Kenneth D. Candido

Neurologic sequelae after interscalene brachial plexus block for shoulder/upper arm surgery: The association of patient, anesthetic, and surgical factors to the incidence and clinical course

We determined the incidence, distribution, and resolution of neurologic sequelae and the association with anesthetic, surgical, and patient factors after single-injection interscalene block (ISB) using levobupivacaine 0.625% with epinephrine 1:200,000 in subjects undergoing shoulder or upper arm surgery, or both, in 693 consecutive adult patients. After a standardized ISB, assessments were made at 24 and 48 h and at 2 and 4 wk for anesthesia, hypesthesia, paresthesias, pain/dysesthesias, and motor weakness. Symptomatic patients were monitored until resolution. Subjects reporting pain or discomfort >3 of 10 and those with motor or extending sensory symptoms received diagnostic assessment. Six-hundred-sixty subjects completed 4 wk of follow-up. Fifty-eight neurologic sequelae were reported by 56 subjects. Symptoms were sensory except for two cases of motor weakness (lesions identified distant from the ISB site). Thirty-one sequelae with likely ISB association were reported by 29 subjects, including 14 at the ISB site, 9 at the distal phalanx of thumb/index finger, 7 involving the posterior auricular nerve, and 1 clinical brachial plexopathy. Sequelae not likely associated with the ISB were reported by 27 subjects with symptoms reported in the median (n = 9) and ulnar (n = 4) nerves, surgical neuropraxias (n = 12), and motor weakness (n = 2). Symptoms resolved spontaneously (median 4 wk; range, 2–16 wk) except in the two patients with motor weaknesses and the patient with clinical brachial plexopathy, who received therapeutic interventions. Variables identified as independent predictors of neurologic sequelae likely related to ISB were paresthesia at needle insertion and ISB site pain or bruising at 24 h. In contrast, surgery preformed in the sitting position, as well as ISB site bruising, was identified as a predictor of neurologic sequelae not likely related to ISB. In conclusion, neurologic sequelae after single-injection ISB using epinephrine mainly involve transient minor sensory symptoms.

Post-dural puncture headache: pathophysiology, prevention and treatment

Post-dural puncture headache (PDPHA) has been a vexing problem for patients undergoing dural puncture for spinal anaesthesia, as a complication of epidural anaesthesia, and after diagnostic lumbar puncture since Bier reported the first case in 1898. This Chapter discusses the pathophysiology of low-pressure headache resulting from leakage of cerebrospinal fluid (CSF) from the subarachnoid to the epidural spaces. Clinical and laboratory research over the last 30 years has shown that use of small-gauge needles, particularly of the pencil-point design, is associated with a lower risk of PDPHA than traditional cutting point needle tips (Quincke-point needles). A careful history can rule out other causes of headache. A positional component of headache is the sine qua non of PDPHA. In high-risk patients (e.g. age < 50 years, post-partum, large-gauge-needle puncture), patients should be offered early (within 24-48 h of dural puncture) epidural blood patch. The optimum volume of blood has been shown to be 12-20 ml for adult patients. Complications of autologous epidural blood patch are rare.

Infragluteal-parabiceps sciatic nerve block: An evaluation of a novel approach using a single-injection technique

Clinical use of the sciatic nerve block (SNB) has been limited by technical difficulties in performing the block using standard approaches, substantial patient discomfort during the procedure, or the need for two injections to block the tibial and peroneal nerves. In this report, we describe a single-injection method for SNB using an infragluteal-parabiceps approach, where the nerve is located along the lateral border of the biceps femoris muscle. SNB was performed in the prone or lateral decubitus position. The needle was positioned (average depth, 56 ± 15 mm) to the point where plantar flexion (53%) or inversion (45%) of the ipsilateral foot was obtained at ≤0.4 mA. Levobupivacaine 0.625% with epinephrine (1:200:000) was administered at a dose of 0.4 mL/kg. The procedure was completed in 6 ± 3 min. Discomfort during block placement was treated with fentanyl 50–100 &mgr;g in 24% of patients. Complete sensory loss and motor paralysis occurred in 92% of subjects at a median time of 10 (range, 5–25) min after injection. Compared with plantar flexion, foot inversion was associated with a more frequent incidence (86% versus 100%), and shorter latency for both sensory loss and motor paralysis of the peroneal, tibial, and sural nerves. There were no immediate or delayed complications. We conclude that the infragluteal-parabiceps approach to SNB is reliable, efficient, safe, and well tolerated by patients.

Intrathecal neurolytic blocks for the relief of cancer pain

Intrathecal neurolytic blocks for the treatment of chronic pain were first described by Dogliotti in 1931. Since then, many authors have described the intrathecal injection of various neurolytic substances for the treatment of oncologic pain. In recent years, alcohol and phenol have been the substances most commonly used for this purpose. There are no controlled studies, so the literature consists of observations, reports and book chapters reflecting the opinions of experienced clinicians. This chapter describes the indications, contraindications, potential complications, and expected benefits of intrathecal injection of alcohol and phenol in the treatment of cancer pain. Four cases of cancer patients whose intractable pain was treated by the authors using intrathecal neurolysis are presented. Pertinent literature is reviewed. In this account, the emphasis is on proper selection of patients and techniques.

Nerve stimulator-assisted evoked motor response predicts the latency and success of a single-injection sciatic block.

Variable onset latency of single-injection sciatic nerve block (SNB) may result from drug deposition insufficiently close to all components of the nerve. We hypothesized that this variability is caused by the needle tip position relative to neural components, which is objectified by the type of evoked motor response (EMR) elicited before local anesthetic injection. One-hundred ASA I–II patients undergoing reconstructive ankle surgery received infraglutealparabiceps SNB using 0.4 mL/kg (maximum 35 mL) of levobupivacaine 0.625%. The endpoint for injection was the first elicited EMR: inversion (I), plantar flexion (PF), dorsiflexion (DF), or eversion (E) at 0.2–0.4 mA. The frequencies of the EMRs were: I 40%, PF 43%, E 14%, and DF 3%. SNB was considered complete if both tibial and common peroneal nerves were blocked and failed if either analgesia to pinprick was not observed at 30 min or anesthesia at 60 min. Patients with an EMR of I demonstrated shorter mean times (±95% confidence interval [CI]) to complete the block with 8.5 (95% CI, 6.2–10.8) min compared to 27.0 (95% CI, 20.6–33.4) min after PF (P < 0.001) and 30.4 (95% CI, 24.9–35.8) min after E (P < 0.001). No rescue blocks were required in group I compared with 24% (P = 0.001) and 71% (P < 0.001) of patients in groups PF and E, respectively. We conclude that EMR type during nerve stimulator-assisted single-injection SNB predicts latency and success of complete SNB because the observed EMR is related to the positioning of the needle tip relative to the tibial and common peroneal nerves.

A randomized comparison of a modified intertendinous and classic posterior approach to popliteal sciatic nerve block.

INTRODUCTION: In this prospective randomized study, we compared a single-injection modified intertendinous (n = 55) with the classic posterior (n = 54) popliteal sciatic nerve block for patients undergoing ankle/foot surgery. METHODS: Nerve stimulator-guided blocks were performed 7–8 cm (classic posterior) or 12–14 cm (modified intertendinous) above the popliteal crease. Levobupivacaine 0.625% with epinephrine 1:300,000 (Chirocaine®, Purdue Pharma, Stamford, CT), was injected in 5 mL aliquots to a total volume of 0.4 mL/kg (range, 25–35 mL). The needle position was considered acceptable if an evoked motor response of plantar flexion, inversion, eversion or a dorsiflexion of the ipsilateral foot was elicited at ≤0.4 mA. Complete block was defined as pinprick anesthesia and motor paralysis of the foot within 60 min. RESULTS: The median distance from the popliteal crease to the modified intertendinous site was 14.0 cm (interquartile range, 13.5–15 cm) compared to 7.5 cm (interquartile range 7.0–8.0 cm) for the classic posterior site (P < 0.01). Complete block was achieved in 44 of 55 patients (81.5%) in the modified intertendinous compared to 39 of 54 patients (70.9%) in the classic posterior group (P = 0.26). Complete block frequency was greater with an evoked motor response of inversion 49 of 56 patients (87.5%) and plantar flexion 23 of 30 patients (76.7%) compared with dorsiflexion/eversion 11 of 23 patients (47.8%) (P = 0.001). The median (95% CI) time (min) to complete block with an evoked motor response of inversion was 10 (0–22 min) for the modified intertendinous compared to 30 (4–56 min) with the classic posterior approach (P = 0.04). CONCLUSIONS: Potential advantages of the modified intertendinous approach include more rapid onset of anesthesia with an evoked motor response of inversion compared to a classic posterior popliteal sciatic nerve block.

Interscalene brachial plexus block: shoulder paresthesia versus deltoid motor response: revisiting the anatomy to settle the controversy.

In the original description of the interscalene technique of brachial plexus block (ISB), Winnie emphasized that only a paresthesia distal to the shoulder was acceptable to ensure successful block (1). This recommendation was based on the anatomical fact that a paresthesia to the shoulder itself might result from stimulation of the suprascapular nerve (C5 and C6 nerve roots), which may be within or outside the fascial sheath enclosing the brachial plexus roots, and hence, offers no guarantee of effecting successful shoulder anesthesia. By virtue of its objective evaluation of the nerves being stimulated, peripheral nerve stimulator (PNS) techniques have recently gained in popularity. Originally, Winnie’s recommendation of eliciting a distal paresthesia for ISB was extrapolated to include the PNS technique also, i.e., insisting on a motor response distal to the deltoid (biceps, triceps, or more distal musculature) (2–4). A study of Silverstein et al. (5) however, demonstrated that the deltoid motor response at the shoulder is equally efficacious. The apparent explanation is that the nerve supply to both the deltoid (axillary nerve) and biceps (musculocutaneous) originates from cervical nerve roots 5 and 6. If one were to revisit the anatomy of a shoulder paresthesia and that of a deltoid motor response, it would become readily apparent that those two end-points are not equivalent, even though the nerve roots (C5 and C6) responsible for mediating the two responses are identical (6). A shoulder paresthesia results from stimulation of the suprascapular nerve, which may be within or outside the fascial sheath, while a deltoid motor response results from stimulation of axillary nerve roots which lie within the fascial sheath. The sensory and motor elements of shoulder innervation essential for successful brachial plexus block, therefore, are clearly distinct and separate. Revisiting the anatomy supports Winnie’s original recommendation for seeking paresthesias distal to the shoulder when performing interscalene brachial plexus block by the paresthesia technique. On the other hand, when performing ISB using a PNS technique, a deltoid motor response is an appropriate end-point.