muscle / Q000294:innervation; D008875:Middle Aged; D019647:Oral Surgical Procedures / Q000009:adverse effects* / Q000331:legislation & jurisprudence; D010523:Peripheral Nervous System Diseases / Q000175:diagnosis / Q000209:etiology; D012018:Reflex / Q000502:physiology*; D012680:Sensitivity and Specificity; D061221:Trigeminal Nerve Injuries