Introduction: The current literature on the use of real-time ultrasound-guidance for lumbar punctures (LP) is limited. Two techniques have been described: the paramedian sagittal oblique (PSO); and the transverse interlaminar (TL) approach. Our objectives in this study were to compare the procedure outcomes between these two techniques and assess the ability of emergency physicians to perform ultrasound-guided LPs.

Methods: This was a prospective study whose participants included emergency physicians. Participants were randomized into either Group P (PSO technique) or Group T (TL technique). After a didactic session, participants then performed an ultrasound-guided LP on a training manikin, during which we collected procedure data. A survey was administered after completion of the procedure. 

Results: A total of 31 participants were included, 16 in Group P and 15 in Group T. Most participants (90.3%) successfully performed the procedure, without a statistical difference between Group P and Group T (15/16 vs 13/15, P = 0.95). Group T required a longer average time to complete the procedure (176.7 ± 140.4 seconds [s] vs 311.2 ± 202.3 s, P = 0.04). There was no statistically significant difference between Group P and Group T with regard to average time needed to obtain the required ultrasound view (18.3 ± 14.6 s vs 35.1 ± 32.9 s, P = 0.09); number of needle redirections; total number of needle passes; first puncture success; number of participants who advanced the needle without visualization of the tip (13/16 vs 14/15, P = 0.64); penetration of the anterior dura; and needle contact with bone. The Likert-style questionnaire responses (reported on a 1-10 scale) revealed no difference between Group P and Group T as to perceived difficulty of finding the required ultrasound view (3 [interquartile range (IQR) 2-5) vs 5 (IQR 3-6.5), P = 0.10), perceived difficulty of needle tracking, or rating of the needle view when entering the intrathecal space. However, Group T reported a higher overall perceived level of difficulty (4 [IQR 3-5] vs 6 (IQR 5.5-7.5), P= 0.01). 

Conclusion: This study suggests emergency physicians can be trained to use ultrasound-guidance for lumbar puncture in the simulation setting without significantly prohibitive training. Both techniques were performed with high success rates. There may be a preference for implementing the paramedian sagittal oblique approach over the transverse interlaminar.

Chronic neuropathic pain may be caused, in part, by loss of inhibition in spinal pain processing pathways due to attenuation of local GABAergic tone. Nociception and nocifensive behaviors are reduced after enhancement of tonically activated extrasynaptic GABAAR-mediated currents by agonist ligands for δ subunit-containing GABAARs. However, typical ligands that target δ subunit-containing GABAARs are limited due to sedative effects at higher doses. We used the spinal nerve ligation (SNL) and gp120 models of experimental neuropathic pain to evaluate compound 2-261, a nonbenzodiazepine site positive allosteric modulator of α4β3δ GABAARs optimized to be nonsedative by selective activation of β2/3-subunit-containing GABAARs over receptor subtypes incorporating β1 subunits. Similar levels of 2-261 were detected in the brain and plasma after intraperitoneal administration. Although systemic 2-261 did not alter sensory thresholds in sham-operated animals, it significantly reversed SNL-induced thermal and tactile hypersensitivity in a GABAAR-dependent fashion. Intrathecal 2-261 produced conditioned place preference and elevated dopamine levels in the nucleus accumbens of nerve-injured, but not sham-operated, rats. In addition, systemic pretreatment with 2-261 blocked conditioned place preference from spinal clonidine in SNL rats. Moreover, 2-261 reversed thermal hyperalgesia and partially reversed tactile allodynia in the gp120 model of HIV-related neuropathic pain. The effects of 2-261 likely required interaction with the α4β3δ GABAAR because 2-301, a close structural analog of 2-261 with limited extrasynaptic receptor efficacy, was not active. Thus, 2-261 may produce pain relief with diminished side effects through selective modulation of β2/3-subunit-containing extrasynaptic GABAARs.