Inability to consistently elicit a motor response following sensory paresthesia during interscalene block administration

BACKGROUND

Two methods of nerve block based on eliciting neural feedback with the block needle currently exist. The paresthesia technique uses sensory feedback to ascertain that the needle tip is close to the nerve. By contrast, a peripheral nerve stimulator makes use of motor responses to electrical stimulation. The relation of motor responses to an electrical peripheral nerve stimulator and sensory nerve contact (paresthesia) had not been studied.

METHODS

Thirty consecutive unpremedicated patients who presented for shoulder surgery with interscalene block anesthesia were prospectively studied. Interscalene block was performed by the single paresthesia method of Winnie, using an insulated or non-insulated needle connected to a peripheral nerve stimulator with the power off. At the precise point of paresthesia, the peripheral nerve stimulator was turned on, and the current was slowly increased to 1.0 mA with a pulse width of 0.2 ms. Presence and location of any motor responses were observed and recorded.

RESULTS

All patients had easily elicited paresthesias. The site of first paresthesia was to the shoulder in 73% of patients. Only 30% of patients exhibited any motor response to electrical stimulation up to 1.0 mA. There was no relation between site of paresthesia and associated motor nerve response.

CONCLUSION

Elicitation of paresthesia does not translate to an ability to elicit a motor response to a peripheral nerve stimulator in the majority of patients.

Murder misdiagnosed as SIDS: a perpetrator's perspective

AIMS

Child murder misdiagnosed as sudden infant death syndrome (SIDS) is a difficult area to study. We present a perpetrator's descriptions to enrich clinicians' knowledge of possible presenting features of this phenomenon.

METHODS

Interview material was collected as part of a qualitative study of maternal filicide performed from a naturalistic paradigm in order to access the perpetrators' view of events. The woman participant has been convicted for three child murders and two attempted murders which were initially misdiagnosed as SIDS. Interviews were done in the participant's home with her partner present, while she was on leave from prison. Semi-structured interviews were conducted, recorded, transcribed, and analysed for themes. Specific ethical permission was gained to present this case in isolation and the paper was written in consultation with the woman described.

RESULTS

She described initial intense attachment to her first victim and described killing her because she was unable to bear her apnoea attacks and her fear of losing her. She described difficulty grieving for this child and subsequent failure to attach to her next child or feel for the other victims.

CONCLUSIONS

Expressions of intense attachment to an infant and description of intense grief over a death in a way which engages compassion should not deter a paediatrician from considering the possibility of the parent having killed the child.

A nurse's aid to clinical selection of pressure-reducing equipment

The selection of appropriate pressure-relieving equipment for individuals in the community is an important process in the prevention of pressure ulcers. The clinical decision is made by community nurses who are accountable for their actions and who therefore have to have clear rationale for the decisions they make. Risk tools are not a completely reliable or valid method of assessing patients. The current national guidelines (National Institute for Clinical Excellence (NICE), 2001) are not specific in relation to the selection or choice of equipment. This article explores how these decisions are made.

A truly hybrid interventional MR/X-ray system: feasibility demonstration

A system enabling both x-ray fluoroscopy and MRI in a single exam, without requiring patient repositioning, would be a powerful tool for image-guided interventions. We studied the technical issues related to acquisition of x-ray images inside an open MRI system (GE Signa SP). The system includes a flat-panel x-ray detector (GE Medical Systems) placed under the patient bed, a fixed-anode x-ray tube overhead with the anode-cathode axis aligned with the main magnetic field and a high-frequency x-ray generator (Lunar Corp.). New challenges investigated related to: 1) deflection and defocusing of the electron beam of the x-ray tube; 2) proper functioning of the flat panel; 3) effects on B0 field homogeneity; and 4) additional RF noise in the MR images. We have acquired high-quality x-ray and MR images without repositioning the object using our hybrid system, which demonstrates the feasibility of this new configuration. Further work is required to ensure that the highest possible image quality is achieved with both MR and x-ray modalities.

A qualitative study of filicide by mentally ill mothers

OBJECTIVE

To examine descriptions of maternal filicide committed in the context of major mental illness from the frame of reference of a group of perpetrators.

METHOD

Participants were accessed via their treating psychiatrists. A naturalistic paradigm was used. Semi-structured individual interviews were audio-taped and transcribed. Theme analysis of the transcripts was done by repeated reading of transcripts and coding utterances, individually, then jointly by the authors.

RESULTS

Six women were identified, and interviewed. They described intense investment in mothering their child(ren). Descriptions of external stressors were not extreme, but the experience of illness was described as extremely stressful. They described little or no warning or planning. Their descriptions of their children were unremarkable. Motivation was described as altruistic or as an extension of suicide. They described regretting the killings and feeling responsible even though they knew they had been ill at the time.

CONCLUSIONS

The findings underline the difficulty of identification of risk and prevention of maternally ill filicide in the women who described being very caring towards their children, and little or no warning of filicidal urges. They may be better understood in terms of the illness than individual stress or psychodynamics.

Kinematics of the wrist. Evidence for two types of movement

We enrolled 34 normal volunteers to test the hypothesis that there were two types of movement of the wrist. On lateral radiographs two distinct patterns of movement emerged. Some volunteers showed extensive rotation of the lunate with a mean range of dorsiflexion of 65 degrees, while others had a mean range of 50 degrees. The extensive rotators were associated with a greater excursion of the centre of articulation of the wrist. It is suggested that dynamic external fixation of a fracture of the distal radius carries with it the risk of stretching the ligaments or causing volar displacement at the site of the fracture.

Double-blind randomized controlled trial of glutamine-enriched polymeric diet in the treatment of active Crohn's disease

BACKGROUND

Glutamine is traditionally considered a nonessential amino acid but may be conditionally essential in patients with catabolic conditions. Glutamine-supplemented foods in these patients have been shown to prevent deterioration of gut permeability, protect against the development of intestinal mucosal atrophy, and improve nitrogen balance. Animal models of inflammatory bowel disease suggest that glutamine-enriched enteral diets may lead to less severe intestinal damage, less weight loss, improved nitrogen balance, and reduced disease activity. The purpose of the current study was to compare the efficacy of a glutamine-enriched polymeric diet with a standard low-glutamine polymeric diet in the treatment of active Crohn's disease.

METHODS

Eighteen children with active Crohn's disease were randomly assigned to receive a 4-week course of either a standard polymeric diet with a low glutamine content (4% of amino acid composition; group S) or a glutamine-enriched polymeric diet (42% of amino acid composition; Group G). The two diets were isocaloric and isonitrogenous with an identical essential amino acid profile. Remission rates were analysed on an intent-to-treat basis. Changes in clinical and laboratory parameters of disease activity were also compared after 4 weeks of nutritional treatment.

RESULTS

Two of the children, both in group G, were withdrawn from the trial because of nontolerance of the diet. There was no difference between the two groups in proportion of patients achieving remission (intent-to-treat basis): 5 (55.5%) of 9 in group S versus 4 (44.4%) of 9 in group G (p = 0.5). Improvement in mean paediatric Crohn's disease activity index (PCDAI) was significantly more in group S (p = 0.002) but changes in orosomucoid level, platelet count, and weight were not different between the groups.

CONCLUSIONS

The findings suggest that a glutamine-enriched polymeric diet offers no advantage over a standard low-glutamine polymeric diet in the treatment of active Crohn's disease. Rather, it appears to be less effective in improving PCDAI. The reported beneficial effects of glutamine seen in many catabolic states must be viewed with caution when extrapolating to the management of Crohn's disease.

The cost of living: kidney dialysis, rationing and health economics in Britain, 1965-1996

How important is research in shaping policy when a new life-saving medical technology becomes available, but happens to be very expensive? Taking the case of kidney dialysis, this paper argues that the emerging discipline of health economics had little influence relative to national differences in health service organization and cultures of expectation of provision. Paradoxically, the most effective covert rationing was achieved under the British NHS which ostensibly provides free care for all, while the uncentralised market system in the US gave way, on this issue, to almost universal state-subsidised provision. Under the British system, the most cost-effective options for renal care tended to flourish, but some patients were turned away. Physicians have been held responsible for complying with covert rationing: this paper suggests that early gearing towards socially-useful survival filtered back to selection at primary level, possibly continuing long after specialists wished to expand. Public outcry, though muted, reached parliament and caused minor shifts in policy; the main aim of the voluntary pressure campaign, to release more organs for transplant through 'opt-out', remained unrealised in the UK. Yet dialysis was targetted for expansion in the 1980s just at the point when health economists were presenting evidence for its low cost-effectiveness compared with other expensive interventions. According to the main strand of argument in this paper, comparisons with other countries and between regions were most influential in breaking the hold of covert rationing: policy making by embarrassment. However, in the 1990s, there are both theoretical discussions of explicit rationing, and open intiatives afoot to target dialysis for rationing.

Reticulate evolution and the origins of ribosomal internal transcribed spacer diversity in apomictic Meloidogyne

Among root knot nematodes of the genus Meloidogyne, the polyploid obligate mitotic parthenogens M. arenaria, M. javanica, and M. incognita are widespread and common agricultural pests. Although these named forms are distinguishable by closely related mitochondrial DNA (mtDNA) haplotypes, detailed sequence analyses of internal transcribed spacers (ITSs) of nuclear ribosomal genes reveal extremely high diversity, even within individual nematodes. This ITS diversity is broadly structured into two very different groups that are 12%-18% divergent: one with low diversity (< 1.0%) and one with high diversity (6%-7%). In both of these groups, identical sequences can be found within individual nematodes of different mtDNA haplotypes (i.e., among species). Analysis of genetic variance indicates that more than 90% of ITS diversity can be found within an individual nematode, with small but statistically significant (5%-10%; P < 0.05) variance distributed among mtDNA lineages. The evolutionarily distinct parthenogen M. hapla shows a similar pattern of ITS diversity, with two divergent groups of ITSs within each individual. In contrast, two diploid amphimictic species have only one lineage of ITSs with low diversity (< 0.2%). The presence of divergent lineages of rDNA in the apomictic taxa is unlikely to be due to differences among pseudogenes. Instead, we suggest that the diversity of ITSs in M. arenaria, M. javanica, and M. incognita is due to hybrid origins from closely related females (as inferred from mtDNA) and combinations of more diverse paternal lineages.

APOE is linked to Alzheimer's disease in a large pedigree

Although previous association studies have demonstrated that the APOE4 allele is a risk factor for Alzheimer's disease (AD), its value for the prediction of AD in individuals is <100%. The limited predictive value of epsilon4 is also seen in multiply affected families where the epsilon4 allele is not tightly linked to AD. We analyzed a large pedigree multiply affected with AD by lod score linkage analysis at the known loci associated with AD. In this pedigree, the APOE/APOCI gene area was linked to the development of AD, while no linkage was detected to any of the other loci known to be associated with the disease. In this family, then, the inheritance of an epsilon4 allele is highly associated with the early development of the disease (mean age of onset, 62 years), and is a good predictor of disease. However, given the wealth of evidence for association, but not linkage, of APOE4 to AD, we believe this finding suggests that another factor (or factors) interact(s) with APOE to precipitate early disease, and produce positive linkage results. The nature of this factor presently remains unknown.

No association between the intronic presenilin-1 polymorphism and Alzheimer's disease in clinic and population-based samples

Mutations in the Presenilin 1 (PS1) gene on chromosome 14 cause most early-onset familial Alzheimer's disease (AD). An intronic polymorphism in the PS1 gene was recently identified and reported to be associated with late-onset AD [Wragg et al., Lancet 347: 509-512, 1996]. The authors found an excess of homozygotes for the more common allele (allele 1) in AD cases, associated with an approximate doubling of risk. In the present study, we report the PS1 polymorphism distributions in clinic and population-based samples. We were not able to replicate the findings of Wragg et al. [1996]. Our results are consistent with those of other researchers and do not support the conclusion that the PS1 polymorphism is associated with late-onset AD.

The direction of the Whitacre needle aperture affects the extent and duration of isobaric spinal anesthesia

The use of Whitacre spinal needles results in directional flow out of the needle aperture, diverting local anesthetic from the longitudinal axis of the needle. Thus, a change in orientation of the needle aperture would be expected to result in a different local anesthetic distribution in the subarachnoid space. We studied 40 outpatients undergoing elective knee arthroscopy under spinal anesthesia with 60 mg plain lidocaine 2% in a prospective, double-blinded manner. Patients were randomly assigned to either Group I (needle aperture oriented in a cephalad direction throughout intrathecal injection) or Group II (aperture directed caudally). Onset and offset of sensory and motor block were analyzed at frequent intervals. Times to completion of ambulatory milestones, including discharge, were recorded. Group I was characterized by a higher sensory level (T 3.4 +/- 1.3 vs T 6.6 +/- 2.8, P < 0.001). Group I had significantly shorter duration of lumbar sensory anesthesia (149.2 +/- 30.6 min vs 177.8 +/- 23.5 min, P < 0.01) and motor blockade (117.6 +/- 26.1 min vs 150.0 +/- 22.8 min, P < 0.001). Mean time to outpatient discharge was approximately 32 min shorter in Group I. The orientation of the Whitacre needle aperture exerts a major influence on sensory level, as well as the duration of isobaric lidocaine spinal anesthesia.

Evolution of the AT-rich mitochondrial DNA of the root knot nematode, Meloidogyne hapla

Mitochondrial DNA of the root knot nematode Meloidogyne hapla was investigated for intraspecific diversity and divergence from other parthenogenetic root knot nematodes. A 1,900-bp fragment containing COII, tRNAHis, 16S rRNA, ND3 and Cyt b genes has been cloned and sequenced from one individual and an 1,188-bp region within this region was sequenced from four other Australian isolates. M. hapla mtDNA is more than 80% AT-rich, like other Meloidogyne spp. Nucleotide diversity within M. hapla is some 10-fold higher than across three other parthenogenetic species of root-knot nematode (M. arenaria, M. javanica, and M. incognita), implying an earlier origin for M. hapla. Nucleotide divergence between M. hapla and its congener M. javanica is as great as that between Ascaris suum and Caenorhabditis elegans, members of different nematode subclasses, while amino acid sequence difference between Meloidogyne is more than twice as great. This is interpreted as an AT-bias-induced acceleration of the amino acid substitution rate, over and above saturation of nucleotide divergence in the strongly AT-biased DNA, on three lines of evidence: (1) in conserved blocks in 16S rDNA congeneric Meloidogyne have no more differences than between A. suum and C. elegans; (2) the Meloidogyne lineage has more amino acid changes relative to the Ascaris/Caenorhabditis lineage with respect to four of five outgroups, the exceptional outgroup being the only species (Apis) as AT-rich as Meloidogyne; and (3) between the two Meloidogyne there are more first and second but fewer third codon position changes than between the other nematode species. M. hapla is also found to contain a 102-bp tandem repeat of at least 40 copies; a size, arrangement, and position the same as in M. javanica, but sequence comparisons did not demonstrate homology between the two repeats.

Digital pressure during interscalene block is clinically ineffective in preventing anesthetic spread to the cervical plexus

The application of digital pressure above the injection site during interscalene block has been advocated to prevent cephalad spread of local anesthetic. In prior studies, radiographs taken immediately after interscalene injection of radiographic contrast have supported this concept. However, the clinical efficacy of digital pressure has not been previously tested. If digital pressure were effective in inhibiting cephalad spread of local anesthetic, attenuation of both hemidiaphragmatic paresis and the resulting compromise in pulmonary function would be expected. Sensory, motor, and pulmonary effects were prospectively evaluated in 20 patients presenting for elective shoulder surgery. Patients were randomly assigned to receive interscalene block with or without digital pressure. No clinical differences were seen between groups. All 20 patients had ipsilateral hemidiaphragmatic paresis by ultrasonographic evaluation and large mean decreases in forced vital capacity, 31.2% +/- 7.8% (with digital pressure), 33.7% +/- 12.8% (without digital pressure), and forced expiratory volume at one second, 27.9% +/- 9.3% (with digital pressure), 33.7 +/- 12.8% (without digital pressure). Peak sensory level of anesthesia to pinprick was not significantly different between groups, each group having mean levels of C-2 to C-3. Digital pressure was ineffective in limiting the flow of local anesthetic into the cervical plexus. Digital pressure influenced neither the incidence of diaphragmatic paresis nor the resulting large decreases in pulmonary function that result from interscalene block.

Combined spinal-epidural anesthesia for outpatient surgery. Dose-response characteristics of intrathecal isobaric lidocaine using a 27-gauge Whitacre spinal needle

BACKGROUND

Combined spinal-epidural anesthesia (CSE) may offer theoretic advantages for outpatient surgery, because it produces the rapid onset of spinal anesthesia, with the option to extend the blockade with an epidural catheter. In this study, the authors attempted to determine an appropriate initial dose of a short-acting local anesthetic, 2% lidocaine, to administer for outpatient knee arthroscopy using CSE.

METHODS

Data were collected from 90 patients undergoing outpatient knee arthroscopy. Using a double-blinded, prospective study design, patients were randomly assigned to receive CSE with an initial dose of intrathecal 2% lidocaine of 40, 60, or 80 mg. A 27-G 4 11/16-inch Whitacre needle was placed through a 17-G Weiss needle. Onset and regression of sensory anesthesia and motor blockade were measured by a blinded observer at frequent intervals.

RESULTS

All 90 patients had adequate anesthesia. Durations of thoracic and lumbar sensory and lower limb motor blockade were significantly shorter in the 40-mg group compared with the 60- or 80-mg groups (P < 0.0002 Mantel-Cox, Survivorship Analysis). Indices of neural blockade resolved 30-40 min more rapidly in the 40-mg group than in either the 60- or 80-mg group. Times to urinate, site upright in a chair, take oral fluids, and be discharged were all significantly shorter (between 30 and 60 min) in the 40-mg group compared with the 60- and 80-mg groups (P < 0.01). Seven patients required intraoperative epidural supplementation: three in the 40-mg group, three in the 60-mg group, and one in the 80-mg group.

CONCLUSIONS

Combined spinal-epidural anesthesia with a 40-mg initial intrathecal dose of lidocaine provided reliable anesthesia for knee arthroscopy. Duration of spinal anesthesia with lidocaine was dose related.