Guillain-Barré syndrome

Guillain-Barré syndrome

1. Guillain-Barré syndrome

2. CONTENTS Overview Etiology Epidemiology Clinical Manifestations Variant forms Diagnosis Treatment References

3. INTRODUCTION Guillain-Barré syndrome is a rare neurological disorder in which the immune system mistakenly attacks part of the peripheral nervous system GBS can range from a very mild case with brief weakness to nearly devastating paralysis

4. ETIOLOGY About two-thirds of GBS patients experience symptoms of an upper respiratory or gastrointestinal tract infection up to 6 weeks prior to onset of GBS. Associated pathogens Campylobacter jejuni (most common disease associated with GBS) Cytomegalovirus (CMV) HIV Influenza Zika virus Epstein-Barr virus SARS-CoV-2 Mycoplasma pneumoniae Vaccination There have been reports of small increases in incidence after administration of certain vaccines. .

5. EPIDEMIOLOGY GBS occurs worldwide with an annual incidence of 0.34 to 1.34 cases per 100,000 persons aged 18 years or less. While all age groups are affected, the incidence is lower in children than in adults. The incidence increases by approximately 20 percent with every 10-year increase in age beyond the first decade of life. GBS occurs rarely in children younger than two years of age but can occur even in infants. There is a case report of congenital GBS in the neonate of an affected mother Males are affected approximately 1.5 times more often than females in all age groups.

6. The classic presentation of GBS begins with paresthesia in the toes and fingertips followed by lower extremity symmetric or modestly asymmetric weakness that may ascend over hours to days to involve the arms and, in severe cases, the muscles of respiration. The typical clinical features of GBS are progressive, mostly symmetric or modestly asymmetric muscle weakness and absent or depressed deep tendon reflexes The predominant symptoms of GBS at presentation in children are pain and gait difficulty. In preschool-aged children, the most common symptoms are refusal to walk and pain in the legs Cranial neuropathy most commonly affects the facial nerves, causing bilateral facial weakness. CLINICAL MANIFESTATIONS

7. Variant forms of guillain-barré syndrome Historically, GBS was considered a single disorder. It is now known to be a heterogeneous syndrome with several variant forms. Acute inflammatory demyelinating polyradiculopathy (AIDP) is the most common type. Each type of GBS has distinguishing clinical, pathophysiologic, and pathologic features. The classic presentation of ascending paralysis is most common, but a number of atypical variants present with local or regional involvement of particular muscle groups or nerves Several have prominent cranial nerve involvement, including Miller Fisher syndrome (MFS), Bickerstaff brainstem encephalitis, polyneuritis cranialis , and pharyngeal-cervical-brachial weakness.

8. VARIANT FORM CHARACTERISTICS Acute inflammatory demyelinating polyneuropathy Prototype of GBS and is the most common form Acute axonal neuropathies More severe course, involvement of motor or motor and sensory nerves, and an electrophysiologic pattern suggesting axonal damage Acute motor axonal neuropathy Pure motor form of GBS and is associated with a preceding  Campylobacter jejuni  infection. Acute motor-sensory axonal neuropathy  Resembles the motor axonal variant but has more sensory symptoms. The course tends to be prolonged and severe GQ1b syndromes Eye movement abnormalities and ataxia rather than limb weakness and numbness. Miller Fisher syndrome characterized by external ophthalmoplegia, ataxia, and muscle weakness with areflexia. Incomplete forms include acute ophthalmoplegia without ataxia and acute ataxic neuropathy without ophthalmoplegia

9. Physical examination findings Physical examination typically reveals symmetric weakness with diminished or absent reflexes and gait abnormalities. Sensory symptoms are usually "positive" ( eg , pain or paresthesia, reflecting nerve irritability) rather than "negative" ( eg , loss of sensation). Clinical course The clinical course of GBS in children is shorter than in adults and recovery is usually more complete. In patients who did not require mechanical ventilation, the median time to recovery of independent walking was 43 to 52 days in children compared with 85 days in adults

10. DIAGNOSIS The initial diagnosis of GBS is based upon the clinical presentation. The weakness can vary from mild difficulty with walking to nearly complete paralysis of all extremity, facial, respiratory, and bulbar muscles. However, some GBS variants present with local or regional involvement of particular muscle groups or nerves, and several have prominent cranial nerve involvement; the variable initial presentations can hinder early diagnosis. In patients with GBS, lumbar puncture often reveals an elevated CSF protein with a normal CSF white blood cell count. This finding, known as albuminocytologic dissociation, is present in 50 to 66 percent of patients with GBS in the first week after the onset of symptoms and ≥75 percent of patients in the third week . The elevated protein may be due to increased permeability of the blood-nerve barrier at the level of the proximal nerve roots. A normal CSF protein is found in one-third to one-half of patients when tested earlier than one week after symptom onset

11. Electrodiagnostic studies Electrodiagnostic studies are the most specific and sensitive tests for diagnosis of GBS and establish the underlying pathophysiology as either demyelinating or axonal. Electrodiagnostic studies are uncomfortable and can be technically challenging in small children In the demyelinating forms of GBS, electrodiagnostic studies demonstrating abnormalities including motor conduction block, slowing of motor and sensory nerve conduction, temporal dispersion, and prolonged distal latencies. In the axonal forms of GBS, nerve conduction studies showing decreased amplitude of motor responses, with normal conduction velocities

12. Magnetic resonance imaging Spinal MRI with administration of gadolinium frequently shows enhancement of the spinal nerve roots and cauda equina during the first weeks after the onset of GBS in children. In some cases, nerve root enhancement may be delayed and observed only on a repeat MRI. Nevertheless, spinal nerve root enhancement is a nonspecific finding that can be seen in a variety of disorders. Thus, the diagnosis of GBS cannot be made by MRI alone. Antibodies Immune reactions directed against epitopes in Schwann cell surface membrane or myelin can cause the acute demyelinating form of GBS, while immune reactions against epitopes contained in the axonal membrane cause the acute axonal forms of GBS. C ommercially available testing for serum IgG antibodies to GQ1b is useful for the diagnosis of Miller Fisher syndrome, having a sensitivity of 85 to 90 percent.

13. Progressing weakness Worsening respiratory status or need for mechanical ventilation Significant bulbar weakness Inability to walk unaided Indications for treatment 

14. During the initial phase of GBS, all patients require close monitoring of motor, autonomic ( ie , BP, HR, and sphincter function), and respiratory function. Serial PFT should be every four hours at the bedside and closely monitored and observed for fatigue and other clinical signs of impending respiratory muscle failure. Patients should be electively intubated if clinical evaluation or pulmonary function tests suggest impending respiratory failure. Mortality is often due to complications such as nosocomial infection, acute respiratory arrest, deep venous thrombosis with pulmonary embolism, and pneumothorax.  TREATMENT Nutritional needs should be addressed early in the disease course. Orogastric tube feeding, gastrostomy, or parenteral nutrition is often necessary The patient's position should be changed frequently for comfort and to avoid skin breakdown. Intermittent-pressure leg boots are used in the intensive care setting to prevent deep vein thrombosis Physical therapy, occupational therapy, and social services should be involved early. 

15. Ventilatory status   Autonomic dysfunction is a well-recognized feature of GBS and is a significant source of mortality. Consequently, close monitoring of blood pressure, fluid status, and cardiac rhythm are essential to the management of these patients. Care must also be taken when vasoactive or sedative drugs are used, because GBS-related dysautonomia may exaggerate the hypotensive responses to these drugs. Autonomic status Approximately 10 to 20 percent of children with GBS require mechanical ventilation for respiratory failure. The need for tracheal intubation should be anticipated so that it can be performed as an elective procedure Children with a vital capacity approximately one-half the normal value for age or ≤20 mL/kg of body weight generally progress to require ventilatory support. Sedation and neuromuscular blockade should be avoided where possible in ventilated patients because they obscure the course of the illness.

16. Plasma exchange Plasma exchange is recommended for those patients who have rapidly progressing weakness, worsening respiratory status, are unable to walk unaided, require mechanical ventilation, or have significant bulbar weakness. As a result of the cost, risk, and discomfort to the patient, plasma exchange generally is not used in very young children, for ambulatory patients with mild disease, or for patients whose symptoms have stabilized. The mechanism is thought to be removal of antibodies directed against nerves from the circulation. Intravenous immune globulin Randomized trials in children suggest that IVIG shortens the time to recovery compared with supportive care alone and it is thought to involve suppression of inflammatory and immune-mediated processes. The total dose of IVIG in children is 2 g/kg, given as 1 g/kg for 2 days or 400 mg/kg for 5 days. IVIG is preferred to plasma exchange in children because of the relative safety and ease of administration IMMUNOTHERAPIES

17. REFERENCES Guillain-Barré syndrome in children: Epidemiology, clinical features, and diagnosis - Uptodate Free. (n.d.). https://pro.uptodatefree.ir/show/6235 Guillain-Barré syndrome in children: Treatment and prognosis - Uptodate Free. (n.d.). https://pro.uptodatefree.ir/show/6204 Guillain-Barré Syndrome. (n.d.). National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/health-information/disorders/guillain-barre-syndrome Guillain-Barré syndrome - Knowledge @ AMBOSS. (n.d.). https://www.amboss.com/us/knowledge/guillain-barre-syndrome/