Neurological Disorders: Polio

Polio is a neurological disorder caused by a virus, and manifests with flaccid paralysis of skeletal muscles usually resulting in life long disability, and rarely death during the acute stage. A Neurologist is frequently involved in the care of these patients.

The virus has three subtypes, type 1, 2 and 3. Type 1 is the most common and this virus affects only human beings.

This virus generally enters the body through the oral route after ingesting the virus through contaminated water or food arterial with feces of another infected person. It generally proliferates in the oro-pharynx and gastrointestinal (GI). Majority of these people who acquire the virus do not suffer any problems at all. Some will develop symptoms of gastroenteritis including diarrhea etc. Only a small minority (approximately about 1 to 3%) of those who harbor the virus in their gastrointestinal tract will go on to develop the neurological infection.

And the good news again is that those who develop neurological involvement; most of them will develop a condition called as a viral meningitis (type of aseptic meningitis) and this is a self limiting illness. Only small minorities of people are unfortunate and will go on to develop what we call ‘paralytic attack’ and it is of three types;

• Spinal type
• Bulbar type
• Bulbo-spinal type

The virus infects the motor neurons of the spinal cord and brain stem (mainly medulla oblongata part) and induces paralysis of the muscles supplied by these neurons, and the resulting clinical manifestations are enumerated below.

The non-neurological type;

• No symptoms at all
• Gastrointestinal type: fever, sore throat, cough, diarrhea etc

The neurological type;

• Aseptic meningitis (headache, fever, neck stiffness, malaise etc)
• Spinal (asymmetric flaccid paralysis of limbs)
• Bulbar (difficulty with swallowing, breathing, speech difficulties etc)
• Bulbo-spinal (respiratory paralysis, difficulty with swallowing, flaccid limb paralysis etc)

There is more and more recognition of this above condition, and this occurs several years (usually few decades) after the prior poliomyelitis attack. Patients will begin experiencing new onset progressive weakness usually in the same affected limb, however generally with the previously unaffected muscles.

The exact cause of this syndrome is not clear however it is suspected to be due to over-burdening and fatigue of the surviving nerve fibers that are supplying the muscles.

The following neurology tests may be performed to establish the diagnosis;

• CSF (cerebrospinal fluid analysis)
• EMG/NCS (electromyography and nerve conduction study)
• MRI of brain and/or spine (not required always, also may not always help)
• Blood, stool culture for virus
• Blood, CSF for viral antibody titer etc.

Unfortunately there is no cure for poliomyelitis or post-polio-syndrome. Treatment is supportive & symptomatic. Physical therapy, occupational therapies are the mainstay of treatment. Acute severe bulbar poliomyelitis patients require breathing assistance. Orthopedic surgeries, assistive devices like braces, wheel chairs etc may be necessary.