To the Editor: The brachial plexus block is a suitable technique for surgical procedures of the upper extremities, although serious side effects have been reported. Direct injection into the spinal cord after interscalene block can cause permanent loss of cervical spinal cord function (1). Reversible loss of function from intrathecal injection and subarachnoidal spreading of the local anesthesia has been reported after the posterior approach (2). We report a case of permanent loss of cervical spinal cord function after the posterior approach. A healthy, 39-yr-old man, height 190 cm, weighing 100 kg, presented with left shoulder arthroscopic acromioplasty. The position was marked in sitting position. A flexible 10-cm 25-gauge stimulation needle (Stimuplex, B Braun, Melsungen, Germany) was introduced 3 cm left of the midline at the intervertebral space C6-7 in a supine position (3). The needle was advanced perpendicular to the skin in a sagittal plane, which was complicated by contact to a bony structure (lamina C6 or transverse process of C7), after which the needle was easily advanced further. Left upper extremity muscle twitches were obtained at 0.3 mA. After a negative attempt to draw blood or cerebrospinal fluid from the needle, 40 mL bupivacaine 0.375% with adrenaline 1:200,000 was injected. Immediately after injection, the patient reported an acute pain in his left arm. Next, total flaccid paralysis of all extremities, loss of consciousness, decrease of systolic blood pressure (<60 mm Hg), and apnea occurred. His trachea was intubated and his lungs were ventilated. Acromioplasty was initiated under general anesthesia and was performed without complications. Four hours after the operation, the patient awoke and was able to breathe spontaneously. Muscle strength recovered gradually in only his legs and right arm, whereas the paresis of his left forearm and hand persisted. Moreover, a left-sided Horner syndrome was noted. One week later, a cervical T2 weighted magnetic resonance imaging scan revealed increased signal intensity of the left paramedial spinal cord, from C4 to T1 (Fig. 2), which had decreased on a second T2 weighted magnetic resonance imaging scan 6 mo later (Fig. 3). Then, the Horner syndrome and wasting and weakness of both the left forearm, hand (MRC 2/5), and upper arm (MRC 4/5) persisted (Fig. 1). Moreover, pain and temperature sensation was diminished in the left dermatomes C7, C8 and Th1.Figure 2.: Cervicothoracic MRI, axial and sagittal T2-weighted images. One week after clinical onset: increased signal intensity of the spinal cord, left paramedially, extending from C4 to T1.Figure 3.: Cervicothoracic MRI, axial and sagittal T2 weighted images. 6 mo after clinical onset: significant decrease of the hyperintense lesion.Figure 1.: A and B, 6 mo after clinical onset: Horner syndrome of the left eye. Wasting of the left forearm and intrinsic hand muscles.In our patient, loss of consciousness most likely resulted from intrathecal injection with spinal subarachnoid spread of the local anesthetic. The paresis of the left upper extremity that persisted indicates that intramedullary injection had also occurred. Intravascular injection of the radicular artery is another possible mechanism (4), but this seems less likely. Direct injection of fluid into the spinal cord causes pressure and separation of glia cells or neurons (1). Bupivacaine might have a direct toxic effect on the ventral horn cells of C4-8 and spread into the ciliospinal center in the lateral horn of C8-T1 (5). Several factors support this hypothesis. Localizing in sitting position while advancing the needle in supine position might have contributed to a deviant direction. Next, the needle might have bent medially after bony contact and reached the myelum. Deviation of the tip of a flexible needle is a well-known risk and negative aspiration tests do not guarantee absolute safety (2). In addition, a rather large volume of local anesthetic was injected, which increases the risk of neurological damage (1). In short, direct intrathecal and intramedullary injection probably caused loss of cervical spinal cord function in this patient, which further questions the safety of the posterior approach (2). Nicol C. Voermans, MD* Ben J. Crul, MD, PhD† BertJan de Bondt, MD‡ Machiel J. Zwarts, MD, PhD§ Baziel G. M. van Engelen, MD, PhD* *Neuromuscular Center Nijmegen †Pain Expertise Center Nijmegen, Department of Anaesthesiology §Department of Clinical Neurophysiology Radboud University Nijmegen Medical Center Nijmegen, the Netherlands [email protected] ‡Department of Radiology University Medical Center Maastricht Maastricht, the Netherlands
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Jul 1, 2012
Todd A Hubbard + 2
Open Access