Diagnosis of Neuropathic Pain in Temporomandibular Joint Surgery

The diagnostic approach to the patient with postoperative neuropathic pain should start with a focused history and physical examination. Care should be taken to determine the patients’ primary cause of concern (hypoesthesia, anesthesia, pain) as well as the time course and inciting injury. If the patient has pain, it should be discerned whether the pain is spontaneous or provoked and any inciting or mitigating factors. To consider a history of pain as possibly neuropathic, the distribution should be neuroanatomically plausible, as should the inciting history [41].

Physical examination should focus on evidence of nerve injury, atrophy, or potential self-induced trauma. Palpation at the surgical site can give evidence of the etiology of the neuropathy, as well as the pathophysiology if dysesthesia is present. It is important to evaluate and consider other possible causes of chronic postsurgical pain, as persistent pain due to uncorrected pathology can be a significant confounding factor in determining the diagnosis. A minority of patients presenting with persistent pain postsurgically will have a primarily neuropathic etiology [42].

Neurosensory testing should be carried out as well. Multiple schema for neurosensory testing exist and suffer from the difficulty of standardization. Many advanced methodologies are now under use as well [43]. The authors utilize the three-level dropout clinical neurosensory test developed by Zuniga and Essick [44]. The presence of the defining characteristic of neuropathy should be present in the relevant neuroanatomic distribution [41]. Confirmatory testing should be performed if possible [41], with magnetic resonance neurography offering the best opportunity to locate the precise site of injury [45]. (Fig. 7.1, Tables 7.1 and 7.2)

Fig. 7.1 Sensory testing (unpleasant altered sensation) (Adapted from: Zuniga and Essick [44])

Table 7.1 Sensory testing for the patient with unpleasant altered sensation

Adapted from: Zuniga and Essick [44]

Table 7.2 Diagnostic criteria for posttraumatic pain dysesthesias neuropathic pain (Jensen et al. [1])

Adapted from: Zuniga and Essick [43]

^aT typical, V variable, R rare (information obtained during Step 1) ^bSee Fig. 4 for explanation of symbols

^c+, pain relieved by block; —, pain not relieved by block; blank, block not usually performed ^dProximal to site of injury