Severe adverse reactions to dental local anaesthetics: prolonged mandibular and lingual nerve anaesthesia.

BACKGROUND: Prolonged anaesthesia may occur following dental local anaesthetic blocks. This paper reviews the possible mechanisms of injury. Direct injury to the nerve by the needle, although commonly thought to be the mechanism, is unlikely. It is much more likely that the injury is from neurotoxicity and/or interference with the vascularization of the nerve. METHODS: Estimation of the frequency of injury was complicated by the fact that although local anaesthetics are prescription-only (S4) drugs, they are supplied without prescription by dental supply houses. Unlike all other S4 drugs, there is no statutory requirement to record supply. The pharmaceutical and supply houses relied on that and 'commercial confidentiality' to not supply information. RESULTS: An informed estimate of 1 in 27 415 was made but this figure has wide confidence limits. Management of cases of prolonged anaesthesia following local anaesthetic injection is discussed. CONCLUSIONS: Patients who suffer this uncommon complication suffer considerable distress and feel injured, so care must be exhibited in their management. Specialist referral is recommended.

An unusual relationship between the inferior alveolar nerve, lingual nerve and maxillary artery / Una inusual relación entre los nervios alveolar inferior y lingual y la arteria maxilar

The knowledge of the neurovascular relationships of the infratemporal region is relevant in odontostomatology practice. In this article we present a case of atypical communication between the inferior alveolar nerve and lingual nerve associated with a change in relations with the maxillary artery, and discusses some clinical implications that these relations have on the development of the suplementary innervation and the anesthesia.

El conocimiento de las relaciones entre los elementos neurovasculares de la región infratemporal es relevante en la práctica odontoestomatológica. En el presente artículo presentamos el caso de una comunicación atípica entre el nervio alveolar inferior y el nervio lingual asociados a una variación en las relaciones con la arteria maxilar, y sediscut en algunas implicancias clínicas que estas relaciones tienen en el desarrollo de inervación suplementaria y en la práctica anestésica.

Anatomical variations and clinical implications of the artery to the lingual nerve.

The pterygomandibular space is a critical anatomic area for the delivery of local anesthesia in the practice of dentistry. The neurovascular contents of this area are subject to trauma and its resultant local and systemic complications. This study of 202 cadaveric specimens reaffirms the literature as to the percent distributions of the superficial and deep routes of the maxillary artery and details for the first time the anatomic variations of the artery to the lingual nerve. This artery courses through the pterygomandibular space placing it at risk for injection trauma along with the other neurovascular contents. It has been uncommonly identified and referred to in the literature, yet it may be the first artery encountered when entering the space with a needle or during surgical intervention in the area.

Innervation of human trigeminal nerve blood vessels.

Film preparations and histological sections of human trigeminal nerve impregnated with silver nitrate and treated according to Falck-Hillarp revealed a rich innervation within the intraneural blood vessels. Highly diverse and complex neural interconnections were noted in the arterioles and venules of the trigeminal ganglion capsule as well as in the epineurium and external layers of the perineurium of the trigeminal nerve branches. Neural plexuses were detected on the vessel walls within these layers. Sensory innervation of the neural blood vessels was mainly relegated to polyvalent tissue-vascular receptors with adrenergic neural plexuses encountered on the walls of the intraneural vessels.

The blood supply of the hypoglossal nerve and its relevance to carotid endarterectomy.

Since the hypoglossal nerve is liable to injury during carotid endarterectomy and similar procedures, its blood supply was examined in microinjection studies of human cadavers. The nerve is supplied by arteries that arise from the ascending pharyngeal artery as it exits from the hypoglossal canal, the occipital artery as the nerve passes under its branch to the sternomastoid muscle, direct branches from the external carotid artery, and branches from the ascending pharyngeal artery just near the bifurcation of the common carotid artery. Within and close to the tongue, the nerve is supplied by branches from the lingual artery. Damage to the vessels supplying the nerve may account for some cases of hypoglossal palsy after carotid endarterectomy. Possible mechanisms are ischaemia, thermal or electrical injury from diathermy current conducted to the nerve, or intraneural haematoma from rupturing one or more of these fine vessels.