The first symptoms of<unk>  are numbness, tingling, and pain, alone or in combination. This is followed by weakness of the legs and arms that affects both sides equally and worsens over time. The weakness can take half a day to over two weeks to reach maximum severity, and then becomes steady. In one in five people, the weakness continues to progress for as long as four weeks. The muscles of the neck may also be affected, and about half experience involvement of the cranial nerves that supply the head and face; this may lead to weakness of the muscles of the face, swallowing difficulties and sometimes weakness of the eye muscles. In 8%, the weakness affects only the legs (paraplegia or paraparesis). Involvement of the muscles that control the bladder and anus is unusual. In total, about a third of people with<unk>  continue to be able to walk. Once the weakness has stopped progressing, it persists at a stable level ("plateau phase") before improvement occurs. The plateau phase can take between two days and six months, but the most common duration is a week. Pain-related symptoms affect more than half, and include back pain, painful tingling, muscle pain, and pain in the head and neck relating to irritation of the lining of the brain. Many people with<unk>  have experienced the signs and symptoms of an infection in the 3–6 weeks before the onset of the neurological symptoms. This may consist of upper respiratory tract infection (rhinitis, sore throat), or diarrhea. Various patterns of manifestation of<unk> . In children, particularly those younger than six years old, the diagnosis can be difficult and the condition is often initially mistaken (sometimes for up to two weeks) for other causes of pains and difficulty walking, such as viral infections, or bone and joint problems. On neurological examination, characteristic features are the reduced strength of muscles and reduced or absent tendon reflexes (hypo- or areflexia, respectively). However, a small proportion have normal reflexes in affected limbs before developing areflexia, and some may have exaggerated reflexes. In the Miller Fisher variant of<unk>  (see below), a triad of weakness of the eye muscles, abnormalities in coordination, as well as absent reflexes can be found. The level of consciousness is normally unaffected in<unk> , but the Bickerstaff brainstem encephalitis subtype may feature drowsiness, sleepiness, or coma. Respiratory failure A quarter of all people with<unk>  develop weakness of the breathing muscles leading to respiratory failure, the inability to breathe adequately to maintain healthy levels of oxygen, and/or carbon dioxide in the blood. This life-threatening scenario is complicated by other medical problems such as pneumonia, severe infections, blood clots in the lungs, and bleeding in the digestive tract in 60% of those who require artificial ventilation. Autonomic dysfunction The autonomic or involuntary nervous system, which is involved in the control of body functions such as heart rate and blood pressure, is affected in two-thirds of people with<unk> , but the impact is variable. Twenty percent may experience severe blood-pressure fluctuations and irregularities in the heart beat, sometimes to the point that the heart beat stops and requires pacemaker-based treatment. Other associated problems are abnormalities in perspiration and changes in the reactivity of the pupils. Autonomic nervous system involvement can affect even those who do not have severe muscle weakness.
Guillain–Barré syndrome
Myasthenia gravis
Tension myositis syndrome
Botulism
Lambert–Eaton myasthenic syndrome
Acute flaccid myelitis
FACES syndrome
CMV polyradiculomyelopathy