1、CIP critical illness polyneuropathyCIM critical illness myopathyCMAP compound muscl action potentialsSNAP sensory nerve action potentialEMG electromyogramSIRS systematic inflammatory response syndromeIn 1955 observed a polyneuropathy after shock or cardiac arrestIn 1961 described“coma-polyneuropathi
2、es”In 1971 described a polyneuropathy in patients with burnsin 1977 severe polyneuropathy about septic patientsBy 1983 the term“critical illness polyneuropathy”（CIP）was appliedRecently the termed“critical illness myopathy”（CIM）was appliedThe various factors associated with the SIRS CIP and CIM(Fig.1
3、)A simplified depiction of theoretical mechanisms of dysfunction in CIP and CIM.(Fig.2)Disorder of microcirculation（Fig.3)Adapted with permission from Bolton.Figure.1Adapted with permission fromBolton25.Figure.2 Figure.3 Schematic,theoretical presentation of disturbances in the microcirculation to v
4、arious organs,including brain,peripheral nerve,and muscle,in SIRS.Incidence 50%70%SIRS 20%50%ICU Weakness of limb and respiratory muscle Tendon reflexes absent or decrease Distal loss to pain,temperature,and vibrationClinical FeaturesThe diagnostic criteria for CIP are shown in following TableDiagno
5、sisDiagnostic criteria for CIPThe patient is critically ill(sepsis and multiple organ failure,SIRS)Difficulty weaning patient from ventilator afternonneuromuscular causes such as heart and lung diseasehave been excludedPossible limb weaknessElectrophysiologic evidence of axonal motor and sensory pol
6、yneuropathyDecline in the CMAP amplitude firstly(Fig.4)Dcline in the SNAP amplitudeMotor unit potentials may be reduced in numberSingle-fiber EMG indicate dysfunction of terminal motor axonsElectrophysiologic FeaturesFIG.4Peripheral axonal degeneration.Moderate loss of dorsal root ganglion cellsCent
7、ral chromatolysis of anterior horn cellsNo inflammation in the peripheral nervous systemMorphologic FeaturesMuscle biopsy Acute and chronic denervation Occasional myopathic changes Pathology of critical illness polyneuropathy.There is chromatolysis of anterior horn cells(A);(A);severe axonal degener
8、ation in this cross-section of superficial peripheral nerve(B)(B)and longitudinal section of deep peroneal nerve(C);(C);and acute and chronic denervation of intercostal muscle(D)(D)Axonal variants of GuillainBarre syndromeDevelop earlierOften associated with CJ infectionAbnormal cerebral spinal flui
9、dDifferential DiagnosisTransient neuromuscular blockade Repetitive nerve stimulation Measurement of anti-MuSK(muscle specific receptor tyrosine kinase)antibodiesTreatment of sepsis and multiple organ dysfunction syndrome Management of difficulty in weaning from the ventilator Attempts at direct trea
10、tment of CIP(still unproven)Physiotherapy and rehabilitationTreatment Two newer research approaches are being exploredIntensive insulin therapyThe administration of recombinant human activated protein C Recovery depends on the distanceRecovery for weeks in mild cases and months in severe casesSlowin
11、g of nerve conduction may have a poor prognosisPrognosisIncidenceAt least one-third of ICU patients（treated for status asthmaticus）In 7%of patients after transplantationClinical FeaturesClinical FeaturesMajor feature is flaccid weaknessTendon reflexes depressedOphthalmoplegia may be presentMyalgias
12、are uncommon Diagnostic criteria of CIM SNAP amplitudes 80%of the lower limit of normal Needle EMG with short-duration,low-amplitude MUPs with early or normal full recruitment,with or without fibrillation potentials Absence of a decremental response on repetitive nerve stimulationDiagnosis Muscle hi
13、stopathologic findings of myopathy with myosin loss CMAP amplitudes 80%of the lower limit of normal in two or more nerves without conduction block Elevated serum creatine kinase(CK）Demonstration of muscle inexcitability*For a definite diagnosis of critical illness myopathy,patients should have all o
14、f the first five features.Nerve conduction studiesLow-amplitude CMAPs Long duration CMAPsNormal SNAPsPhrenic nerve conduction normal latencies diaphragm CMAP amplitudes reduceElectrophysiologic FeaturesEMGFibrillation potentials and positive sharpMotor unit potentials low amplitude and short duratio
15、nElectrical inexcitability by direct needle stimulationFeatures of the histopathology in thick filament myosin loss(Fig.5)Electron microscopy reveals selective loss of thick(myosin)filaments(Fig.6)Inflammatory changes are conspicuously absent Morphologic Features Figure.5 Muscle histopathology in a
16、critically ill patient with thick filament myosin loss.(original magnification,100)(courtesy of Dr.Andrew Engel).Figure.6 Electron microscopy of muscle in CIM.(original magnification,44,000)(courtesy of Dr.Andrew Engel).CIPDirect needle stimulation of the muscle Electrical inexcitability in CIMThere
17、 is a response in CIP (Fig.7)Serum CKMuscle biopsyFIGURE.7FIGURE.7 Results of direct and indirect muscle stimulation.CMAPs from the anterior tibial muscles of a patient with critical illness polyneuropathy(left)and critical illness myopathy(right).Subtypes of CIMMuscle morphologicorphologicDifferentiating feature of neuromuscular disorders in critical illness Table 1.No specific therapy available as to nowPositioning to avoid additional nerve damage by pressureAvoid administering muscle relaxants and corticosteroidsTreatment
