Early Prediction of Respiratory and Autonomic Complications of GBS Using Neuromuscular Ultrasound

Overview

Neuromuscular US will be a good and non invasive predictor for respiratory and autonomic dysfunctions in GBS through evaluation of diaphragmatic thickness, phrenic and vagus nerve cross sectional area.

Patients presented in the ER with clinical manifestations and examination suggesting GBS are admitted to neurology department. Confirmation of the diagnosis of GBS is done by fulfilling the clinical diagnostic criteria, CSF examination is done searching for cytoalbuminous dissociation ,serum electrolytes, toxicological screening ,virology to exclude mimics of GBS. Patients will undergo electrophysiological study (motor NCS of both median ulnar ,tibial ,and peroneal nerves ). Distal motor latency (dmL), nerve conduction velocity (CV) and compound muscle action potential (CMAP)amplitude measurements were undertaken as well as measurements of the mean F-M-latencies of both median ,ulnar and tibial nerves (F-wave latency-dmL). Similarly, sensory nerve conduction study is applied on both median and ulnar nerves ,(dml is assessed. According to the electophysiological study results, patients will be grouped into: * AIDP: If two or more nerves showed demyelinating features (distal latency prolongation, slow nerve conduction velocity, conduction block, or prolonged F wave latency) on motor nerve conduction study. * AMAN: Normal sensory conduction studies and unrecordable or reduced compound muscle action potential on motor nerve conduction study. There should not be more than one demyelinating feature in any nerve. * AMSAN: If both motor and sensory nerve conduction studies revealed features of axonal neuropathy such as reduced or absent CMAP and SNAP, marginal slowing or normal conduction velocity and absence of conduction block. * Inexcitable: Absent CMAP in all motor nerves (or present in only one nerve with CMAP \<10%of lower limit of normal). * Equivocal: GBS patients not fulfilling the above neurophysiologic criteria. Then patients will be assessed clinically using the Medical Research Council (MRC) grading for power and Hughes functional grading scale scores. Muscle groups (right and left) assessed in the measurement of the MRC sums core are: * Abduction of the arm * Flexion of the forearm * Extension of the wrist * Flexion of the leg * Extension of the knee * Dorsal flexion of the foot 0 = No visible contraction 1. = Visible contraction without movement of the limb 2. = Movement of the limb but not against gravity 3. = Movement against gravity over (almost) the full range 4. = Movement against gravity and resistance 5. = Normal The MRC-sums core ranges from 0 (paralytic) to 60 (normal strength). (Kleyweg RP et al.,1988) Guillain-Barré syndrome disability scale 0 A healthy state 1. Minor symptoms and capable of running 2. Able to walk 10 m or more without assistance but unable to run 3. Able to walk 10 m across an open space with help 4. Bedridden or chair bound 5. Requiring assisted ventilation for at least part of the day 6. Dead Basal and every day arterial blood gases unless new respiratory event occurs. Basal pulmonary function test is done. Clinical assessment for autonomic dysfunction: In addition to reported or clinically evaluated symptoms (sweating problems, orthostatic dysregulation, sexual dysfunction). ECG is done day after day and blood pressure measurements five times daily for at least the first seven days of acute hospitalization. Ultrasonography is done on diaphragm, phrenic nerve and vagus nerve. As regard diaphragmatic ultrasound: the index test (ultrasound imaging of the diaphragm) is used. A high-resolution portable ultrasound machine is used, with a 7- to 13-MHz linear array transducer. Patients will be examined in the supine position. The diaphragm was identified as a 3-layered structure lying deep to the intercostals muscles and subcutaneous tissue. 3 images captured at end-expiration and 3 images captured after the patient is asked to inhale as deeply as possible. The transducer is positioned in a sagittal oblique plane, spanning 2 ribs, at approximately the anterior axillary line, overlying one of the most caudal intercostal spaces. Measurements of diaphragm thickness are made using electronic calipers, and the 3 images for each position are then averaged to give a thickness at resting end-expiration (TMIN) and at maximal inspiration (TMAX), from which a diaphragm thickening ratio is derived: TMAX/TMIN. Normal diaphragm thickness is defined as ≥0.14 cm and the normal diaphragm thickening ratio is defined as ≥1.2. As regard phrenic nerve US: Under the guidance of a high resolution ultrasound with the patient's head towards the left, the ultrasound probe (frequency, 7-13MHz) was placed on the right side of the neck. The axial scanning of the neck along the surface of the anterior scalene muscle, showed that the phrenic nerve rounded the anterior scalene muscle from the outside to the inside, and coursed through the trench between the common carotid artery and anterior scalene muscle. As regard vagus us: All participants were examined with HRUS by a(7-12) MHz transducer. Each VN was visualized in the axial plane at the level of the thyroid gland, and three images were recorded at each side. To assess the VN-CSA its contour within the hyperechoic epineural rim was outlined.. The median of the three VN-CSA measurements was used for statistical analyses. Patients then undergo plasmapharesis 50 mL/kg, on 5 separate occasions over 1-2 weeks. Patients after that are evaluated again (4 weeks from the onset of the condition)ie at the end of the acute stage of Guillan Barre syndrome by MRC and Hughes clinical scores and clinical evaluation of autonomic and respiratory dysfunctions will be also assessed . Ultrasound will be done on diaphragm, phrenic nerve and vagus nerve again.

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