motor neuron disease for med students

1. MOTOR NEURON
DISEASES
‫הולצמן‬ ‫מיכל‬,‫נוירולוגיה‬ ‫מחלקת‬,‫בי‬"‫מערבי‬ ‫לגליל‬ ‫ח‬‫נהריה‬

2. Upper motor neuron
Characteristic of upper motor neurone lesions:
 no wasting;
 increased tone of clasp-knife type;
 weakness most evident in anti-gravity
muscles;
 increased reflexes and clonus;
 extensor plantar responses.

3. Upper motor neuron
 Lesion situated peripherally in the cerebral
hemisphere produces weakness of part of
the contralateral side of the body
 Lesion of the internal capsule, are much
more likely to produce weakness of the whole
of the contralateral side of the body & visual
loss
 Lesion in the spinal cord in high cervical level
will cause ipsilateral hemiparessis, below
the neck level ipsilateral monoparessis

4. Lower motor neuron
characteristics of lower motor neurone lesions:
 wasting;
 fasciculation
 decreased tone (i.e. flaccidity)
 weakness
 decreased or absent reflexes
 flexor or absent plantar responses
Anterior horn

5. Bulbar weakness(CN 7-12)

6. Amyotrophic
Lateral Sclerosis

7. Amyotrophic Lateral Sclerosis
 Degenerative disorder of upper and lower
motor neurons of the corticospinal tract
 Anterior motor horn degeneration leads to
lower motor neuron signs
 Lateral corticospinal tract degeneration leads
to upper motor neuron signs

8. Amyotrophic Lateral Sclerosis
 The process is remarkably selective, leaving
special senses, and cerebellar, sensory and
autonomic functions intact
 Tends to start either as a problem in the bulbar
muscles, or as a problem in the limbs
 Initially the involvement tends to be either
lower motor neurone or upper motor neurone
in nature
 the coexistence of both, in the absence of
sensory signs, is the hallmark of motor
neurone disease

9. pathogenesis
 Most cases are sporadic, arising in middle age
adults.
 Zinc-copper superoxide dismutase mutation
(SOD1) is present in some familial cases;
leads to free radical injury in neurons
 Prior to their destruction, motor neurons
develop protein-rich inclusions in their cell
bodies and axons containing ubiquitin

10. Clinical presentation
In 75-80% of patients, symptoms begin with limb
involvement.
Initial complaints in patients with lower limb onset are often
as follows:
 Tripping, stumbling, or awkwardness when running
 Foot drop; patients may report a "slapping" gait
Initial complaints with upper limb onset include the
following:
 Reduced finger dexterity, cramping, stiffness, and
weakness or wasting of intrinsic hand muscles
 Wrist drop interfering with work performance
With bulbar onset (20-25%), initial complaints are as
follows:
 Slurred speech, hoarseness, or decreased volume of
speech

11. Clinical presentation
Emotional and special cognitive difficulties in some
ALS patients are as follows:
 Involuntary laughing or crying
 Depression
 Impaired executive function
 Maladaptive social behavior
Features of more-advanced disease are as follows:
 Muscle atrophy becomes more apparent
 Spasticity may compromise gait and manual
dexterity
 Muscle cramps are common

12. Diagnosis

13. Treatment
 Riluzole, decreasing the release of glutamate
and modifies the rate of progression
50 mg orally twice daily,
Symptomatic treatment:
Limb stiffness - antispasticity agents(baclofen,
tizanidine)
Pain – NSAIDs
Cramps - Quinine sulfate,benzodiazepines

14. Prognosis
 Involvement of bulbar and respiratory muscles
accounts for most of the deaths in patients
with motor neurone disease.
 Median survival – 3 years
 15% will live 5 years after diagnosis

15. ‫ניוון‬ ‫במחלת‬ ‫שחולים‬ ‫הישראלים‬ ‫הישרדות‬ ‫כי‬ ‫מצאו‬ ‫בישראל‬ ‫לראשונה‬ ‫שנאספו‬ ‫נתונים‬
‫שרירים‬(ALS)‫בעולם‬ ‫שמדווחת‬ ‫מזו‬ ‫ארבעה‬ ‫עד‬ ‫שניים‬ ‫פי‬ ‫ארוכה‬.‫כי‬ ‫מדווח‬ ‫בספרות‬
‫רק‬10%-5%‫שנים‬ ‫מעשר‬ ‫יותר‬ ‫שורדים‬ ‫מהחולים‬,‫מ־‬ ‫למעלה‬ ‫בעוד‬20%‫בקרב‬
‫יותר‬ ‫שרדו‬ ‫הישראלים‬.

16. Primary lateral sclerosis
 Disease of the voluntary muscle due to UMN
lesion
 Symptoms: spasticity, weakness and stiffness
of legs, drop foot.
 occurs spontaneously after age 50 and
progresses gradually over a number of year

17. Spinal Muscular Atrophy
 autosomal-recessive disorders, characterized by
progressive weakness of the lower motor
neurons.
 Related to defect on SMN1 gene on chromosome
5q
 characterized by loss of anterior horn cells
 Patients usually presenting with muscle weakness
and wasting in the limbs, respiratory, and bulbar
or brainstem muscles
 The most common types are acute infantile (SMA
type I, or Werdnig-Hoffman disease), chronic
infantile (SMA type II), chronic juvenile (SMA type
III or Kugelberg-Welander disease), and adult
onset (SMA type IV) forms.

18. Thank you for listening…