A motor neuron is a neuron whose cell body is located
in the motor cortex, brainstem or the spinal cord and
whose axon projects to the spinal cord and outside of
the spinal cord to directly or indirectly control effecter
organs, mainly muscles and glands.
Upper motor neuron
Upper motor neuron that starts in the motor cortex of
the brain and terminates within the medulla or within
the spinal cord.
Lower motor neuron;- they are located in either the
anterior grey column, anterior nerve root or the cranial
nerve nuclei of the brainstem and cranial nerves with
Motor neuron disease
MNDs are group of neurodegenerative disorders that
selectively affect motor
neurons, the cells which
control voluntary muscles
of the body.
MND affect both children and adults. While each MND affects
patients differently, they all came with movement relate
symptoms, mainly muscle weakness.
Sporadic degenerative disease involving only motor system
Usual age is 40-60 years
CN are also controlled by upper motor neuron of the
contralateral side- these are known as cortico-bulbar tract
When lesion is present in the CN nucleus it is called as
bulbar palsy (usually 9 10 11 12)(LMN)
When lesion is present in the cortico-bulbar tract (UMN) it
is called as pseudobulbar palsy
Progressive muscular atrophy
(duchenne-aran muscular atrophy)
Progressive muscular atrophy (PMA) is a very rare
subtype of motor neuron disease (MND) that affects
only the lower motor neurons. PMA is thought to
account for around 4% of all MND cases.
As result of lower motor neuron degeneration, the
symptoms of PMA include:
Types of SMA
• Distal spinal
Each individual has 2 SMN genes, SMN1 and SMN2.
More than 95% of patients with SMA have a homozygous
disruption in the SMN1 gene on chromosome 5q, caused by
mutation, deletion, or rearrangement. However, all patients
with spinal muscular atrophy retain at least 1 copy of SMN2,
which generates only 10% of the amount of full-length SMN
protein versus SMN1. This genomic organization provides a
therapeutic pathway to promote SMN2, existing in all
patients, to function like the missing SMN1 gene.
Progressive bulbar palsy
PBP is a disease that attacks the nerves supplying
the bulbar muscles. These disorders are characterized
by the degeneration of motor neurons in the cerebral
cortex, spinal cord, brain stem, and pyramidal tracts.
This specifically involves the glossopharyngeal
nerve (IX), vagus nerve (X), and hypoglossal
Prognosis for PBP patients is poor. progressive
difficulty with talking and swallowing. Reduced gag
reflexes, weak palatal movements, fasciculations, and
weak movement of the facial muscles and tongue.
Progressive Bulbar Palsy
‘’Bulb’’ refers to the
The PBP used to describe
MND affecting bulbar
muscles, causing dysarthria
vagus, hypoglossal nerve.
Progressive difficulty with talking and swallowing.
Reduced gag reflexes, weak palatal movement, of facial
muscles and tongue.
Unable to protrude tongue or manipulate food in their
Difficulty in pronunciation, drooling saliva.
Due to difficulty in swallowing food and saliva, it can be
inhaled into the lungs. This can cause gagging and choking
and increase risk for pneumonia.
Poor prognosis, death occur after 1-3 years of onset of
Spinal and bulbar muscular atrophy (SBMA), popularly
known as Kennedy's disease, is a progressive
debilitating neurodegenerative disorder
resulting in muscle cramps
and progressive weakness
due to degeneration of
motor neurons in the
brainstem and spinal cord.
Monomelic muscular atrophy
Rare benign LMND restricted to one limb, usually an arm or
hand rather than a leg.
Also k/a Hirayama syndrome.
Affects men 10 times more then women.
Starts at 20 years .
Weakness involves he hand and forearm C7-T1 innervated
Condition progress to 1-2 years and then seems to become
arrested in most cases.
Monomelic muscular atrophy
Monomelic amyotrophy (MMA) is characterized by
progressive degeneration and loss of motor neurons,
the nerve cells in the brain and spinal cord that are
responsible for controlling voluntary muscles. It is
characterized by weakness and wasting in a single
limb, usually an arm and hand rather than a foot and
Primary lateral sclerosis
PLS affects the upper motor neurons (also called
corticospinal neurons) in the arms, legs, and face.
It occurs when nerve cells in the motor regions of the
cerebral cortex gradually degenerate, causing
movements to be slow and effortful.
The disorder often affects the legs first, followed by the
body, trunk, arms and hands, and, finally the bulbar
muscles (muscles that control speech, swallowing, and
Primary lateral sclerosis
PLS is similar to ALS, but it affect only UMN.
Causes weakness, stiffness in arms legs, a slowed walk,
poor coordination and balance slow and slurred speech.
Like ALS it usually starts in people 40-60 years old. The
muscle get stiffer and weaker with time. But unlike ALS,
people don’’t die from it.
Symptoms include weakness, muscle stiffness and
spasticity, clumsiness, slowing of movement, and
problems with balance and speech.
PLS is not fatal. There is no cure and the progression
of symptoms varies. Some people may retain the
ability to walk without assistance, but others
eventually require wheelchairs, canes, or other
Pseudobulbar lateral sclerosis
The condition is usually caused by the bilateral
damage to corticobulbar pathways, which are upper
motor neuron pathways that course from the cerebral
cortex to nuclei of cranial nerves in the brain stem.
characterized by the inability to control facial
movements (such as chewing and speaking) and
caused by a variety of neurological disorders. Patients
experience difficulty chewing and swallowing, have
increased reflexes and spasticity in tongue and
the bulbar region, and demonstrate slurred speech
It is a UMND characterised by inability to control facial
movements (chewing, speaking) and caused by a variety
of neurological disorder.
Patients experience difficulty in chewing and swallowing,
have increased reflexes and spasticity in tongue and the
bulbar region and demonstrate slurred speech .
1. Amyotrophic lateral sclerosis
Also known as Lou Gehrig
disease after the famous
baseball player who had this
disease in US.
•ALS is progressive MND that involves both upper and
lower motor neurons. ALS is defined by evidence of both
lower motor neuron disease (weakness, wasting and
•upper motor neuron disease (spasticity, hyperactive
tendon reflex, Hoffmann signs, Babinski or donus) in the
Amyotrophic lateral sclerosis
The jendrassik maneuver is a medical maneuver
wherein the patient clenches the teeth, flexes both sets
of fingers into hook like form. The tendon below the
patient’s knee is then hit with a reflex hammer to elicit
the patellar reflex.
Middle and late life disease.
10% begin <40 years age, 5% begin <30 years .
Men:Females (1-2 times more often than females) females
2.6/100000, male 3.9/100000.
The most common type of MND, amyotrophic lateral
sclerosis (ALS), probably affects up to 30,000 Americans at
any given time, with over 5,600 diagnoses each year,
according to the ALS Association.
A 2012 study Trusted Source found that footballers have a
higher risk of dying from ALS, Alzheimer's disease, and
other neurodegenerative diseases, compared with other
people. Experts think that this could indicate a link with
recurrent head trauma.
Difficult body movements
Difficulty in swallowing
No sensory involvement
Eye movement is not affected
Bowel and bladder functions are normal
Mentation is normal
Normal sexual function
Cognitive functions are normal
Patients are very prone to aspiration pneumonia
Weak cough is a poor prognostic feature
Death after 3-5 years
Terrible depression great suicidal tendency
Riluzole – Action; Anti glutamate action. (Slow down the
progression of disease cannot reverse the disease)
Dose – 100mg resulted in 90% increase in probability of
survival for 2 year when taken for 18 months.
Drugs used for mx of spasticity
The second medication,
edaravonne, was approved in 2017.
Edaravone is a free radical
scavenger believed to prevent
motor neuron degeneration on by
reducing oxidative stress. It is
administered as an intravenous
In a select patient population (≤2 years from first
amyotrophic lateral sclerosis symptom, minimal
respiratory involvement, and minimal disability based
on amyotrophic lateral sclerosis revised functional
rating scale), edaravone was associated with slower
decline over 6 months compared with placebo.
Impaired Physical Mobility related to muscle wasting,
weakness, and spasticity
Impaired Self-Care related to muscle wasting, weakness,
Impaired Communications related to impairment of
muscles of speech
High Risk for Aspiration related to impaired muscles of
Ineffective Breathing Pattern related to impairment of
Altered Nutrition, Less Than Required, related to inability