INTRODUCTION:

Administration of local anaesthesia is one of the commonest procedures undertaken in dentistry. It is an effective and safe means of pain control that allows routine procedures to be undertaken [1]. The history of local anaesthesia started when cocaine was isolated by Niemann. In 1884, Koller was the first person who used cocaine for topical anaesthesia.

In 1884, the surgeon Halsted first performed regional anaesthesia in the oral cavity when he removed wisdom tooth without pain. When he removed a wisdom tooth without pain. In 1905, Einhorn reported the synthesis of procaine, which was the first ester-type local anaesthetic agent. Procaine was the most commonly used local anaesthetics for more than four decades. In 1943, Lofgren synthesized lidocaine, which was the first modern local anaesthetic agent. Lidocaine was marketed in 1948 and is currently the most commonly used local anaesthetic in dentistry worldwide [2]. Complications related to local anaesthesia can be divided into two categories: preoperative and postoperative complications [3]. There are numerous routes to achieving local anaesthesia in dentistry. In the maxilla, infiltrations (e.g. buccal and palatal) are commonly employed, as well as nerve blockade of the posterior superior alveolar and the infra-orbital nerves. In the mandible there are lingual and buccal nerve infiltrations as well as the inferior alveolar, lingual and mental nerve blocks. Complications arising from inferior alveolar nerve block are facial nerve palsy, immediate palsy, delayed palsy, transient amaurosis, total body hemiparesis, Post-injection Paraesthesia, Horner’s Syndrome, Transient Paralysis of Combinations of Cranial Nerves, sudden unilateral deafness. Complications arising from posterior superior alveolar nerve block are Peripheral Facial Nerve Palsy, Abducens Nerve Palsy, Temporary Blindness [4]. Both preoperative and postoperative complications can be avoided with correct technique and dosage. However if complications occur, dental students should know how to manage them [3]. Hence the main aim of this study is to create awareness and to evaluate knowledge of neurological complications and its management while administering local anaesthesia among dental students.

MATERIALS AND METHODS:

This study was conducted among 100 dental students in Saveetha dental college. The questionnaire consisting of 12 questions were prepared regarding their knowledge on complications arising from inferior alveolar nerve block, posterior superior alveolar nerve block, duration of facial nerve palsy to clinically appear, duration of effects from total body hemiparesis, onset time of delayed palsy, symptoms of facial nerve palsy, symptoms of abducent facial nerve palsy, symptoms of horner’s syndrome, pharmacological management of bells palsy, surgical management of facial nerve palsy, methods to avoid neurological complications. Each correct answer was given scores and their knowledge was assessed. The score between 0-3 were considered as the inadequate knowledge, the score between 4-7 were considered as the moderate knowledge, the score between 8-11 were considered as the adequate knowledge.

RESULTS:

57% of dental students were interns, 43% were post graduate students. From chart 1, it is found that 33.3% of dental students felt that only facial nerve palsy as a complication of inferior alveolar nerve block.3.3% of dental students felt that only immediate palsy as a complication of inferior alveolar nerve block. 5% felt that only chronic orofacial pain arises as complications from inferior alveolar nerve block.7% only aware that all (facial nerve palsy, immediate palsy, chronic orofacial pain) are the complications of inferior alveolar nerve block. From chart 2, it is found that 13.3% of dental students felt that only peripheral nerve palsy is the complication arising from posterior superior alveolar nerve block. 6.6% of dental students felt that only temporary blindness arises as a complication of posterior superior alveolar nerve block.46% of dental students aware that all (peripheral nerve palsy, abducent nerve palsy, temporary blindness) arises as a complication of posterior alveolar nerve block. From chart 3, it is found that 44% of dental students aware on onset time of immediate facial nerve palsy. From chart 4, it is found that 70% of dental students aware on the onset time of delayed palsy. From chart 5, it is found that 26% of dental students aware on the symptoms of abducent nerve palsy. From chart 6, it is found that 54% of students aware on symptoms of facial nerve palsy. From chart 7, it is found that 30% of dental students aware on the duration of effects from total body hemiparesis. From chart 8, it is found that 43% of dental students aware on symptoms of Horner’s syndrome .From chart 9, it is found that 26% of dental students aware on pharmacological management of bell’s palsy. From chart 10, it is found that Only 10%ofdental students felt that knowledge on anatomy will prevent neurological complications,6.6% of dental students felt that right technique will prevent neurological complications. 73.3% aware that both knowledge on anatomy, right technique will prevent neurological complications. From chart 11,it is found that 27% of dental students felt that nerve compression is the only surgical management of facial nerve palsy, 10% of dental students felt that facial nerve grafting of facial nerve is the only surgical management of facial nerve palsy.53.3% aware that all (nerve compression, facial nerve grafting, Tarsorrhaphy are that surgical management of facial nerve palsy. From chart 12, it is found that 30% of dental students have inadequate knowledge on neurological complications and its management while administering local anaesthesia, 60% of dental students have moderate knowledge on neurological complications and its management while administering local anaesthesia,10% of dental students have adequate knowledge on neurological complications and its management while administering local anaesthesia.

Chart 1:Dental studentsawareness on complications arising from inferior alveolar nerve block

Chart 3: Dental students awareness on onset of immediate facial nerve palsy

Chart 4:Dental students awareness on onset time of delayed palsy

Chart 5:Dental students awareness on symptoms of abducent nerve palsy

Chart 6:Dental students awareness on symptoms of facial nerve palsy

Chart 7: Dental students awareness on duration of effects from total body hemiparesis

Chart 8: Dental students awareness on symptoms of horner’s syndrome

Chart 9: Dental students awareness on pharmacological management of bell`s palsyChart

10: Dental students awareness on methods to avoid neurological complications

Chart 11: Dental students awareness on surgical management of facial nerve palsy

Chart 12:Percentage of dental students in each category

DISCUSSION:

57% of dental students were interns 43% were post graduate students. 33.3% of dental students felt that only facial nerve palsy as a complication of inferior alveolar nerve block.3.3% of dental students felt that only immediate palsy as a complication of inferior alveolar nerve block.5% felt that only chronic orofacial pain arises as a complication from inferior alveolar nerve block.7% only aware that all (facial nerve palsy, immediate palsy, chronic orofacial pain) are the complications of inferior alveolar nerve block. Aburas in his study reported that 82% of dental students aware on facial nerve palsy, 8% of dental students aware on idiopathic facial granuloma, 10% of dental students aware on chronic orofacial pain [5].

The mechanism of facial weakness after dental procedure can be explained by direct anaesthesia to the facial nerve can force a rapid onset that occurs while the anaesthetic agent is being injected, reflex vasospasms of the external carotid artery can lead the ischemia of facial nerve, and dental infections may secondarily affect the facial nerve [6,7]. Facial nerve palsy following inferior alveolar nerve block may appear immediately or be delayed [4]. The immediate type occurs due to the direct accidental injection of anaesthesia of one or more branches of facial nerve. This is possible when an intra-glandular injection of the anaesthesia occurs. If the injection is administered too far posterior, the anaesthetic solution could be injected into the parotid substance. Most often, the gland envelopes the facial nerve, thus leading to the direct anaesthesia of the latter. However, there are cases in which the gland fails to envelop the nerve and its divisions or the branches of the facial nerve appear to be aberrant in the retro-mandibular space [1,2,3]. such deviations from normal anatomy increase the chances of direct exposure to local anaesthetic solution even if the anaesthesia is administered properly [8,9,10,11,12].

A number of studies have reported trigeminal nerve injury in relation to local anaesthetic block injections. The nerve injury may be physical from the needle or chemical from the local anaesthetic solution [13].

13.3% of dental students felt that only peripheral nerve palsy is the complication arising from posterior superior alveolar nerve block.6.6% of dental students felt that only temporary blindness arises as a complication of posterior superior alveolar nerve block.46% of dental students aware that all (peripheral nerve palsy, abducent nerve palsy, temporary blindness) arises as a complication of posterior alveolar nerve block. The central retinal artery is a small branch of the ophthalmic artery; any anaesthetic solution flowing through the middle meningeal artery may enter the ophthalmic artery and further the retinal artery causing blindness and loss of pupillary light reflex [14]. Peripheral facial nerve palsies have been reported following the administration of Posterior superior alveolar nerve (PSA) block. Intra-arterial injections and intravenous absorption are two possible means of vascular transport of the anaesthetic solution into the orbital region [15]. Inadvertent venous injection has the chance of depositing the solution too close to pterygoid plexus present within the infra-temporal fossa .Anaesthetic agent in close vicinity to pterygoid plexus causes diffusion of solution into the thinned walled vessel Via emissary vein enter the cavernous sinus affecting abducens nerve causing post injection abducens palsy [16].

44% of dental students aware on onset time of immediate facial nerve palsy.70% of dental students aware on the onset time of delayed palsy. Aburas in his study reported that 40% of dental professional s aware on the onset time of delayed palsy [5]. In the immediate type, the paralysis occurs within minutes of injection. It has a recovery period of 3 hours or less. However, in the delayed type the symptoms appear within several hours to several days, while recovery may expand from 24 hours to several months [17].

26% of dental students aware on the symptoms of abducent nerve palsy.54% of students aware on symptoms of facial nerve palsy. The abducens (sixth) cranial nerve controls the lateral rectus muscle, which abducts the eye. The affected eye turns in toward the nose and is unable to abduct properly. The patient may complain of double vision and may exhibit limitation of abduction of the ipsilateral eye as well as paraesthesia of the lateral side of the upper and lower eyelids. The symptoms of facial nerve palsy include generalized weakness of the ipsilateral side of the face, inability to close the eyelids; obliteration of the nasolabial fold; drooping of the corner of the mouth and deviation of the mouth to the unaffected side. They may also complain of pain in the retro auricular area and a decreased taste sensation [4].

30% of dental students aware on the duration of effects from total body hemiparesis. Aburas repoted in his study 29% of dental students aware on the duration of effects from total body hemiparesis [5]. Following inferior alveolar nerve block, total body hemiparesis was reported. The mechanism behind this reported case was found to be inadvertent intravascular injection of local anaesthetic with subsequent retrograde internal movement in branches of the internal carotid artery. This comprised ptosis, occipital, neck stiffness, anaesthesia of the right side of the face with dysphasia, and led to complete aphasia and a right hemiparesis. The effects lasted for approximately 45 min and were attributed to excess pressure created during the administration of the injection leading to a retrograde flow into the internal carotid artery [18].

43% of dental students aware on symptoms of Horner’s syndrome. A rare complication following an inferior dental nerve block, reported by Campbell et al.,17 is the development of Horner’s syndrome. This syndrome occurs due to the penetration of local anaesthetic solution through the lateral laryngeal pharyngeal nerve and prevertebral spaces leading to the blockade in the stellate ganglion. The features of the syndrome include flushing of the face on the same side, ptosis of the eyelid, vasodilatation of the conjunctiva, pupillary constriction, (occasionally) a rash over the neck, face, shoulder and arm of the ipsilateral side, hoarse voice, difficulty in breathing due to the involvement of recurrent laryngeal nerve [4].

26% of dental students aware on pharmacological management of bell`s palsy. Corticosteroids have anti-inflammatory action that should minimise nerve damage and thereby improve the outcome. The prednisolone dose used was 60 mg per day for 5 days then reduced by 10 mg per day (for a total treatment time of 10 days) and 50 mg per day (in two divided doses) for 10 days. The reported adverse rates were low. Treatment with prednisolone is likely to be cost-effective [19].

Only 10% of dental students felt that knowledge on anatomy will prevent neurological complications,6.6% of dental students felt that right technique will prevent neurological complications.73.3% aware that both knowledge on anatomy, right technique will prevent neurological complications. Standard precautions such as aspiration, slow injection could minimize possible side effects. Knowledge on anatomy will also prevent neurological complications [3].

27% of dental students felt that nerve compression is the only surgical management of facial nerve palsy, 10% of dental students felt that facial nerve grafting of facial nerve is the only surgical management of facial nerve palsy. 53.3% aware that all (nerve compression, facial nerve grafting, Tarsorrhaphy are that surgical management of facial nerve palsy. Because of the wide variation in the potential for regeneration and lack of reliable prognostic indicators for spontaneous recovery, the evaluation and treatment of facial paralysis is especially intricate [20].The patient's age, medical history, residual hearing, segment of nerve injured, and the patient's expectations and risk tolerance must be noted for surgical intervention of facial nerve paralysis [21].

The transmastoid approach allows decompression of facial nerve when the trauma is clearly localized to the tympanic or mastoid segments of the facial nerve. The nerve should be decompressed for 180 degrees of its circumference. The middle fossa approach allows decompression of the facial nerve when the injury extends to the labyrinthine segment. The translabyrinthine approach can be utilized for decompression of the entire intra-temporal course of the facial nerve in cases where cochleovestibular function is absent or has been destroyed by the trauma [22].

Temporary suture tarsorrhaphy involves using absorbable or non-absorbable suture to close the eyelids. Bolsters can be used to prevent the suture from pulling through the eyelid and a releasable technique can allow intermittent opening of the eyelids for corneal examination [23,24,25].

30% of dental students have inadequate knowledge on neurological complications and its management while administering local anaesthesia, 60% of dental students have moderate knowledge on neurological complications and its management while administering local anaesthesia, 10% of dental students have adequate knowledge on neurological complications and its management while administering local anaesthesia. Aburas in his study reported that specialists had a better knowledge regarding some of the local anaesthesia complications whereas undergraduate and dental interns had less amount of knowledge [5].

CONCLUSION:

Most of the dental students have moderate knowledge on neurological complications and its management while administering local anaesthesia. Although neurologic complications occur rarely, dental students should keep in mind that certain dental procedures, such as inferior alveolar block anaesthesia, posterior superior alveolar nerve block can cause some neurological complications. Attention should be paid during the administration of the anaesthetic solution. Following standard precautions and knowledge on neurological complications management among dental students is necessary to minimize its side effects. Hence awareness should be created among dental students on neurological complications and its management while administering local anaesthesia.

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Received on 12.04.2018 Modified on 31.05.2018

Research J. Pharm. and Tech 2019; 12(2):483-488.

DOI: 10.5958/0974-360X.2019.00085.4