Guillain-Barre
also Weakness

• Peripheral neuropathy
• Often follows resp or GI illness (flu, campylobacter)
• Ascending weakness, areflexia, hyperesthesias, autonomic instability
• CSF shows high protein w/out pleocytosis
• EMG shows abnormal nerve conduction velocity
• Treatment is supportive, IVIG, steroids, plasmapheresis
• Miller Fisher variant has cranial nerve involvement

The lower extremity weakness with loss of deep tendon reflexes described for the child in the vignette suggests a lower motor neuron (ie, peripheral nerve) process, although an upper motor neuron (ie, spinal lesion) process should be given brief consideration. Acute spinal cord processes, such as trauma or hemorrhage, can present transiently with absent reflexes during a state of "spinal shock" before the patient develops hyperreflexia. However, in this instance, the child's facial diplegia is further indication of a lower motor neuron process. The combination of facial diplegia plus distal weakness with absent reflexes strongly suggests the diagnosis of Guillain-Barré syndrome.

Guillain-Barré syndrome is an acute postinfectious demyelinating polyneuropathy that is characterized by ascending paralysis progressing over days. Bulbar involvement occurs in fewer than 50% of patients. Pain may occur at the back due to demyelination. The sensory or autonomic nervous system may be involved. Lumbar puncture and examination of the cerebrospinal fluid is essential to the diagnosis. Spinal fluid reveals a normal glucose concentration with no red blood cells or pleocytosis (<10 white blood cells/mm³). Cerebrospinal fluid protein levels are elevated in 50% of patients during the first week of illness and in many more patients following the first week.

Nerve conduction velocities (NCVs) with electromyography (EMG) also can aid in the diagnosis. NCVs augment examination of the peripheral nerves by evaluating the speed, amplitude, and distribution of electrical impulses; concurrent EMG assesses muscle electrical activity. In Guillain-Barré syndrome, nerve conduction is greatly slowed because of demyelination. The child may have absent F-wave responses, which measure conduction in the proximal motor nerve and root, where demyelination is greatest. EMG initially shows evidence of a reduction in recruitment of motor activity. Later, in severe cases, there is evidence of acute denervation to the muscle.

Magnetic resonance imaging is the technique of choice for assessing spinal cord processes, such as trauma or tumor. Electroencephalography assesses cerebral activity, particularly seizures or encephalopathy. Evoked potentials, such as brainstem auditory evoked responses (BAERs) or somatosensory evoked potentials (SSEPs), are neurophysiologic techniques used to assess central nervous system function at the brainstem or spine, respectively. BAERs are useful for assessing auditory function in a patient who does not cooperate with pure tone audiometry or when otoacoustic emissions cannot be obtained. SSEPs best assess the dorsal columns of the spinal cord in central demyelinating disorders such as multiple sclerosis. SSEPs would not reveal cord dysfunction in Guillain-Barré syndrome.    

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