Ultrasonography and Electrophysiology in GBS

Overview

Description of the time course of nerve ultrasonography changes in correlation to nerve conduction studies (NCS) and clinical course.

GBS is an acute- or subacute-onset polyradiculoneuropathy that often follows an upper or lower respiratory illness or gastroenteritis by 10 to 14 days. Approximately 70% of patients can identify a preceding illness, although it is often benign and may be minimized or forgotten by the patient. GBS evolves over days, often beginning with numbness in the lower limbs and weakness in the same distribution. The progression of symptoms, particularly weakness, can be rapid, resulting in quadriplegia within a few days. About 50% of patients develop some degree of facial weakness. Weakness attributed to other cranial nerves includes ocular dysmotility, pupillary changes, and ptosis. Thirty percent of patients with GBS develop respiratory failure from phrenic nerve disease, requiring intubation and ventilation. Autonomic involvement is common in GBS, with the most common manifestations being tachycardia, bradycardia, hypertension and hypotension, gastric hypomotility, and urinary retention. Evidence-based research supports the use of immunotherapy for GBS; proven therapies are IV immunoglobulin (IVIg) and plasma exchange, which have been shown to be equally efficacious in the management of GBS. At present, no biomarkers exist in the blood, urine, or CSF that confirm the diagnosis of GBS. Most patients with GBS will have an elevated CSF protein, but this laboratory finding may not be present until 3 weeks after the onset of the illness. Nerve conduction studies (NCS) play an important role in support GBS diagnosis and subtype classification. In the first few days of the illness, nerve conduction studies may be normal or only show subtle changes of demyelination, such as prolonged or absent F waves and H reflexes, and patchy changes in distal latencies in patients with AIDP. More recently, there has been a rise in the use of peripheral nerve ultrasound (US) in the investigation of peripheral neuropathies. Whilst nerve conduction studies (NCS) are helpful at providing information on the function of nerves, US is able to provide information on nerve morphology. The value of nerve ultrasonography (NUS) in immune-mediated polyneuropathies is well described in the previous studies. In post-GBS patients patchy and slight enlargements have been reported. Whereas in acute stage cervical spinal nerve enlargement and hypertrophy of the vagus are probably the most obvious findings. However, only little is known about the course of nerve morphology from onset until clinical recovery.

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Central Contacts