Spinal accesory nerve blockade by local infiltration for central venous catheter insertion: An unusual occurrence.

Sir,

Neurological complications like damage to phrenic nerve, brachial plexus, recurrent laryngeal nerve, cervical roots, and cranial nerves have been attributed to central venous catheterization (CVC) via internal jugular vein (IJV).[1] These complications are mainly due to direct trauma by the needles or hematoma formation. We encountered a case where local anesthetic (LA) infiltration done for CVC insertion, produced an inadvertent transient blockade of spinal accessory nerve (SAN) with clinical features.

A 50-year-old male patient with enterocutaneous fistula required CVC insertion for total parenteral nutrition in the ward. He was a known case of coronary artery disease along with moderate arrhythmia (AR) and atrial fibrillation (AF), was on low dose aspirin (75 mg/day), and had a normal coagulogram (INR-1.5). Right IJV cannulation was planned through posterior approach to prevent carotid artery puncture. After procedural explanation, the patient was positioned and draped. Total 4 ml of 2% lignocaine was used to infiltrate the skin using a 26 G needle at the junction of middle and lower third of the sternocleidomastoid (SCM). CVC insertion proceeded uneventfully and was accomplished in a single attempt in approximately 10 min. No pain or paresthesia was complained by the patient during the procedure. Immediately after the procedure as the patient was changing position, he complained of weakness in the right shoulder. On asking the patient to raise the shoulder against resistance or abducting the right arm above the shoulder, he could barely do so. Weakness was also observed when the patient was asked to turn the head to left side against resistance. Apart from this no sensory or motor deficits were observed. Based on clinical suspicion, the patient was shifted to radiology department where an emergency ultrasonography (USG; within 10 min) of the neck revealed that the local anesthetic had seeped through the muscle planes and deposited around the site of exit of SAN behind the SCM [Figure 1]. The patient was reassured and observed closely. In the next 2 h a gradual improvement in the weakness was observed and by 3 h the power in the affected muscles normalized without any residual deficits.

Figure 1

Local anaesthetic deposition around the Spinal Accessory Nerve

The SAN is the main motor supply of SCM and trapezius which after piercing the SCM, traverses its posterior border just above the midpoint, emerging in the posterior triangle of neck superficially.[2] In our case, use of posterior approach, higher volume of LA, and Trendelenberg position causing LA to gravitate may have contributed to the blockade of SAN. Injury to SAN using the posterior approach has been mentioned previously in two reports,[34] but here direct trauma by needle had been implicated. Our suspicion of LA blockade was based on the absence of pain, paresthesia, time duration of onset of weakness, and the particular muscles involved which was confirmed by the USG demonstration of LA deposition around the nerve, transientness, and reversibility of the phenomenon. Clinicians should thus be aware of this potential complication during IJV cannulation. USG-guided cannulation and use of small volumes of dilute LA are the possible methods to circumvent this complication.