Truncular anaesthesia of the inferior alveolar nerve, especially in the classic technique of the inferior alveolar block, is a routine procedure in dental practice, although it is subject to difficult elements concerning the operation technique, the failure rate and the possible need for a second administration, and the onset of complications. Ocular complications, although rare and usually benign and transient (from hours to days in this case), like the others, may be particularly worrying for the patient and also for the clinician. It is therefore important for the clinician to be able to recognise a situation of this kind, in order to prepare the correct approach.
Among the complications of the eyeball, in the literature there are reports of diplopia (the most common among these, 39.8% of cases), ptosis (16.7%), mydriasis (14.8%), miosis, enophthalmos, ophthalmoplegia, retrobulbar pain and blurred vision and amaurosis (13%), this last one being the main topic of discussion, with reference to the recent publication by Pandey and colleagues. All these conditions, in the iatrogenic form, are manifested on an extrinsic basis, in other words for direct or indirect contact (intravascular administration) between the anaesthetic molecule and the neuromuscular apparatus of the opulomotor or the optic nerve (II pair of cranial nerves). They more commonly follow the block of the inferior alveolar nerve (45.8% of cases) but also the posterior superior one (40.3%).
Amaurosis represents partial or complete loss of vision in an eye. Pandey attaches the case report of a woman who, as soon as she underwent the lower alveolar block for an endodontic treatment, reported blurred vision in the ipsilateral eye, becoming complete blindness after another 25-30 seconds. The clinician reported having administered 1.8 ml (1 tube) of 2% lidocaine-based solution with vasoconstrictor (adrenaline 1:100000) via a 30 mm 28 Gauge needle – note that the aspiration test was performed, with a negative result.
The clinician discontinued the treatment, positioning the patient supine and monitoring her neurological status (with particular attention to oculomotor function), which otherwise proved negative. The symptom of blindness resolved itself within 15 minutes, and after a further quarter of an hour the patient no longer reported any visual limitation. The patient was monitored for 1 hour and called back in after 2 days.
It should be noted that the authors conclude by linking the episode to the effects of intravascular administration in the maxillary artery, with involvement of the middle meningeal branch and, therefore, to a case of a false negative in the aspiration test. The preventive measures are not simple with regard to recognising any parts of the anatomy at risk, so the authors propose performing the aspiration test twice, keeping the patient calm in order to avoid micromovements after the test itself, and paying attention to the liquid release pressure.