The late effects of Polio Information for Health Care Providers
The characteristic lesions in paralytic polio occur in the grey matter of the brain and spinal cord, hence the term "polio", which originates from a Greek word meaning "grey". The symptoms are of varied type and severity.
Most cases develop only mild symptoms, which are vague, non-specific and indistinguishable from other systemic viral infections. The diagnosis of polio infection on a clinical basis at this stage is difficult.
Approximately 1% of all polio infections are thought to progress to a more severe but non-paralytic form. Meningeal irritation causes headaches, photophobia and neck and back stiffness. Coma may occur.
About 0.1% of all polio infections are said to progress to paralysis. Usually only the anterior horn cells of the spinal cord are affected, resulting in asymmetrical partial or complete weakness of some or all of the muscles supplied by these spinal nerves, including muscles of respiration. Usually, the sensory functions are intact. The autonomic system may be affected. Urinary retention and constipation are common in the acute stage, but later on sphincter function recovers. Ocular muscles are almost always spared.
Brain stem involvement (bulbar polio) occurs in between 5% and 35% of all paralytic cases and results in paralysis of muscles which are supplied by the cranial nerves. This has an effect on breathing and swallowing. Speech may also be disturbed.
Full or partial recovery often occurs spontaneously during the first months to years. This has been attributed mainly to re-innervation of muscle fibres due to "sprouting" from neighbouring intact lower motor neurones, resulting in fewer but larger motor units.
Residual complications often occur, including:
© Copyright The Lincolnshire Post-Polio Network 1997 - 2010.
This document comprises an index, foreword, introduction and seventeen other sections or subdocuments. Permission for printing copies is granted only on the basis that ALL sections are printed in their entirety and kept together as a single document.
Document preparation: Chris
Think-tank, Cornwall, United Kingdom.
Created: 7th July 1997
Last modification: 20th January 2010.
Last information content change: 6th June 2000