Motor neuron disease What are motor neuron diseases? Who is at risk? What are the causes motor neuron diseases? How are they classified? What are the symptoms of motor neuron diseases? How are motor neuron diseases diagnosed? How are motor neuron diseases treated? What is the prognosis? What research is being done?

Pure motor : No sensory, no sphincter change , no mentality change and NO ocular defect duration is no too long in adult onset?

WHAT IS MOTOR NEURONS? The cells that control essential voluntary muscle activity such as speaking, walking, breathing, and swallowing.  Normally, messages from nerve cells in the brain (called upper motor neurons) transmitted to nerve cells in the brainstem and spinal cord (called lower motor neurons) via 2 main tracts called corticobulbar and corticospinal respectively and from them to particular muscles. 

The motor neuron diseases (MNDs) are a group of progressive neurological disorders that destroy motor neurons, MNDs may be inherited or acquired. MNDs occur in adults ,symptoms may appear after age 40 and it is of unknown etiology.  The diseases are more common in men than in women.  In children, we called it spinal m. atrophy= SMA I,II,& III. particularly it is inherited or familial forms of the disease, symptoms can be present at birth or appear before the child learns to walk. Only LMN features

Adult type (after age of 40 years) The causes of sporadic, or non-inherited, MNDs are not known, but environmental, toxic, viral, or genetic factors may be implicated.  Sporadic cases may be triggered by exposure to radiation therapy, lightening strike or other electrical injury, cancers, or prolonged exposure to toxic drugs or environmental toxins.  Scientists are investigating whether the body's autoimmune reaction to viruses such as the human immunodeficiency virus can trigger MNDs. Inherited type? There is a familial form of ALS in adults, which often results from mutation of the superoxide dismutase gene, or SOD1, located on chromosome 21.  A rare juvenile-onset form of ALS is genetic. In children ? AR , AD

How are they classified? depend on sites of involvement amyotrophic lateral sclerosis, which affects both upper and lower motor neurons.  Progressive bulbar palsy affects the lower motor neurons of the brainstem, causing slurred speech and difficulty chewing and swallowing.  Patients with these disorders almost always have abnormal signs in the arms and legs.  Pseudobulbar palsy –upper motor n. affection that give rise to corticobulbar tracts results in c/f of SBP Primary lateral sclerosis PLS is a disease of the upper motor neurons . progressive muscular atrophy PMA affects only lower motor neurons in the spinal cord.

Amyotrophic lateral sclerosis (ALS). classical motor neuron disease, it is a progressive, ultimately fatal disorder that eventually disrupts signals to all voluntary muscles.  Although the disease does not usually impair a person's mind or personality, ALS most commonly strikes people between 40 and 60 years of age, but younger and older people also can develop the disease.  Men are affected more often than women.  Most cases of ALS occur sporadically, and family members of those individuals are not considered to be at increased risk for developing the disease.  Both upper and lower motor neurons are affected.  Approximately 75 percent of patients with classic ALS will also develop weakness and wasting of the bulbar muscles (muscles that control speech, swallowing, and chewing).  Symptoms are usually noticed first in the arms and hands, legs, or swallowing muscles.  Muscle weakness and atrophy occur disproportionately on both sides of the body.  Other symptoms include spasticity, exaggerated reflexes, muscle cramps, fasciculations, and increased problems with swallowing and forming words.  Speech can become slurred or nasal.  When muscles of the diaphragm and chest wall fail to function properly, patients lose the ability to breath without mechanical support. Our colleague???????

There is a familial form of ALS in adults, which often results from mutation of the superoxide dismutase gene, or SOD1, located on chromosome 21.  A rare juvenile-onset form of ALS is genetic.  Most ALS patients die from respiratory failure, usually within 3 to 5 years from the onset of symptoms.  However, about 10 percent of ALS patients survive for 10 or more years. Progressive bulbar palsy , also called progressive bulbar atrophy, involves the bulb-shaped brainstem - the region that controls lower motor neurons needed for swallowing, speaking, chewing, and other functions.  Symptoms include pharyngeal muscle weakness, weak jaw and facial muscles, progressive loss of speech, and tongue muscle atrophy With Fasciculation.  Limb weakness with both lower and upper motor neuron signs is almost always evident but less prominent. 

Pseudobulbar palsy , which shares many symptoms of progressive bulbar palsy, is characterized by upper motor neuron degeneration and progressive loss of the ability to speak, chew, and swallow.  Progressive weakness in facial muscles leads to an expressionless face.  Patients may develop a gravelly voice and an increased gag reflex.  The tongue may become immobile and unable to protrude from the mouth.  Patients may also experience emotional lability. Primary lateral sclerosis (PLS) affects only upper motor neurons and is nearly twice as common in men as in women.  Onset generally occurs after age 50.  The cause of PLS is unknown.  It occurs when specific nerve cells in the cerebral cortex (the thin layer of cells covering the brain which is responsible for most higher level mental functions) that control voluntary movement gradually degenerate, causing the muscles under their control to weaken. 

Progressive muscular atrophy is marked by slow but progressive degeneration of only the lower motor neurons.  It largely affects men, with onset earlier than in other MNDs.  Weakness is typically seen first in the hands and then spreads into the lower body, where it can be severe.  Other symptoms may include muscle wasting, clumsy hand movements, fasciculations, and muscle cramps.  The trunk muscles and respiration may become affected.  Exposure to cold can worsen symptoms.  The disease develops into ALS in many patient

How is motor neuron diseases diagnosed? There are no specific tests to diagnose MNDs.  Symptoms may vary among individuals and, in the early stages of the disease, may be similar to those of other diseases, making diagnosis difficult.  Patients should first have a physical exam followed by a thorough neurological exam.  No sensory changes , no ocular abnormality, no sphincter disturbance , no mentality changes Tests to rule out other diseases or to measure muscle involvement may include the following:

Electromyography (EMG) &nerve conduction velocity study ----------------De-innervations Features . NCS Nearly Normal, EMG ----fasicu. and de-innervations pattern Magnetic resonance imaging (MRI) . Laboratory screening tests of blood, urine for heavy metals poisoning. Transcranial magnetic stimulation was first developed as a diagnostic tool to study areas of the brain related to motor activity.  It is now also being used as a treatment for certain disorders.  This noninvasive procedure creates a magnetic pulse inside the brain that stimulates motor activity in a certain area of the body.  Electrodes taped to different areas of the body pick up and record the electrical activity in the muscles.  Read outs of this data may help in diagnosing MNDs and in monitoring disease progression. magnetic resonance spectroscopy MRS : is being used to evaluate function of the upper motor neurons

How are motor neuron diseases treated? There is no cure or standard treatment for the MNDs.  Symptomatic and supportive treatment can help patients be more comfortable while maintaining their quality of life. The drug riluzole (Rilutek®), the only prescribed drug approved by the U.S. Food and Drug Administration to treat ALS, prolongs life by 2-3 months but does not relieve symptoms.  The drug reduces the body's natural production of the neurotransmitter glutamate, which carries signals to the motor neurons.  Scientists believe that too much glutamate can harm motor neurons and inhibit nerve signaling.

PROGNOSIS Prognosis varies depending on the type of MND and the age of onset. generally speaking is bad (4-5 years). Some MNDs, such as PLS, are not fatal and progress slowly.  Patients with SMA( MND of children) may appear to be stable for long periods, but improvement should not be expected.  Some MNDs, such as ALS and some forms of SMA, are fatal . Research options fall largely into three categories: drugs( gabapentin , ceftrioxone, celecoxib=celebrex, Coenzyme Q 10) , growth factors , and stem cells.