Co-existence of anti-glutamic acid decarboxylase-65 and anti-sry-like high-mobility group box receptor antibody-associated autoimmune encephalitis: A rare case report.

Autoimmune encephalitis (AE) has been increasingly recognized in children. An 11-year-old Saudi boy presented with prodromal symptoms of fever and headache followed by behavioral changes, cognitive impairment, and focal seizures. Cerebrospinal fluid (CSF) analysis showed pleocytosis. Brain magnetic resonance imaging showed T2/fluid-attenuated inversion recovery hyperintensities involving the temporal, parietal and frontal lobes. Electroencephalography revealed diffuse encephalopathy and electrographic seizures. AE was suspected; intravenous methylprednisolone and immunoglobulin were administered. Autoantibodies against glutamic acid decarboxylase-65 were detected in his serum and CSF and against Sry-like high- mobility group box 1 in his serum only. The patient was diagnosed with seropositive AE and favorably responded to intensive immunosuppressive therapy.

Intraoperative direct cortical stimulation motor evoked potentials: Stimulus parameter recommendations based on rheobase and chronaxie.

OBJECTIVE: To determine optimal interstimulus interval (ISI) and pulse duration (D) for direct cortical stimulation (DCS) motor evoked potentials (MEPs) based on rheobase and chronaxie derived with two techniques. METHODS: In 20 patients under propofol/remifentanil anesthesia, 5-pulse DCS thenar MEP rheobase and chronaxie with 2, 3, 4 and 5ms ISI were measured by linear regression of five charge thresholds at 0.05, 0.1, 0.2, 0.5 and 1msD, and estimated from two charge thresholds at 0.1 and 1msD using simple arithmetic. Optimal parameters were defined by minimum threshold energy: the ISI with lowest rheobase2×chronaxie, and D at its chronaxie. Near-optimal was defined as threshold energy <25% above minimum. RESULTS: The optimal ISI was 3 or 4 (n=7 each), 2 (n=4), or 5ms (n=2), but only 4ms was always either optimal or near-optimal. The optimal D was ∼0.2 (n=12), ∼0.1 (n=7) or ∼0.3ms (n=1). Two-point estimates closely approximated five-point measurements. CONCLUSIONS: Optimal ISI/D varies, with 4ms/0.2ms being most consistently optimal or near-optimal. Two-point estimation is sufficiently accurate. SIGNIFICANCE: The results endorse 4ms ISI and 0.2msD for general use. Two-point estimation could enable quick individual optimization.

Utility of motor evoked potentials for intraoperative nerve root monitoring.

There is no entirely satisfactory way to monitor nerve root integrity during spinal surgery. In particular, standard free-running electromyography carries a high false-positive rate and some false-negative rate of injury. Stimulated electromyography to direct root stimulation can only be done intermittently, and roots are often inaccessible. This article reviews to what extent muscle motor evoked potential (MEP) monitoring might help. It presents background considerations, describes MEP methodology, and summarizes relevant experimental animal and clinical studies. Based on current evidence, root compromise can cause myotomal MEP deterioration that in some cases may be reversible. However, because of radicular overlap, limited sampling, confounding factors, and response variability, the effects range from no appreciable change to variable degrees of amplitude reduction to disappearance and some false-positive and false-negative results should be expected. For root monitoring, multichannel MEP recordings should span adjacent myotomes and avoid mixed myotome derivations. Only amplitude reduction warning criteria have been studied, but no percentage cutoff consensus has emerged, and this approach is troubled by response variability. There is some evidence that MEPs might reduce false electromyographic results. In conclusion, muscle MEPs could compliment electromyography but seem unlikely to completely solve the problem of nerve root monitoring.