1. Motility. Voluntary motility system (cortico-spinal tract). Central
motor neuron syndrome, peripheral motor neuron syndrome.
Sphincter disorders. Motor neuron disease. EMG examination:
principles and clinical utility.
ȘEF CATEDRĂ
academician, profesor universitar,
doctor habilitat în științe medicale Stanislav GROPPA
asistent universitar,
doctor în științe medicale Alexandru GASNAȘ
asistent universitar Pavel LEAHU
CATEDRA DE NEUROLOGIE NR. 2
2. Contents
• Motility
• Voluntary movement system (cortico-spinal tract)
• Central motor neuron syndrome (UMN), peripheral motor
neuron syndrome (LMN)
• Sphincter disorders
• Motor neuron disease
• EMG examination: principles and clinical utility
2
3. Overview
• The control of motor function, in which a large part of
the human nervous system is engaged, is achieved
through the integrated action of a wide range of
segmental and suprasegmental motor neurons.
• As originally designed by Hughlings Jackson in 1858, based
on clinical observations, the motor system is organized
hierarchically into three levels, each upper level controlling
the lower.
4. Overview
• The motor and sensory systems, although separate for
practical clinical purposes, are not independent
entities, but are closely integrated. Without sensory
feedback, motor control is inefficient.
• At the upper cortical levels of motor control, motivation,
planning, and other frontal lobe activities that preserve
volitional movement are preceded and modulated by
activity in the parietal sensory cortex.
5. Overview
• Motor activities include not only those that change the
position of a limb or other part of the body (isotonic
contraction), but also those that stabilize posture
(isometric contraction).
• Slow movements are called ramp movements.
• Very fast movements, which are too fast for sensory control,
are called ballistic.
6. Terminology
Paralysis:
- Paresis (partial)
- Plegia (total)
- Monoplegia: paralysis of a limb (usually upper
limb)
- Diplegia: paralysis affecting 2 limbs
- Hemiplegia: total paralysis of the hand, torso
and foot on the same side
- Paraplegia: motor and sensory impairment of
the lower extremities
- Quadriplegia (Tetraplegia): paralysis of all
limbs
7. Central/ upper motor neuron (UMN)
• The central part of the motor system for voluntary movement consists of
the primary motor cortex (area 4) and adjacent cortical areas
(especially the premotor cortex, area 6) and the corticobulbar and
corticospinal tract starting from these cortical areas.
8. Voluntary movement
pathway
• Motor impulses for voluntary movement
are generated in the precentral gyrus of
the frontal lobe (primary motor
cortex, Brodmann area 4) and in
adjacent cortical areas (first motor
neuron).
• They travel through long fiber pathways
(mainly the corticonuclear and
corticospinal tract = pyramidal pathway,
passing through the brainstem and down
to the spinal cord to the anterior horn,
where they connect to second motor
neurons - usually through one or several
interneurons.
9. Voluntary movement
pathway
• The nerve fibers exiting area 4 and the adjacent
cortical areas together form the pyramidal tract,
which is the fastest and most direct link between
the primary motor area and the motor neurons of
the anterior horn.
• In addition, other cortical areas (especially the
premotor cortex, area 6) and the subcortical nuclei
(especially the basal ganglia) participate in the
neuronal control of movement.
• These areas form complex feedback loops with
each other and with the primary motor cortex and
cerebellar cortex; having an influence on the
anterior horn cells through several distinct fiber
pathways in the spinal cord.
• Their function is mainly to modulate movement
and regulate muscle tone.
10. Voluntary movement
pathway
• The impulses generated in the
second motor neuron of the cranial
motor nerve nuclei and the anterior
horn of the spinal cord pass through
the anterior roots, the nerve plexuses
(in the cervical and lumbosacral
regions) and the peripheral nerves on
their way to the skeletal muscles.
• The impulses are transported to the
muscle cells through the synaptic
plates of the neuromuscular junction.
11. Voluntary movement
pathway
• Injuries to the first motor neuron in the brain or
spinal cord usually produce spastic paresis
• Injuries to the second motor neuron in the anterior
horn, anterior root, peripheral nerve, or
neuromuscular synaptic plaque usually produce
flaccid paresis.
• Motor deficiencies rarely occur isolated as a result
of an injury to the nervous system;
• They are usually accompanied by sensory, autonomic,
cognitive and/ or neuropsychological deficits of
different types, depending on the location and nature
of the causal lesion.
12. UMN – Cortical areas
• The primary motor cortex (precentral gyrus) is a band
of cortical tissue located on the opposite side of the central
sulcus from the primary somatosensory cortex (in the
postcentral gyrus) and, like this, extends upward and
passes the superior-medial edge of the hemisphere on its
medial surface.
• The area representing the neck and larynx is at the lower
end of the primary motor cortex; above it, in order, are the
areas representing the face, upper limbs, torso and lower
limbs.
• This is the inverted "motor homunculus", corresponding to
the "somatosensory homunculus" of the postcentral gyrus.
13. UMN – Cortical areas
• Motor neurons are found not only in area 4, but also in adjacent
cortical areas. However, the fibers that mediate fine voluntary
movements come mainly from the precentral gyrus.
• Cortical area 4 - the origin of the characteristic, large pyramidal
neurons (Betz cells), which are in the fifth cell layer of the cortex and
send efferent myelinated axons with a fast conduction forming the
pyramidal tract.
• The pyramidal pathway was once thought to be composed entirely of
Betz cellular axons, but is now known to represent only 3.44% of its
fibers. The largest quota of fibers actually comes from the smaller
pyramidal and spindle cells in Brodmann areas 4 and 6.
• The axons derived from area 4 represent approximately 40% of all the
fibers of the pyramidal tract; the rest come from other frontal areas,
from areas 3, 2 and 1 of the parietal somatosensory cortex
(sensorimotor area) and from other areas of the parietal lobe.
14. Cortico-spinal tract
(Pyramidal)
• The origin in the motor cortex, moves through the cerebral white
matter (corona radiata), the posterior segment of the inner capsule (the
fibers are very close), the central portion of the cerebral peduncle (crus
cerebri), pons, and the base (the anterior portion) of the spinal cord,
where the tract is observed externally as a slight prominence called a
pyramid.
• The medullary pyramids (there is one on both sides) give the name of the
tract. At the lower end of the spinal cord, 80-85% of the pyramidal
fibers cross to the other side in the so-called decussation of the
pyramids.
• Fibers that do not cross here descend the spinal cord into the ipsilateral
anterior bundle like the anterior corticospinal tract; it crosses further
(usually at the level of the segment it supplies) through the anterior
commissure of the spinal cord.
• At the cervical and thoracic level, there are probably also a few fibers that
remain uncrossed and innervate the ipsilateral motor neurons in the
anterior horn, so that the nuchal and truncal muscles receive a bilateral
cortical innervation.
15. Cortico-spinal tract (Pyramidal)
• Most of the fibers of the pyramidal tract intersect in
the decussation of the pyramids, then descend to the
spinal cord in the contralateral lateral bundle as the
lateral corticospinal tract.
• This tract shrinks in cross section as it moves
through the spinal cord, as some of its fibers
terminate in each segment along the way.
• Approximately 90% of all pyramidal tract fibers
terminate in synapses on interneurons, which
then transmit motor impulses to the large α
motor neurons of the anterior horn, as well as to
the smaller γ motor neurons.
16. Cortico-nuclear tract
(cortico-bulbar)
• Some of the fibers of the pyramidal tract branch
from the main mass of the tract as it passes through
the midbrain and then take a dorsal course toward
the nuclei of the motor cranial nerves.
• The fibers that supply these brainstem nuclei are
partly cross-linked and partly non-cross-linked.
• The nuclei that receive the efferents of the
pyramidal tract are those that mediate the
voluntary movements of the cranial muscles
through the cranial nerves V (trigeminal nerve), VII
(facial nerve), IX, X and XI (glossopharyngeal
nerves, vagus and accessories) and XII (hypoglossal
nerve).
17.
18. Cortico-nuclear tract
(cortico-mesencephalic)
• There is also a contingent of fibers traveling
with the corticonuclear tract that originate not
in areas 4 and 6, but rather in area 8, the frontal
orbital area.
• The impulses in these fibers mediate the
conjugated movements of the eyes, which are a
complex motor process.
• Due to its special origin and function, the
pathway coming from the frontal eye fields has a
separate name (cortico-mesencephalic tract),
although most authors consider it a part of the
cortico-nuclear tract.
19. Cortico-nuclear tract
(cortico-mesencephalic)
• The cortico-mesencephalic tract develops in tandem with
the pyramidal tract (only rostral to it, in the posterior arm
of the internal capsule) and then goes dorsally to the
nuclei of cranial nerves that mediate eye movements -
cranial nerves III, IV and VI (oculomotor, trochlear and
abducens).
• Area 8 innervates the eye muscles exclusively
synergistically, rather than individually.
• Stimulation of area 8 induces the deviation of the
conjugate gaze to the opposite side.
• The fibers of the cortico-mesencephalic tract do not
terminate directly on the motor neurons of the cranial
nerve nuclei III, IV and VI; the anatomical situation here is
complicated and incompletely understood.
20. Central/ upper motor neuron syndrome.
Anatomo-physiology.
Origin:
• Layer V of 4 Brodmann area (primary motor
area) located on the ascending frontal gyrus
of the frontal lobe;
• prefrontal areas 6,8;
• parietal areas 3,1,2,5,7;
• secondary motor area;
• additional motor area.
Projection through bunches:
• corticospinal (pyramidal)
• corticonuclear
21. Upper motor neuron syndrome
Etiology:
• vascular lesions are the most common cause
(heart attacks or strokes);
• intracranial expansive processes (brain
tumors, brain metastases, parasitosis, etc.);
• meningoencephalitis;
• brain trauma;
• infantile encephalopathies;
• demyelinating diseases (multiple sclerosis);
22. Upper motor neuron syndrome
Active motility disorder (paresis / plegia):
• predominantly affects voluntary movements
• for the upper limb it predominates on
extensors, supinators, external rotators and
adductors of the arm
• for the lower limb it predominates on the
dorsal flexors of the foot, the flexors of the leg,
the adductors and the external rotators of the
thigh.
• respects the axial muscles
• central type facial paresis
Passive motility disorder (hypertension):
• it can be installed from the beginning in the
conditions of slow installation of the lesions or
after 3 weeks from the sudden onset of the
damage of the central motor neuron;
• is more distally expressed;
• yields continuously, being elastic (the
phenomenon of the "knife blade");
• amplifies to emotions, orthostasis and cold.
Osteotendinous reflex disorders (hyperreflexia).
23. Upper motor neuron syndrome. Symptomatology.
• Pyramidal pathological reflexes (positive);
• Cutaneous reflexes: abolished.
• Clonus: a succession of rapid, rhythmic contractions, triggered by sudden elongation, with
the maintenance of tension in some muscles.
24. Lower motor neuron syndrome
Peripheral/ lower motor neuron
is the common efferent pathway of
the CNS to the muscles.
Etiology:
• Pericarion lesion;
• Anterior root lesion;
• Plexus injury;
• Trunk lesion;
• Injuries to peripheral nerves.
25.
26. Lower motor neuron syndrome. Symptomatology.
1. Active motility disorder
(paresis or plegia);
2. Passive motility disorder
(hypotonia);
3. Osteotendinous reflex
disorder (hyporeflexia).
27. Lower motor neuron syndrome. Symptomatology.
Involuntary motility disorders (fasciculations):
isolated contractions of a group of muscle fibers
without moving the limb segments.
Trophic disorders (muscle atrophies):
appear a few weeks after injury to the peripheral motor
neuron,
they appear earlier by sectioning the nerve than in cases of
compression.
In slowly progressive lesions, muscle atrophy sets in first.
28. UMN vs LMN syndrome
NMC NMP
Lesion (Injury) Superior to the neuron in the anterior horn of
the spinal cord or superior to the nuclei of the
cranial nerves
Motoneuron in the anterior horns of
the MS, motor neuron fiber or
neuro-muscular junction
Tonus Increased (hypertonia / spasticity) ± clonus Reduced (hypotonia / flask)
Muscle weakness All muscle groups of the lower muscle - more
evident in the flexor muscles; In upper m. -
weakness more expressed in extensors
More distal than proximal. Both
groups affected (flexors +
extensors)
Deep tendon reflexes Hyperreflexion ( ) Reduced or absent
Superficial reflexes Absominal skin reflex usually absent Reduced or absent
Plantar reflex (pathological
reflexes)
Positive Babinski sign Absente
Fasciculations Absent They may be present in the anterior
horn lesion of the spinal cord
Muscle atrophy Late, usually due to low (limb) use Usually present
32. - Impossible to walk (wheelchair, stretcher, stretcher)
In some cases we can also examine:
- Climbing and descending stairs (to detect the deficit of the
iliac psoas muscle and the quadriceps muscle)
- Walking on peaks (to detect internal popliteal sciatica deficit)
- Walking on the heel (to detect the deficit of the external popliteal
sciatica) etc.
- Functional gait (hysterical)
Voluntary movement examination
33. Static exam:
1. Hand "in the swan's neck"
(suffering of the radial nerve)
Voluntary movement examination
34. 2. Hand "in the claw"
or "ulnar claw"
(suffering of the ulnar
nerve).
Voluntary movement examination
Static exam:
36. 4. Shoulder "in
rpaulette" (suffering of
the accessory nerve).
Static exam:
Voluntary movement examination
37. 5. Foot in the “var-equina” position
(lesion of the external popliteal sciatic
nerve).
Voluntary movement examination
Static exam:
38. Static examination of
muscle relief:
1. Condition of normal muscle
trophicity (healthy) - muscle
normotrophy.
Voluntary movement examination
39. 2. Muscular hypotrophy (less often -
atrophy) (variants: “hollow” foot
from Friedreich's disease; “rooster”
foot from Charcot-Marie disease,
etc.).
The muscle volume will be
measured with the centimeter band
on symmetrical portions of the
extremities.
Voluntary movement examination
Static examination of
muscle relief: Muscle
atrophy
Friedreich
Ataxia
Charcot-Marie-Tooth
40. 3. Muscle hypertrophy
(physiological - in special
physical occupations;
gastrocnemius
pseudohypertrophy in
progressive muscular
dystrophy Duchenne, Becker;
muscular hypertrophy type
"Hercules" or "Mr. World
Figure" in Thomsen myotonia).
Voluntary movement examination
Static examination of
muscle relief:
41. Fasciculations are spontaneous contractions of denervated muscle fascicles,
which do not lead to displacement of the limb segments.
In a healthy person the fasciculations are missing or benign fasciculations
can be observed (clinical phenomenon without pathological substrate).
Benign fasciculations are most often located in the calf and eyelid muscles,
less often in the arm.
Benign fasciculations are usually caused by exercise as well as psycho-
emotional strain.
Voluntary movement examination
Static examination of
muscle relief:
42. In a healthy person the fasciculations are missing or benign fasciculations can
be observed (clinical phenomenon without pathological substrate).
Benign fasciculations are most often located on the calf and eyelid muscles,
less often on the arm and interdigital muscles. Benign fasciculations are
usually caused by exercise as well as psycho-emotional strain.
Voluntary movement examination
Static examination of
muscle relief:
43. Pathological muscle fasciculations: usually observed spontaneously,
especially on the scapular and pelvic girdle muscles.
They can be highlighted by percussion of the muscle, by rapid friction of
the skin, by electrical excitations. I don't go to sleep.
Voluntary movement examination
Static examination of
muscle relief:
46. It is done by passive movements in all the patient's joints, on all possible axes,
the patient being invited to keep the examined limbs as relaxed as possible.
1. Normal muscle tone (healthy) - muscle normotony.
2. Muscular hypotonia (atony). The hypotonic muscle is softer to the
touch, loses its usual relief due to flaccidity, its tendon is also softer
and loses its relief.
Voluntary movement examination
Muscle tone examination:
47. 3. Muscle hypertension (variant: "knife blade"). Other causes that can
generate difficulties in performing passive movements in the joints must be
eliminated, such as: osteoarthritis, ankylosis, joint stiffness after long
immobilizations, musculotendinous retractions, joint dislocations, exostoses, etc.
Voluntary movement examination
Examination of muscle tone:
48. It is done with the help of a
dynamometer or resisting
the movements that the
patient performs to
indication.
Muscle strength deficit
grading scale:
5 - healthy force (normal);
4, 3, 2, 1 - intermediate
grades;
0 - total motor deficit.
Voluntary movement examination
Muscle strength examination
49. The presence of motor deficits
1. Barré test:
- superior
- inferior
2. Mingazzini test:
- superior
- inferior
Voluntary movement examination
53. 1. In the healthy person, the osteotendinous, osteo-periosteal, cutaneous and mucosal
reflexes are expressed symmetrically; their intensity depends on age, sex, psycho-
emotional state at the time of examination
2. Decreased or abolished reflexes
3. Exaggeration of reflexes
4. !!! Asymmetry of reflexes (red flag)
Voluntary movement examination !!!
61. Abdominal reflexes (skin reflexes):
- Superior (Th6) -Th7-Th8
- Middle Th8-Th9-Th10
- Inferior (Th10) -Th11-Th12
Voluntary movement examination
Cremasterian reflex (cutaneous reflex).
- The reflex center is located in segments L1-L2
63. External anal reflex
- The reflex center is in the segment S2-S3-S4
Voluntary movement examination
The bulbocavernos reflex
- The reflex center is in the S3-S4 segment
64. Patellar or rotulian reflex (osteotendinous reflex)
- The reflex center is located in segments L2-L3-L4
Voluntary movement examination
71. 1. In a healthy adult, pathological reflexes are not present. Physiologically in
infants and preschool children they may be present due to the fact that
myelination of the pyramidal bundle closes only after the age of 2 years.
2. Positive pathological reflexes occur in various diseases of the central
nervous system.
Voluntary movement examination
Pathological reflexes !!!
78. CLONUS - rotulian
- plantar
1. In healthy people - missing
2. It is present in the lesion of the
central nervous system, having
the same clinical significance as
the positive pathological
reflexes.
Voluntary movement examination
Pathological reflexes
83. Sphincter disorders
(bladder)
83
• Both the autonomic and the voluntary nervous system are involved in
the control of bladder function.
• Disorders of bladder function may follow damage to the paracentral lobe,
hypothalamus, descending pathways of the spinal cord, pre- or
postganglionic parasympathetic nerves, or pudendal nerve.
• The detrusor muscle of the bladder is innervated by parasympathetic
neurons located in the intermediolateral column S2-S4
• Onuf's nucleus consists of additional motor neurons located in the nearby
anterior horn at the same levels.
• The axons in Onuf's nucleus innervate the external urethral
sphincter.
• There is a curious preservation of Onuf nucleus neurons in amyotrophic
lateral sclerosis.
• The internal ureteral sphincter from the neck of the bladder receives its
innervation from the intermediolateral column at the level of T12 - L1,
through the sympathetic prevertebral plexus and the hypogastric nerve.
Detrusor
84. 84
• Urination is a spinobulbospinal reflex.
• In response to stretching, the associated impulses are transported to the
sacral spinal cord.
• Projections of the sacral MS to the PAG are retransmitted to the pontine
urination center (Barrington's nucleus) in the dorsomedial pontine roof,
near the locus caeruleus, which sends descending fibers to the preganglionic
parasympathetic motoneurons in the sacral MS that innervate the bladder.
• The pontine urination center is under the control of the centers in the
hemispherical brain (prosencephalon).
• The descending impulses activate the efferent centers of the sacral MS,
causing the contraction of the detrusor muscle and the relaxation of the
internal sphincter.
• In infants, bladder function is purely reflex, but with cortical maturation and
completion of myelination, inhibitory control over this reflex develops, as
well as voluntary regulation of the sacral cord center and lesions affecting
the afferent and efferent connections between the bladder and conus
medullaris. cause severe disorders of bladder function.
Sphincter disorders
(bladder)
85. 85
• The term neurogenic bladder refers to bladder
dysfunction caused by damage to the nervous system.
• Symptoms of bladder dysfunction are often among
the first manifestations of nervous system disease.
• It can be presented by frequency urination, urgency,
precipitated urination, massive incontinence, difficulty
in initiating urination, urinary retention and loss of
sensations.
• A practical classification of neurogenic bladder
dysfunction is based on urodynamic criteria and
includes the following types: uninhibited, reflex,
autonomic, sensory paralysis, and motor paralysis
Sphincter disorders
(bladder)
86. 86
• In the uninhibited neurogenic bladder, there is a
loss of cortical inhibition of reflex emptying, while
bladder tone remains normal. Bladder distension
causes contraction in response to the stretching
reflex. There is frequent urination, urgency and
incontinence that are not associated with dysuria.
Hesitation can precede urgency. The sensation of the
bladder is usually normal. There is no residual urine.
• The reflex neurogenic bladder occurs due to severe
myelopathy or extensive brain damage that causes
disruption of both the autonomic tracts descending to
the bladder and the ascending sensory pathways
above the sacral segments of the cord. The capacity
of the bladder is small and the urination is reflex and
involuntary. Residual urine volume is variable.
Sphincter disorders
(bladder)
87. 87
• An autonomic neurogenic bladder is one
without external innervation. It is caused by
neoplastic, traumatic, inflammatory and other
lesions of the sacral spinal cord, conus
medullaris or cauda equina, motor or sensory
roots S2-S4 or peripheral nerves and congenital
anomalies such as spina bifida
• There is destruction of the parasympathetic
supply. The sensation is absent and there is no
reflex or voluntary control of the bladder;
contractions occur as a result of stimulation of
intrinsic neural plexuses in the bladder wall. The
amount of residual urine is large, but the
capacity of the bladder is not much increased.
Sphincter disorders
(bladder)
88. 88
• A sensory paralytic bladder presents with
lesions involving the posterior roots or
posterior root ganglia of the sacral nerves or
the posterior columns of the spinal cord. The
sensation is absent and there is no desire to
initiate urination. There may be distension,
dribbling, and difficulty in initiating urination
and emptying the bladder. There is a large
amount of residual urine.
• A motor paralytic bladder develops when the
motor innervation of the bladder is interrupted.
The bladder is distinguished and
decompensated, but the sensation is normal.
Residual capacity of urine and bladder varies.
Sphincter disorders
(bladder)
90. ALS
• Amyotrophic lateral sclerosis (ALS; Lou Gehrig's disease)
causes progressive neurological dysfunction primarily in the
spinal cord, but some evidence indicates that neuronal loss
is more extensive and some patients have associated
frontotemporal dementia.
90
91. ALS - Epidemiology
• The incidence of motor neuron disease is 2 to 100,000 per year.
• There is a slight predominance of males (1.5: 1), and the disease is more
common in middle age and the elderly, with maximum onset at about 60
years.
• Approximately 5-10% of patients have a family history, suggestive of
dominant autosomal inheritance, with a younger age of onset in these
individuals.
• Among family patients, a proportion identified gene mutations for the
enzyme superoxide dismutase
91
92. ALS - Pathogenesis
Two mechanisms of degeneration of motor neurons are
currently considered likely to contribute to the pathogenesis
of this disease:
- excitotoxicity - toxins that interact with glutamate receptors,
leading to cellular calcium overload;
- free radicals - damage to motor neurons by a cascade of
reactions initiated by the uptake of electrons by oxygen free
radicals, e.g. superoxide and peroxide.
92
93. ALS - Pathogenesis
These two mechanisms can work together.
Thus, oxygen free radicals are generated in response to an
increase in intracellular calcium, which in turn can be induced
by unidentified excitotoxins.
93
94. ALS - Pathogenesis
• Pathogenesis: ALS involves the alpha motor neurons (inferior motor
neurons) of the anterior horn of the spinal cord, leading to muscle weakness
that provides evidence of denervation, such as fasciculations and atrophy.
• There is also involvement of the lateral corticospinal tract, leading to
weakness, spasticity, hyperreflexia and Babinski signs.
• The term "amyotrophic" refers to the loss of muscle mass from denervation,
and the "lateral" dysfunction of the corticospinal tract.
• ALS does not cause sensory deficits, and eye movements remain unaffected.
94
95. ALS - Symptoms
Central (upper) motor neuron dysfunction
• Spasticity (rigidity)
• Exaggeration of tendon reflexes (pyramidal
syndrome)
• Presence of pathological reflexes (Babinski,
Rossolimo s.a.)
• Loss of dexterity (frequent stumbling blocks, falls
despite maintaining muscle strength)
Peripheral (lower) motor neuron dysfunction
• Decreased muscle strength or increased fatigue
• Muscle fasciculations
• Muscle atrophy
• Breathing disorders
95
Impairment of the central and peripheral motor
neuron
• Decreased muscle strength (classic ALS muscle
weakness is usually due to peripheral motor
neuron dysfunction)
• Muscle cramps
• Speech and swallowing difficulties
• Instability
Affective symptoms
• Laughing or crying involuntarily
• Depression
Cognitive impairment
• Dementia
97. ALS - Diagnosis
• Blood tests are usually normal, except for a possible modest increase
in creatine kinase.
• EMG usually reveals widespread evidence of denervation due to
damage to the anterior horn cells.
• Nerve conduction studies (NCS = ENG) exclude motor neuropathy
disguised as a motor neuron disease with pure NMP characteristics.
• Spinal MRI may be needed to rule out cord or root compression.
97
98. ALS - Diagnosis
• Due to the serious prognostic implications, motor neuron
disease should be diagnosed with certainty only on the
basis of strict clinical criteria, ideally coexisting UMN and
LMN signs in several regions with evidence of progression.
• All other cases are possible or, in the worst case, probable,
therefore all measures to exclude other potentially treatable
conditions should be taken !!!
98
99. ALS - Pharmacological treatment
• Considering the theory of excitotoxicity in the pathogenesis
of motor neuron disease - riluzole, with antiglutamate
activity.
• This drug has been shown to prolong life in motor neuron
disease, but only for a few months in selected patients.
99
100. ALS - Pharmacological treatment
• Most drug treatment is symptomatic:
• Anticholinergics to reduce saliva secretion when swallowed are
difficult (other approaches to this problem include injecting
botulinum toxin into the salivary glands)
• Baclofen, dantrolene, tizanidine, diazepam for spasticity
• Quinine for cramps
• Antidepressants
• Laxatives (with high fluids) for constipation
• Opiates, diazepam - terminal patients
100
101. SLA - Management
Other measures
• Physiotherapy.
• Means of communication for dysarthria.
• Adaptations at home - evaluated by an experienced occupational therapist.
• Tips from speech therapists and dietitians for dysphagia.
• More severe dysphagia may require a gastrostomy to bypass the defective
swallowing mechanism and to allow adequate fluid and food intake.
• Assisted ventilation for respiratory failure may be justified, e.g. for nocturnal
support, when other aspects of motor function are relatively preserved, but
raise ethical issues in patients with advanced disease, where life can be
prolonged, but also suffering.
• Hospital care for terminally ill patients may be required
101
103. Motor unit
• A motor unit is a motor neuron, its axon and, through its
neuromuscular junctions, all the muscle fibers it innervates.
103
104. Fasciculations
• The muscle fibers of the motor units are
grouped together in a bundle (beam) of
the muscle.
• If a single motor unit is triggered,
Examiner may see the contraction of the
muscle fiber bundle as a small curl or
twitch under the skin Pt.
• Such a contraction is a fasciculation.
• Ex can see fasciculations, and Pt can
see and feel them.
104
105. • Fasciculations are contractions of muscle fascicles, detected by
clinical inspection or by characteristic EMG. These indicate a
hyperexcitable state of the MNP cell membrane, which
depolarizes spontaneously, causing contraction of all muscle
fibers of the motor unit.
• Fibrillations are spontaneous contractions of individual
denervated muscle fibers, detected by characteristic EMG waves.
These indicate a state of hyperexcitability of the muscle fibers
after denervation.
105
106. Myokimia
• When motor units unload
abnormally in groups for
extended periods, they cause a
visible, wavy muscle action
similar to the movement of
worms - called Myokimia.
• The muscles go into a more or
less continuous spasm that can
occur focally or segmentally and
can sometimes affect only the
facial muscles or eye muscles.
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107. Neuromyotonia
• Isaacs syndrome (neuromyotonia)
• Autoimmune disorder
• Characterized by continuous muscle
twitching and myokemia, muscle
hypertrophy, weight loss and
hyperhidrosis associated with the
spontaneous action potentials of the
motor unit on EMG.
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108. Cramps
• There are sustained contractions that
last a few seconds to minutes, often
caused by exercise and relieved by
stretching the muscle.
• EMG shows discharges of high
frequency motor units from 200 to
300 pulses / s.
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110. Electromyography (EMG)
• Normally, motor units are discharged only when
stimulated by NMC or other afferents.
• A needle-electrode inserted into a normal muscle
at rest, connected to an amplifier and a monitor
does not display any electrical activity in the
skeletal muscles at rest.
• When the motor units are discharged, the
monitor screen displays numerous electrical
potentials caused by depolarization of muscle
fibers.
• The recording of this electrical activity in the
muscle is called electromyography (Preston and
Shaprio, 2013)
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112. Valerian degeneration and denervation on EMG
• If the neuronal pericarion is damaged, its axon "dies."
• The process of dissolving the damaged axon and its myelin
sheath is called Wallerian degeneration (August Waller,
1816–1870).
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113. Valerian degeneration and denervation on EMG
• After axonal disruption and wallerian degeneration, the
denervated muscle fibers will not contract in response to
volition, afferent stimuli, or direct electrical stimulation of
the peripheral nerve trunk.
• The ex can cause a contraction of the muscle fibers
denervated by direct mechanical percussion.
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114. Lower/ peripheral motor neuron (LMN)
• The surface membrane of a diseased NMP becomes unstable. The
neuron can discharge spontaneous, random impulses, rather than
discharge only in response to appropriate stimuli.
• All muscle fibers connected to the motoneuron axon contract,
resulting in spontaneous fasciculations.
• Some normal individuals who do not have neuronal disease have
benign fasciculations, especially after exercise
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115. Giant polyphase motor units
• They have a larger amplitude and a more complex shape than normal motor units
• Denervated muscle fibers induce the germination of new axonal terminals from a neighboring intact axon.
• When that axon is triggered, it activates not only the initial number of muscle fibers, but also the previously
denervated adjacent muscle fibers. The higher number of muscle fibers employed determines the potential
of the polyphasic giant EMG
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