Source: Borgeat et al. Anesth 2001; 95(4): 875-80

Reviewer:  R. Prasad, MD

Summary:

• Short- and severe long-term (>9 mo) complication rate 0.4%
• Unrelated to presence of catheter
• If persistent paresthesia/dysesthesia unrelated to surgery, should rule out sulcus ulnaris syndrome (SUS), carpal tunnel syndrome (CTS), and complex regional pain syndrome (CRPS), all of which have specific early treatments

• How long were infusions continued?
• Were symptoms correlated with current levels required to stimulate?
• There was a trend (NS) for fewer complications with catheter group
• Relatively large doses used - at least, probably more than required - for initial boluses
• Would have liked a control group of GA only

• 521 consecutive adult pts for elective shoulder or upper arm surgery
• Standardized ISB with nerve stimulator to <0.5 mA, B-bevel needle, 20G catheters 3-4cm, ropiv 0.6% 40ml for <60kg, 50ml >60kg. Infusions, if used, were started 6h after block.
• Frequent monitoring for 9months, with electroneurography if developed severe or worsening symptoms

• 234 catheter, 286 single injection. Mean current 0.36 (0.2-0.46), with radial n (triceps) stimulated in 98% (20% with concurrent biceps twitch) and axillary n (deltoid) in 2%
• Demographics similar
• Pts with catheter had longer surgery (152 vs 75min) and more concurrent GA (52% vs. 7.3%)
• Acute Complications (all mild)
• CNS toxicity, 1 (0.2%)
• Pneumothorax, 1 (0.2%)
• Blood aspiration, 3 (0.6%)
• Unsuccessful, 3 (0.6%)
• Transient paresthesias/dysesthesia, 21%
• Transient pain during cath placement, 6.4%
• Catheters left in median 3 d (range 2-5d)
• Complication rate (paresthesia, dysesthesia, or pain unrelated to surgery) by time (no signif diff in btwn those with or without catheters):

• Nonacute Complications
• Sulcus ulnaris syndrome, 8 (1.5%)
• CRPS, 5 (1%)
• CTS, 4 (0.8%)
• Plexus neuropathy, 1 (0.2%)
• Severe plexus damage, 1 (0.2%)

• The 1 pt with severe long-term comlicatoins had an uneventful ISB (no paresth, no pain on injection). First week course normal - did not complain of sx till 10d. Sx mild initially, worsened after 2mo. EMG showed damage at C6 root level. Repeat EMG 9mo later showed complete recovery, but still c/o some sensory deficits
• Cause of neurologic trauma after ISB unclear - needle trauma, intraneural injection, local anesthetic toxicity, unrelated plexus stretching or compression, inflammation
• Conclusions re ISB with their standardized protocol:
• High success rate
• High incidence of transient problems (14% at 10d)
• Very low long-term complications (0.2% at 9mo)
• No association with catheter presence

sulcus ulnaris syndrome - "entrapment neuropathy of the ulnar nerve at the medial epicondyle of the elbow"

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carpal tunnel syndrome - "entrapment neuropathy of median nerve in the carpal tunnel between the longitudinal tendons of forearm muscles that flex the hand and the transverse superficial carpal ligament"

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