Several reports have described spinal or epidural anaesthesia resulting from attempted blockade of brachial plexus by interscalene route. Total spinal anaesthesia is very rare and may be due to anatomical variations, technical performance or both. An understanding of the factors associated with these complications may help to decrease their incidence.
CASE REPORT
A 35-year-old patient of American society of anaesthesiologists ASA grade 1 with fracture dislocation of the right head of radius and fracture lateral 3rd of the clavicle scheduled for surgery under brachial plexus block with sedation.After local anaesthesia with 2% lignocaine, a needle was advanced between belly of anterior and middle scalene at the level of cricoid cartilage or C6 as described by Winnie. After eliciting nerve paraesthesia, a mixture of 30 ml (0.5% bupivacaine - 20 ml + tramadol - 1 ml + 9 ml normal saline (NS) was injected slowly with negative aspiration after each 3-5 ml. Even after a proper caution patient moved his neck during the last 5 ml injection. Immediately after injection, the patient became unconscious and apnoeic, with loss of muscle tone in all extremities. Blood pressure decreased from 120/80 to 90/60 mmHg and pulse rate from 100 to 80 beats/min. No seizure activity was noted. He had a Glasgow Coma Score of 3 and had fixed dilated and unresponsive pupils. Intravenous fluid was administered, the patient was ventilated with oxygen 100% with a bag mask and his trachea was then intubated without the need for a neuromuscular blocking drug. Mechanical ventilation was instituted immediately with 100% oxygen. As the patient's vital parameters noninvasive blood pressure (NIBP - 106/70, heart rate (HR) - 78 beats/min) were stable, surgery was begun. It was suspected that total spinal anaesthesia had occurred. Pupils were initially noted to be widely dilated but gradually returned to normal size over the course of 1½ h. Patient's HR and blood pressure remained stable during 1st h post-injection, then the HR gradually decreased to 50 beats/min. 0.5 mg of atropine was given for bradycardia, HR gradually increased to 80 beats/min.After 1 h 15 min, spontaneous effort was seen gradually and patient was able to follow command and adequate tidal volume by 1 h 48 min. Patient was extubated with an adequate gag reflex. Patient was able to move all the extremities on the command except the operated right arm. There was no response by the patient to the surgical manipulation of the right arm. The right (operating) arm had proximal motor strength of 0/5. At 3 h post-injection, right arm strength and sensation had returned to normal. After completion of surgery, patient was shifted to an intensive care unit with oxygen via face mask. Close questioning on day one of the post-operative, revealed no recall of intra-operative events.
DISCUSSION
After interscalene blocks, various complications have been reported, including total spinal anaesthesia and Horner's syndrome.[12]In our case, the possibility of intrathecal injection of anaesthetic agent should be considered. Local anaesthetics can enter the spinal space through at least three different routes. First, the drug may be injected directly intrathecally. Second, a dural cuff sometimes may accompany a nerve root distal to the intervertebral foramen, which may be accidentally punctured, making direct intrathecal injection possible. All authors who reported total spinal anaesthesia claimed to have had negative aspiration tests, which therefore, did not guarantee absolute safety. Finally, local anaesthetics injected intraneurally could spread in a central direction to the spinal space. After near completion of block last few millilitre of anaesthetic was injected either to epidural or subarachnoid space at C6 probably by advancement of needle into the intervertebral foramina. Rapidity with which symptoms developed (unconsciousness, apnoea) argues for some degree of subarachnoid injection, although short needle used was intended to minimize the risk of this complication. The observation of initially dilated non-reactive pupil consistent with the loss of efferent parasympathetic activity from Edinger westphal nucleus and the observed bradycardia can be most easily explained by cervicothoracic spinal anaesthesia with the blockade of cardiac accelerator fibres (T1-T4).[3] This early sign persisted for 45 min, at which time HR decreased to 50 beats/min. This evidence of the high, but not intracranial blockade persisted for approximately 1½ h. At the conclusion of the case, patient appeared to have recovered completely.In our case, there is no recall of events which was consistent with previously published reports by Ross and Scarborough.[4] There was no seizure activity or myocardial depression that might have resulted from intravenous injection of lidocaine or bupivacaine.[5] Durrani and Winnie[6] have described a lock in syndrome resulting from probable intra-arterial injection accompanying a successful brachial plexus block but there was no seizure activity and this rules out intravascular injection of local anaesthetics. Unlike intravenous or intra-arterial injection, cerebrospinal fluid administration of local anaesthetics such as procaine caused nystagmus, defecation, vomiting, respiratory depression, loss of consciousness after 15-30 min but was not associated with seizure activity in a dog.[7]Despite high sympathectomy and some degree of the parasympathetic blockade at the brain stem level patient's HR and blood pressure remained at an acceptable level throughout and the patient did not require vasopressors or chronotropic drugs.[89] Direct application of local anaesthetics at the medullary region of the central nervous system results in hypotension, bradycardia, ventricular arrhythmias.[10]
CONCLUSION
In summary, we once again emphasise the importance of careful technique, monitoring, immediate access to resuscitation equipment while performing block.