We read with interest the report of Blumenthal et al.1 of a case of prolonged neurologic deficits after regional anesthesia in a patient with an undiagnosed (subclinical) neuropathy. We congratulate the authors on the exemplary treatment of the patient with a neurologic complication—early evaluation, appropriate investigations, and adequate support and follow-up till resolution.

However, we are not clear how this case report should change our future practice. The author's opening statement that “Nerve injury is a well-recognized complication [italics our own] of peripheral nerve blocks” is misleading in that it implies that nerve injury related to regional anesthesia is a common occurrence. Large series have already shown that neurologic deficits after peripheral nerve block are mostly transient and, overall, very uncommon.2 Even neurologic complications specific to continuous catheter techniques are reported as infrequent.3 The etiology of neurologic complications is polyfactorial, and there are multiple possible causes of neurologic deficit after surgery, most of which are more common than those related to the regional anesthetic technique.4,5 Even in this case, with the evidence from the investigations conducted, it is not absolutely certain that the tourniquet was not at least partly responsible for the nerve injury.

This case does, however, highlight the complications associated with subclinical neuropathy. These are probably more common than appreciated, given the high incidence of diabetes (and other causes of neuropathy) in our clinical workload. The preoperative diagnoses of a subclinical neuropathy may not be possible unless specific preoperative investigations are directed toward this etiology. Further, there may be an overall increased susceptibility to the other etiologies of nerve injury.6,8 Whether the finding of this risk factor will lead to fewer patients being offered regional anesthesia (and/or tourniquets) is speculative and open to further discussion. Nonetheless, the results of this case further reinforce the fact that in the unfortunate event of a postoperative neurologic deficit, the findings of preexisting subclinical neuropathy could become important. Advocacy of regional anesthesia and careful discussion of its benefits (balanced by its risks) should begin preoperatively and continue even in the event of an adverse outcome or complication. We believe that the benefits of peripheral nerve blocks are significant and the risks, although present, are very low and that regional anesthesia should be offered to all suitable patients.

1
Blumenthal
S
,
Borgeat
A
,
Maurer
K
,
Beck-Schimmer
B
,
Kliesch
U
,
Marquardt
M
,
Urech
J
:
Preexisting subclinical neuropathy as a risk factor for nerve injury after continuous ropivacaine administration through a femoral nerve catheter.
Anesthesiology
2006
;
105
:
1053
6
2
Capdevila
X
,
Pirat
P
,
Bringuier
S
,
Gaertner
E
,
Singelyn
F
,
Bernard
N
,
Choquet
O
,
Bouaziz
H
,
Bonnet
F
:
Continuous peripheral nerve blocks in hospital wards after orthopedic surgery: A multicenter prospective analysis of the quality of postoperative analgesia and complications in 1,416 patients.
Anesthesiology
2005
;
103
:
1035
4
3
Neuburger
M
,
Breitbarth
J
,
Reisig
F
,
Lang
D
,
Buttner
J
:
Complications and adverse events in continuous peripheral regional anesthesia: Results of investigations on 3,491 catheters [in German].
Anaesthesist
2006
;
55
:
33
40
4
Eipe
N
,
Padhi
NR
:
Tourniquet palsy or residual block?
Anesth Analg
2005
;
100
:
903
4
5
Brull
R
,
McCartney
CJ
,
Chan
VW
,
Abbas
S
,
Nova
H
,
von Schroeder
H
,
Katz
J
:
Effect of transarterial axillary block versus general anesthesia on paresthesiae 1 year after hand surgery.
Anesthesiology
2005
;
103
:
1104
5
6
Landi
A
,
Saracino
A
,
Pinelli
M
,
Caserta
G
,
Facchini
MC
:
Tourniquet paralysis in microsurgery.
Ann Acad Med Singapore
1995
;
24
:
89
93
7
Horlocker
TT
,
O'Driscoll
SW
,
Dinapoli
RP
:
Recurring brachial plexus neuropathy in a diabetic patient after shoulder surgery and continuous interscalene block.
Anesth Analg
2000
;
91
:
688
90
8
Hebl
JR
,
Horlocker
TT
,
Sorenson
EJ
,
Schroeder
DR
:
Regional anesthesia does not increase the risk of postoperative neuropathy in patients undergoing ulnar nerve transposition.
Anesth Analg
2001
;
93
:
1606
11