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1、CRITICAL ILLNESS NEUROMYOPATHY,Abbreviations,CIP critical illness polyneuropathyCIM critical illness myopathyCMAP compound muscl action potentialsSNAP sensory nerve action potentialEMG electromyogramSIRS systematic inflammatory response syndrome,HISTORICAL REVIEW,In 1955 observed a polyneuropathy af
2、ter shock or cardiac arrestIn 1961 described “coma-polyneuropathies” In 1971 described a polyneuropathy in patients with burnsin 1977 severe polyneuropathy about septic patients,By 1983 the term “critical illness polyneuropathy”（CIP） was appliedRecently the termed “critical illness myopathy ”（CIM） w
3、as applied,Studies about Aetiologyvariously,The various factors associated with the SIRS CIP and CIM (Fig. 1) 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. 1,Adapted with permi
4、ssion fromBolton25.,Figure. 2,Figure.3 Schematic, theoretical presentation of disturbances in the microcirculation to various 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 D
5、istal loss to pain, temperature, and vibration,Clinical Features,The diagnostic criteria for CIP are shown in following Table,Diagnosis,Diagnostic criteria for CIPThe patient is critically ill (sepsis and multiple organ failure,SIRS)Difficulty weaning patient from ventilator afternonneuromuscular ca
6、uses such as heart and lung diseasehave been excludedPossible limb weaknessElectrophysiologic evidence of axonal motor and sensory polyneuropathy,Decline in the CMAP amplitude firstly (Fig. 4)Dcline in the SNAP amplitudeMotor unit potentials may be reduced in numberSingle-fiber EMG indicate dysfunct
7、ion of terminal motor axons,Electrophysiologic Features,Measurement of compound thenar muscle action potentials at the onset of sepsis (A) and 3 weeks later (B).,FIG.4,Peripheral axonal degeneration.Moderate loss of dorsal root ganglion cellsCentral chromatolysis of anterior horn cellsNo inflammatio
8、n in the peripheral nervous system,Morphologic Features,Muscle biopsy Acute and chronic denervation Occasional myopathic changes,Pathology of critical illness polyneuropathy. There is chromatolysis of anterior horn cells (A); severe axonal degeneration in this cross-section of superficial peripheral
9、 nerve (B) and longitudinal section of deep peroneal nerve (C); and acute and chronic denervation of intercostal muscle (D),Axonal variants of GuillainBarre syndromeDevelop earlierOften associated with CJ infectionAbnormal cerebral spinal fluid,Differential Diagnosis,Transient neuromuscular blockade
10、Repetitive nerve stimulationMeasurement of anti-MuSK (muscle specific receptor tyrosine kinase) antibodies,Treatment of sepsis and multiple organ dysfunction syndrome Management of difficulty in weaning from the ventilator Attempts at direct treatment of CIP (still unproven) Physiotherapy and rehabi
11、litation,Treatment,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 casesSlowing of nerve conduction may have a poor prognosis,Pro
12、gnosis,IncidenceAt least one-third of ICU patients（ treated for status asthmaticus）In 7% of patients after transplantation,Clinical FeaturesMajor feature is flaccid weaknessTendon reflexes depressedOphthalmoplegia may be presentMyalgias are uncommon,Diagnostic criteria of CIM SNAP amplitudes 80% of
13、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 stimulation,Diagnosis, Muscle histopathologic findings of myopathy with myosin loss CMAP a
14、mplitudes 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 of the first five features.,Nerve conduction studiesLow
15、-amplitude CMAPs Long duration CMAPsNormal SNAPsPhrenic nerve conduction normal latencies diaphragm CMAP amplitudes reduce,Electrophysiologic Features,EMGFibrillation potentials and positive sharpMotor unit potentials low amplitude and short durationElectrical inexcitability by direct needle stimula
16、tion,Features 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 critically ill patient with thick filament
17、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).,6. Differential Diagnosis,CIPDirect needle stimulation of the muscle Electrical inexcitability in CIMThere is a
18、response in CIP (Fig. 7)Serum CKMuscle biopsy,FIGURE. 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 morphologicDifferentiating 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 corticosteroids,Treatment,Thank you!,
