Werner Josef Z'Graggen

Decompressive Hemicraniectomy in Patients With Supratentorial Intracerebral Hemorrhage

Background and Purpose— Decompressive craniectomy (DC) lowers intracranial pressure and improves outcome in patients with malignant middle cerebral artery stroke. Its usefulness in intracerebral hemorrhage (ICH) is unclear. The aim of this study was to analyze feasibility and safety of DC without clot evacuation in ICH. Methods— We compared consecutive patients (November 2010–January 2012) with supratentorial ICH treated with DC without hematoma evacuation and matched controls treated by best medical treatment. DC measured at least 150mm and included opening of the dura. We analyzed clinical (age, sex, pathogenesis, Glasgow Coma Scale, National Institutes of Health Stroke Scale), radiological (signs of herniation, side and size of hematoma, midline shift, hematoma expansion, distance to surface), and surgical (time to and indication for surgery) characteristics. Outcome at 6 months was dichotomized into good (modified Rankin Scale 0–4) and poor (modified Rankin Scale 5–6). Results— Twelve patients (median age 48 years; interquartile range 35–58) with ICH were treated by DC. Median hematoma volume was 61.3mL (interquartile range 37–83.5mL) and median preoperative Glasgow Coma Scale was 8 (interquartile range 4.3–10). Four patients showed signs of herniation. Nine patients had good and 3 had poor outcomes. Three patients (25%) of the treatment group died versus 8 of 15 (53%) of the control group. There were 3 manageable complications related to DC. Conclusions— DC is feasible in patients with ICH. Based on this small cohort, DC may reduce mortality. Larger prospective cohorts are warranted to assess safety and efficacy.

VELOCITY RECOVERY CYCLES OF HUMAN MUSCLE ACTION POTENTIALS AND THEIR SENSITIVITY TO ISCHEMIA

This study was undertaken to test whether recovery cycle measurements can provide useful information about the membrane potential of human muscle fibers. Multifiber responses to direct muscle stimulation through needle electrodes were recorded from the brachioradialis of healthy volunteers, and the latency changes measured as conditioning stimuli were applied at interstimulus intervals of 2–1000 ms. In all subjects, the relative refractory period (RRP), which lasted 3.27 ± 0.45 ms (mean ± SD, n = 12), was followed by a phase of supernormality, in which the velocity increased by 9.3 ± 3.4% at 6.1 ± 1.3 ms, and recovered over 1 s. A broad hump of additional supernormality was seen at around 100 ms. Extra conditioning stimuli had little effect on the early supernormality but increased the later component. The two phases of supernormality resembled early and late afterpotentials, attributable respectively to the passive decay of membrane charge and potassium accumulation in the t‐tubules. Five minutes of ischemia progressively prolonged the RRP and reduced supernormality, confirming that these parameters are sensitive to membrane depolarization. Velocity recovery cycles may provide useful information about altered muscle membrane potential and t‐tubule function in muscle disease. Muscle Nerve, 2008

Muscle membrane dysfunction in critical illness myopathy assessed by velocity recovery cycles

OBJECTIVE To test the hypothesis that muscle fibers are depolarized in patients with critical illness myopathy by measuring velocity recovery cycles (VRCs) of muscle action potentials. METHODS VRCs were recorded from brachioradialis muscle by direct muscle stimulation in 10 patients in intensive care with evidence of critical illness myopathy (CIM). Two sets of recordings were made, mean 3.9 d apart, and compared with those from 10 age-matched controls. RESULTS Muscle supernormality was reduced in the patients by 50% compared with controls (P<0.002) and relative refractory period was increased by 59% (P<0.01). Supernormality was correlated with plasma potassium levels (R=-0.753, P<0.001), and the slope of this relationship was much steeper than previously reported for non-critically ill patients with renal failure (P<0.01). CONCLUSIONS The abnormal excitability properties indicate that the muscle fibers in CIM were depolarized, and/or that sodium channel inactivation was increased. The heightened sensitivity to potassium is consistent with the hypothesis that an endotoxin reduces sodium channel availability in depolarized muscle fibers. SIGNIFICANCE VRCs provide a practicable means to monitor muscle membrane changes in intensive care and to investigate the pathogenesis of CIM.

Spinal cerebrospinal fluid leak as the cause of chronic subdural hematomas in nongeriatric patients

OBJECT The etiology of chronic subdural hematoma (CSDH) in nongeriatric patients (≤ 60 years old) often remains unclear. The primary objective of this study was to identify spinal CSF leaks in young patients, after formulating the hypothesis that spinal CSF leaks are causally related to CSDH. METHODS All consecutive patients 60 years of age or younger who underwent operations for CSDH between September 2009 and April 2011 at Bern University Hospital were included in this prospective cohort study. The patient workup included an extended search for a spinal CSF leak using a systematic algorithm: MRI of the spinal axis with or without intrathecal contrast application, myelography/fluoroscopy, and postmyelography CT. Spinal pathologies were classified according to direct proof of CSF outflow from the intrathecal to the extrathecal space, presence of extrathecal fluid accumulation, presence of spinal meningeal cysts, or no pathological findings. The primary outcome was proof of a CSF leak. RESULTS Twenty-seven patients, with a mean age of 49.6 ± 9.2 years, underwent operations for CSDH. Hematomas were unilateral in 20 patients and bilateral in 7 patients. In 7 (25.9%) of 27 patients, spinal CSF leakage was proven, in 9 patients (33.3%) spinal meningeal cysts in the cervicothoracic region were found, and 3 patients (11.1%) had spinal cysts in the sacral region. The remaining 8 patients (29.6%) showed no pathological findings. CONCLUSIONS The direct proof of spinal CSF leakage in 25.9% of patients suggests that spinal CSF leaks may be a frequent cause of nongeriatric CSDH.

Quantification of central motor conduction deficits in multiple sclerosis patients before and after treatment of acute exacerbation by methylprednisolone

Objective: To compare the effects of intravenous methylprednisolone (IVMP) in patients with relapsing-remitting (RR-MS), secondary progressive (SP-MS), and primary progressive multiple sclerosis (PP-MS). Methods: Clinical and neurophysiological follow up was undertaken in 24 RR-MS, eight SP-MS, and nine PP-MS patients receiving Solu-Medrol 500 mg/d over five days for exacerbations involving the motor system. Motor evoked potentials (MEPs) were used to measure central motor conduction time (CMCT) and the triple stimulation technique (TST) was applied to assess conduction deficits. The TST allows accurate quantification of the number of conducting central motor neurones, expressed by the TST amplitude ratio. Results: There was a significant increase in TST amplitude ratio in RR-MS (p<0.001) and SP-MS patients (p<0.02) at day 5, paralleling an increase in muscle force. TST amplitude ratio and muscle force remained stable at two months. In PP-MS, TST amplitude ratio and muscle force did not change. CMCT did not change significantly in any of the three groups. Conclusions: In RR-MS and SP-MS, IVMP is followed by a prompt increase in conducting central motor neurones paralleled by improvement in muscle force, which most probably reflects partial resolution of central conduction block. The lack of similar clinical and neurophysiological changes in PP-MS corroborates previous clinical reports on limited IVMP efficacy in this patient group and points to pathophysiological differences underlying exacerbations in PP-MS.

Weakness on the intensive care unit

Patients who are recovering from critical illness may be weak and difficult to wean from ventilatory support as a complication of their underlying disorder, intercurrent events or treatment given during prolonged intensive care. These patients are difficult to assess because of the severity of their weakness and any accompanying encephalopathy. It is essential to undertake a meticulous review, including assessment of any septic, hypoxic or metabolic derangements and a detailed look at the dosage and duration of medication including antibiotics, neuromuscular junction blocking agents and sedation. If a primary underlying neurological cause or an intercurrent event have been excluded, the likeliest cause of weakness is one of the neuromuscular complications of critical care such as: critical care polyneuropathy, an acute axonal neuropathy which develops in patients with preceding sepsis or multi-organ failure; the use of neuromuscular junction blocking agents or steroids; and critical illness myopathy, which is the most common cause of critical care related weakness.

Repetitive spinal motor neuron discharges following single transcranial magnetic stimuli: a quantitative study.

OBJECTIVE To quantify repetitive discharges of spinal motor neurons (repMNDs) in response to single transcranial magnetic stimuli (TMS). To assess their contribution to the size of motor evoked potentials (MEPs). METHODS We combined the triple stimulation technique (TST) with an additional nerve stimulus in the periphery (= quadruple stimulation; QuadS). The QuadS eliminates the first action potential descending on each axon after TMS, and eliminates effects on response size induced by desynchronization of these discharges, thereby allowing a quantification of motor neurons (MNs) discharging twice. In some instances, a quintuple stimulation (QuintS) was used, to quantify the number of MNs discharging three times. Recordings were from the abductor digiti minimi of 14 healthy subjects, using two different stimulation intensities and three different levels of facilitatory muscle pre-contractions. RESULTS The threshold to obtain repMNDs was high. Their maximal size differed markedly between subjects, ranging from 8 to 52% of all MNs. Stimulation intensity and facilitatory muscle contraction, but not resting motor threshold, correlated with the amount of repMNDs. QuintS never yielded discernible responses, hence all observed repMNDs were double discharges. RepMNDs contributed to the MEP areas, but did not influence MEP amplitudes. CONCLUSIONS QuadS and QuintS allow precise quantification of repMNDs. The threshold of repMNDs is high and varies considerably between subjects. SIGNIFICANCE repMNDs have to be considered when MEP areas are measured. Their analysis may be of interest in neurological disorders, but standardized stimulation parameters appear essential.

Dysfunction of respiratory muscles in critically ill patients on the intensive care unit.

Muscular weakness and muscle wasting may often be observed in critically ill patients on intensive care units (ICUs) and may present as failure to wean from mechanical ventilation. Importantly, mounting data demonstrate that mechanical ventilation itself may induce progressive dysfunction of the main respiratory muscle, i.e. the diaphragm. The respective condition was termed ‘ventilator‐induced diaphragmatic dysfunction’ (VIDD) and should be distinguished from peripheral muscular weakness as observed in ‘ICU‐acquired weakness (ICU‐AW)’.

Membrane dysfunction in Andersen‐Tawil syndrome assessed by velocity recovery cycles

Introduction: Andersen‐Tawil syndrome (ATS) due to Kir2.1mutations typically manifests as periodic paralysis, cardiac arrhythmias and developmental abnormalities but is often difficult to diagnose clinically. This study was undertaken to determine whether sarcolemmal dysfunction could be identified with muscle velocity recovery cycles (MVRCs). Methods: Eleven genetically confirmed ATS patients and 20 normal controls were studied. MVRCs were recorded with 1, 2, and 5 conditioning stimuli and with single conditioning stimuli during intermittent repetitive stimulation at 20 Hz, in addition to the long exercise test. Results: ATS patients had longer relative refractory periods (P < 0.0001) and less early supernormality, consistent with membrane depolarization. Patients had reduced enhancement of late supernormality with 5 conditioning stimuli (P < 0.0001), and less latency reduction during repetitive stimulation (P < 0.001). Patients were separated completely from controls by combining MVRC and repetitive stimulation. Conclusions: MVRCs combined with repetitive stimulation differentiated ATS patients from controls more effectively than the conventional long‐exercise test. Muscle Nerve 46: 193–203, 2012

Diskogenic microspurs as a major cause of intractable spontaneous intracranial hypotension

Objective: To visualize and treat spinal dural CSF leaks in all patients with intractable spontaneous intracranial hypotension (SIH) who underwent spinal microsurgical exploration. Methods: Patients presenting between February 2013 and July 2015 were included in this consecutive case series. The workup included spinal MRI without and with intrathecal contrast, dynamic myelography, postmyelography CT, and microsurgical exploration. Results: Of 69 consecutive patients, 15 had intractable symptoms. Systematic imaging revealed a suspicious single location of the leak in these 15 patients. Fourteen patients underwent microsurgical exploration; 1 patient refused surgery. Intraoperatively, including intradural exploration, we identified the cause of the CSF leaks as a longitudinal dural slit (6.1 ± 1.7 mm) on the ventral (10), lateral (3), or dorsal (1) aspect of the dura. In 10 patients (71%), a ventral, calcified microspur originating from the intervertebral disk perforated the dura like a knife. Three patients (22%) had a lateral dural tear with an associated spinal meningeal diverticulum, and in 1 patient (7%), a dorsal osteophyte was causal. The microspurs were removed and the dural slits sutured with immediate cessation of CSF leakage. Conclusion: The nature of the CSF leak is a circumscribed longitudinal slit at the ventral, lateral, or dorsal dura mater. An extradural pathology, diskogenic microspurs, was the single cause for all ventral CSF leaks. These findings challenge the notion that CSF leaks in SIH are idiopathic or due to a weak dura. Microsurgery is the treatment of choice in cases with intractable SIH.