lower motor disorders

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Amr Hassan, M.D. Associate professor of Neurology - Cairo University

LOWER MOTOR

DISORDERS

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1. The anterior (ventral) horn cell 2. The radicle (root).

3. The peripheral nerve. 4. The neuromuscular junction. 5. The muscle.

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Motor Neurone diseases

Disorders of the AHC Motor Neurone Diseases (MNDs)

Definition:

• A group of purely motor degenerative

disorders that involve selective loss of the

function of upper and/or lower motor

neurons innervating the voluntary

musculature of the limb and bulbar regions.

Motor Neurone Diseases (MNDs)

Classification : • Combined LMN and UMN involovement

Amyotrophic lateral sclerosis

• Pure UMN involovement

Primary lateral sclerosis

Hereditary spastic paraplegia

• Pure LMN involovement =Spinal muscular atrophy (SMA)

Acute infantile SMA (Werdnig-Hoffmann syndrome).

Bulbo-SMA (Kennedy's syndrome).

Chronic childhood SMA (Kugelberg-Welander syndrome).

Distal SMA.

http://www.neuro.wustl.edu/neuromuscular/synmot.html









MND

UMNL

primary

Lateral sclerosis

Hereditary spastic

paraplegia

LMNL

Acute infantile SMA (Werdnig-

Hoffmann syndrome

Bulbo-SMA (Kennedy's syndrome

Chronic childhood

SMA (Kugelberg-Welander

syndrome).

Distal

SMA.

COMBINED








Pure UMNL Pure LMNL

Bulbar (cranial

nerves)

Pseudo bulbar

palsy

True bulbar palsy

Limbs Spastic

quadriplegia

Progressive muscular

atrophy

Pseudo bulbar palsy True bulbar palsy

Bulbar symptoms: Dysphagia,dysarthria,

hoarseness of voice

recurrent choking attacks.

Dysphagia,dysarthria,

hoarseness of voice,

nasal tone of voice,

nasal regurgitation.

Platal and pharyngeal reflex Exaggerated Lost

Emotional lability Commonly present Absent

Jaw reflex Exaggerated Normal


Definition:

• Motor degenerative disorders that involve selective loss of the function of upper and lower motor neurons.

Pathogenesis:

• Oxidative stress theory: Disruption of cell detoxification mechanismsoxidative stress on neurons neuronal degeneration.

• Loss of certain neurotrphic factors: These factors are responsible for maintenance and survival of neurons.


• Lou Gehrig was a Major League Baseball player who played first base for the New York Yankees from 1923-1939. Gehrig set the records for most grand slams in a season and most consecutive games played. Gehrig was stricken with amyotrophic lateral sclerosis, now commonly known as Lou Gehrig's disease.


Clinical picture: ALS has gradual onset and progressive course.

Cranial nerves examination:

• Oculomotor nerves: are usually spared

• Pseudobulbar palsy


Motor system examination: Weakness both U.L.s and L.L.s, usually starts at U.L.

Weakness of neck muscles chin drop.

= Tonic Atrophy

Combined features of UMNL and LMNL: UMNL: +ve Babinski sign, hyperreflexia.

N.B. Sensory system examination: Normal (as purely motor disorder)

LMNL:wasting(D>P), fasiculations (tongue &bulky muscle).


Diagnosis: can be made on clinical bases.

Electrophysiological studies:

• Nerve conduction studies are also required to exclude motor neuropathy & to provide evidence of chronic denervation.

Neuroimaging studies: to exclude conditions which may cause UMN and/or LMN signs that may simulate ALS e.g. focal quadriparesis due to cervical cause.


Treatment: A) Non -Pharmacological:

Speech therapy. d) Physiotherapy.

Nutritional support. e) Occupational therapy.

Respiratory therapy. f) Mental health care.

B) Pharmacological:

1. Symptomatic treatment: e.g. muscle relaxant for treatment of stiffness.

2. Potentially disease modifying drugs:

Glutamate antagonists: Riluzole: 50-200 mg / d.

Antioxidant drugs : e.g. Vitamin E.

Neurotrphic factors: e.g. Nerve growth factor.

Other lines of treatment:e.g. Stem cell therapy, gene therapy.

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II. Disorders of The Spinal Roots (Radiculopathies)

Intervertebral Disc and Its Disorders

• The intervertebral disc = central gelatinous

part, "the nucleus pulposus," surrounded by a

fibrous tissue ring, "the annulus fibrosus" and

covered from above and below by a

cartilaginous plate.


Acute disc prolapse:

• There is sudden rupture of the annulus fibrosis followed by bulging (herniation) of the nucleus pulposus; this compresses the spinal roots.

• It may occur at any age and usually follows trauma, as lifting heavy objects or jumping to the floor from a height.


B) Spondylosis: • Definition:

It is the gradual, progressive degeneration of the intervertebral discs, specially those which are freely mobile as they are more subjected to the process of wear and tear. The freely mobile discs are mainly found in the cervical and lumbar regions.


B) Spondylosis: • Predisposing factors: Old age and excessive mobility of the

spine as in labourers.

• Pathology:

• In spondylosis, there is degeneration of the annulus fibrosus, leading to herniation of the nucleus pulposus with subsequent compression of adjacent structures. As the weakest parts of the annulus fibrosus are the lateral and posterior parts, the herniation will be either lateral, posterior or posterolateral.

Acute disc prolapse Lumbar spondylosis

Age Any age Middle and old age

Cause Traumatic Degenerative

Onset Acute Gradual

X-ray Narrowed intervertebral space. Narrowed intervertebral space sclerosis,

lipping & osteophytes.

Selected Radiculopathies Cauda Equina

Cauda Equina

Causes of cauda equina lesions: • Congenital: Spinabifida.

• Traumatic:

• Fracture or fracture dislocation of

• the lumbar vertebrae.

• Post traumatic disc prolapse.

• Inflammatory: Pott's disease of the

• lumbar vertebrae.

• Neoplastic.

• Degenerative: lumbar spondylosis.

Cauda Equina

Clinical picture of cauda equina lesions:

Motor manifestations:

L.M.N.

Cauda Equina Root Action Muscles

L2 Flexor of the hip Ileopsoas.

L3 Extensor of the knee Quadriceps

L4 Dorsiflexion of the ankle Anterior tibial group

L5 Dorsiflexion of the toes Anterior tibial group & glutei

S1 Plantar flexion of the ankle and toes Calf muscles & glutei

S2 Flexor of the knee Hamstrings

S3, 4, 5 Anal contraction Anal and perianal muscles

Cauda Equina

Sensory manifestations:

• The sensory impairment affects both

superficial and deep sensations. Initially

irritative lesion radicular pain destructive

lesion hyposthesia or anaesthesia in the

dermatome supplied by the affected root.

Cauda Equina Root Sensory

L1 Upper third of the front of the thigh.

L2 Middle third of the front of the thigh

L3 Lower third of the front of the thigh.

L4 Antero-lateral aspect of the thigh, Front of the knee, of the knee , Antero - Medial

aspect of the leg, medial aspect of the dorsum of the foot and the foot and big toe.

L5 Lateral aspect of the thigh and leg, Middle third of the dorsum of the foot and

Middle three toes.

S1 Postero-lateral aspect of the thigh and leg, Lateral third and little toe .

S2 Posterior aspect of the thigh and leg and sole of the foot.

S 3,4, 5 Anal, perianal and gluteal region (saddle-shaped area).

Cauda Equina

Autonomic manifestations:

• Sphincteric manifestations are usually late unless the lesion is bilateral and affects mainly S2,S3,S4 roots (roots of innervation of the bladder). The Sphincteric disturbances are in the form of: sensory atonic bladder,Motor atonic bladder or Autonomic bladder.

• Vasomotor changes and trophic ulcers may occur in the L.L.

Cauda Equina

Investigations: 1) Plain X-ray:

Narrowing of the intervertebral disc spaces.

Sclerosis of the adjacent surfaces of the vertebrae.

Lipping or osteophytic formations due to calcification of the prolapsed parts and ligaments

Straightening of the spines (loss of lordosis).

2) M.R.I

can visualize the intervertebral discs, degree of disc herniation, vertebrae, the facet joints, the nerves, and the ligaments in the spine and can reliably diagnose nerve compression.

Cauda Equina

Treatment:

There is no treatment to reverse the process of spondylosis, because it is a degenerative process.

The treatments of spondylosis target the back pain and neck pain.Available treatments fall into several categories:

General measures:

• Bed rest prolongs the time to recovery. Therefore, it is recommended to continue normal or near normal activities. However, do not do anything that could exacerbate the problem, such as heavy lifting.

• Some people find heat and/or ice to be helpful for back and neck pain caused by spondylosis.

Cauda Equina

Medical: Analgesics &muscle relaxants.

Physiotherapy.

Adjunctive therapies.

Chiropractic spinal manipulation may be helpful to some people, especially within the first month of pain.

Acupuncture.

Injections and Minimally Invasive Procedures for Spondylosis:Steroids (cortisone) can be injected into the epidural space (the space surrounding the spinal cord). This is known as an epidural injection.

http://www.emedicinehealth.com/script/main/art.asp?articlekey=98554

http://www.emedicinehealth.com/script/main/art.asp?articlekey=102586

Cauda Equina

Surgical: Surgery is rarely necessary in patients with acute back pain, unless progressive neurologic problems develop,surgical interference is indicated in cases of:

1. Severe intolerable pain.

2. Bladder disturbances (in cases of cervical spondylosis), denoting severe cord compression.

3. Motor weakness.

4. Marked Sensory deficit.

Conus lesion Epiconus lesion

Anatomically lowermost three segments of the

spinal cord S3,S4,S5

L4,L5,S1,S2

Motor affection No motor disability in L.Ls Weakness or paralysis in L.Ls, in the

muscles supplied by L4S2. revise

table. )

Sensory affection No sensory loss in the lower limbs.

- ↓ sensations in saddle-shaped

area.

↓ sensations from L4 to S2 segment.

Sphincteric

affection

Early urinary incontinence

(autonomic bladder) and faecal

incontinence.

- Impotence.

Precipitancy may occur

B.Sciatica

Definition: It is radicular pain along the distribution of the sciatic nerve (L4,5,S1,2,3) i.e. along the back of the thigh, leg and foot.

The most common causes of sciatica are:

• Acute disc prolapse.

• Lumbar spondylosis.

B.Sciatica Spinal canal at the

lumbosacral regions

Intervertebral

foramina

Pelvis Sciatic nerve

- Acute lumbar disc

prolapse.

- Fracture dislocation.

- Lumbar spondylosis.

- Pott's disease or

tumours.

- Neurofibroma

- Ankylosing

spondylitis.

- Radiculitis.

Compression of

sciatic plexus over

the sacro-iliac joint

by:

- Malignant

tumours of the

bladder,rectum..

- Pelvic abscess.

- Pregnant

retroverted

uterus.

- Neuritis as diabetic,

alcoholic and

rheumatic.

- Pressure on the nerve

by dislocated head of

femur.

- Wrong injection into

the nerve.

B.Sciatica

Clinical picture of sciatica:

• Sensory manifestations: Pain and paraesthesias along the course of the sciatic nerve, aggravated by walking which stretches the nerve and also by coughing, straining or sneezing. Tenderness on direct pressure on the sciatic nerve.

• Motor: Slight L.M.N. weakness in the muscles supplied by the nerve The paravertebral muscles may be spastic; resulting in loss of lumbar lordosis.

• Signs of meningeal irritation: +ve Kernig, Lassegue & Brudzinski signs.

B.Sciatica

• Investigations: M.R.I. lumbosacral spine

• Treatment: Treatment of the cause.

C. Cervical Spondylosis

It may present by one of the 3 following manifestations

depending on the direction of prolapse of the disc.

1. Manifestations of root compression (lateral prolapse):

a) Ventral root compression: There is motor weakness or paralysis in one or both lower limbs of a L.M.N. nature involving the muscles which are supplied by the affected root. The function of each root can be easily tested in the following muscles:


Root Action Muscle

C l,2 Lateral movement of neck Sternomastoid & trapezius

C 3.4 Elevation of shoulder Supra and infraspinatus

C5 Abduction of shoulder Deltoid

C 5,6 Flexion of elbow Biceps & brachioradialis

C 6,7 Extension of elbow Triceps

C 7.8 Extension of wrist Extensors of wrist

C 8,T 1 Flexion of wrist & movement of small ms of

hands

Flexors of wrist


• Posterior root compression:The sensory impairment

affects both superficial and deep sensations. Initially

irritative lesion radicular pain destructive

lesion hyposthesia or anaesthesia in the

dermatome supplied by the affected root.

Root Sensory distribution

C2 Lateral aspect of neck

C3,4 Shoulder down to manubrium anteriorly

C5 Lateral aspect of arm

C6 Lateral aspect of forearm, thenar eminence & thumb

C7 Middle aspect of forearm, middle of palm, middle 3 fingers

C8 Medial aspect of forearm, hypothenar eminence & little finger

T1 Medial aspect of arm


2. Manifestations of cord compression (Posteroir

prolapse):

This results in weakness or paralysis with signs of U.M.N.L.

3. Manifestations of root and cord compression (Postero–lateral prolapse):

Combined features of UMNL and LMNL: In the lower limbs ,UMNL: +ve Babinski sign, hyperreflexia.

In the upper limb ,LMNL:wasting(D>P), fasiculations

(tongue &bulky muscle).

D.Brachial Neuralgia

Definition: It is radicular pain along the distribution of the brachial plexus (C5 —> Tl) i.e. in the shoulder and U.L.

Causes:

• It may be due to:

• Cervical spondylosis and disc prolapse.

• Cervical rib.

• Brachial neuritis: a mononeuritis multiplex of acute onset due to infection or post-vaccine.

• Referred pain from the heart (angina, myocardial infarction), or gallbladder.

D.Brachial Neuralgia

Clinical picture:

• Sensory manifestations: Pain and paraesthesias along the course of the brachial plexus.

• Motor: Slight L.M.N. weakness in the muscles supplied by the the brachial plexus.

Investigations:

• M.R.I. cervical spine and EMG and NC study.

Treatment: Treatment of the cause.

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III. Diorders of the peripheral nerves Peripheral Neuropathy

Definition:

• It is inflammation or degeneration of the peripheral nerves and/or the cranial nerves resulting in impairment of the conductivity of these nerves leading to motor, sensory and autonomic manifestations.

Classification of peripheral nerves

• There are three types of peripheral nerves:

Motor

Sensory

Autonomic.

Classification of peripheral neuropathies

1. Mononeuropathy: affecting a single nerve trunk in one limb.

2. Mononeuropathy multiplex: affecting more than one nerve trunk in one limb.

3. Polyneuropathy: systemic affection of the peripheral nerves of all limbs.

Classification of peripheral neuropathies

Acute , Chronic ,

Subacute,

intermittent

Axonal vs

demyelinating Sensory vs motor

Inherited vs

acquired

Peripheral neuropathy

Peripheral Neuropathy

Causes of Mononeuropathy (DVTI):

• Diabetes mellitus.

• Vascular: polyarteritis nodosa.

• Trauma: wrong injection into a nerve, callus compression.

• Infective: leprosy, herpes zoster.


Causes of polyneuropathy: • Amyloidosis

• Paraneoplastic syndromes: bronchial carcinoma, lymphoma, myeloma

• Collagen vascular disorders: e.g. rheumatoid arthritis, polyarteritis nodosa, scleroderma and systemic lupus erythematosis.

• Drugs and toxins: e.g. I.N.H, cycloserine, sulphonamides, corticoids, phenytoin, vincristine.

• Diabetes mellitus.

• Deficiency disorders: e.g. beri beri, pellagra, S.C.D.

• Endocrinal causes: acromegaly, myxoedema

• Organ Failure: liver and renal failure

• Granulomatous e.g. sarcoidosis.

• Heridofamilial:

• Infection:

– Viral: acute post-infective poiyneuritis, mumps, measles.

– Bacterial: diphtheria, typhus, typhoid, tetanus.

– Mycobacterial: leprosy.

• Immune mediated: Landry-Guillain-Barre syndrome (acute post-infective polyneuropathy).

• Idiopathic.


Clinical picture of polyneuropathy:

A. Motor:

• Weakness or paralysis of L.M.N. nature (wasting, hypotonia, hyporeflexia . . .).

• The weakness and wasting are:

• Bilateral and symmetrical.

• Affecting L.L. > U.L.

• Affecting distal muscles > proximal muscles.

• Affecting extensors > flexors, so weakness in the extensors of the distal group of muscles leads to bilateral foot drop and wrist drop.


Clinical picture of polyneuropathy:

Sensory:

• Irritative lesion: distal pain and paraesthesia in the limbs.

• Destructive lesion:

• Superficial sensory impairment of the stock and glove distribution.

• Deep sensory loss specially distally with absence of deep reflexes sensory ataxia.

Autonomic:

• Vasomotor: coldness and cyanosis of the limbs.

• Cutaneous: loss of hair, brittle nails, trophic ulcers.

Positive Symptoms

Negative Symptoms

Somatic Nerves

Sensory Pain Numbness

Tingling Lack of feeling

Motor Cramps Weakness

Fasciculations Atrophy

Autonomic Nerves

Hyperhydrosis Orthostatic hypotension

Diarrhea Impotence

Anhydrosis

Constipation

Table 4. Positive and Negative Symptoms Associated with Nerve Damage

Diabetic Polyneuropathy

Diabetes mellitus is the most common cause of neuropathy worldwide.

• Length-dependent Diabetic Polyneuropathy

More than 80% of patients with clinical diabetic neuropathy have a distal symmetrical form of the disorder.


Selected polyneuropathies

Diabetic Neuropathy

Pathogenesis

Diabetic microangiopathy of the vasa nervosa ischaemia of the nerves, 2ry to atherosclerosis of the vasa nervosa.


Diabetic Neuropathy

Clinical picture:

Sensory manifestations:

• The polyneuropathy is mainly sensory.

• In early diabetes or in the pre-diabetic stage, the neuropathy is of the mononeuritic type which may affect the sciatic, femoral, lateral popliteal, ulnar or median nerves or Cr. III, VI or VII nerves Then the neuropathy is of the polyneuritic type.


Diabetic Neuropathy Autonomic manifestations: e.g. impotence, sensory, motor or

autonomic bladder, postural hypotension, gastroparesis, ,hyperhydrosis or anhydrosis, trophic skin changes(ulcers, loss of hair, brittle nails) and Charcot's neuropathic joint.

Motor manifestations:weakness may occur late in the disease.

Treatment:

1. Proper management of diabetes: diet, oral hypoglycaemic drugs or insulin.

2. Drugs for treatment of neuropathic pain.


Acute Infective Polyneuritis

Landry-Guillain-Barre Syndrome

Aetiology:

It is due to an allergic or auto-immune reaction secondary to a previous non-specific virus infection.



Landry-Guillain-Barre Syndrome

Clinical Picture:

• Febrile stage: it starts with an influenza-like attack with fever, headache, malaise, pains all over the body with no nervous symptoms.

• Latent stage: the above symptoms disappear and the patient is free for 1-4 weeks.



Landry-Guillain-Barre Syndrome Paralytic stage:

• There is acute severe weakness or paralysis starting in the L.L. and ascending to involve the trunk and respiratory muscles, followed by the U.L. muscles.

• Weakness is proximal more than distal.

• Sensory impairment may occur.

• Early in the disease there is tenderness of the calves.

• The cranial nerves are usually involved specially Cr. VII and X resulting in bilateral facial paralysis and bulbar symptoms.


Chronic Immune Demyelinating Polyneuropathy (CIDP)

Epidemiology: Male > Female: 2:1

Clinical picture: Motor affection > Sensory affection

– Onset: Slowly progressive, relapsing-remitting course

– Motor system:

– Weakness: Proximal > Distal ,Symmetric.

– Tendon reflexes: Reduced or absent.

– Sensory system: • All modalities are affected.

– Cranial nerves: • Ocasional, mild, symmetric weakness of VII, X, XII.

http://neuromuscular.wustl.edu/mother/reflex.html

http://neuromuscular.wustl.edu/nanatomy/vii.htm


Chronic Immune Demyelinating Polyneuropathy (CIDP)

Investigations:

– Electrophysiology: Conduction block and demyelinating neuropathy.

– Nerve biopsy: Onion bulbs in peripheral nerve.

Treatment: Steroids, I.V. immune globulin, plasma exchange and immunosuppressant drugs.

http://neuromuscular.wustl.edu/antibody/pnimdem.html

http://neuromuscular.wustl.edu/pathol/nervedem.htm

Hereditary motor sensory neuropathy (Charcot Marie Tooth)

• Charcot–Marie–Tooth neuropathy is a

genetically and clinically heterogeneous group of inherited disorders of the peripheral nervous system

http://en.wikipedia.org/wiki/Peripheral_nervous_system

http://en.wikipedia.org/wiki/Peripheral_nervous_system


• It has a gradual onset and a very slow, progressive course.

• The wasting and weakness start in the lower limbs in the peronii muscles then the anterior tibial group, then ascend to involve the muscles of the lower 1/3 of the thigh resulting in the inverted champagne - bottle appearance.

• In spite of the marked degree of wasting there is mild disturbance of motor power (i.e. discrepancy between the degree of wasting and the degree of motor weakness).

• Sensations are impaired specially the vibration sense which is markedly diminished.

• Skeletal deformities are usually present e.g., pes cavus, scoliosis.

• It was classified from groups I to VII:

http://en.wikipedia.org/wiki/Scoliosis


Type Other names

HMSN1 Charcot–Marie–Tooth disease type 1

HMSN2 Charcot–Marie–Tooth disease type 2

HMSN3 Dejerine–Sottas disease

HMSN4 Refsum disease

HMSN5 Charcot–Marie–Tooth disease with pyramidal features

HMSN6 Charcot–Marie–Tooth disease with optic atrophy

HMSN7 HMSN + retinitis pigmentosa

http://en.wikipedia.org/wiki/Charcot%E2%80%93Marie%E2%80%93Tooth_disease










http://en.wikipedia.org/wiki/Dejerine%E2%80%93Sottas_disease





http://en.wikipedia.org/wiki/Refsum_disease













http://en.wikipedia.org/wiki/Retinitis_pigmentosa

http://en.wikipedia.org/wiki/Retinitis_pigmentosa

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NMJ Disorders

II. Disorders of The Neuromuscular Junction

Myasthenia Gravis

Definition

An autoimmune disorder that affects acetylcholine receptors interfering with neuromuscular transmission causing easy fatigability of skeletal muscles.

Immunopathogenesis

• Normally thymus gland is the site where T lymphocytes mature.

• Thymic dysfunction abnormal auto-reactive T cells activation of B cells production of autoantibodies directed to the acetylcholine receptors on the postsynaptic side of the neuromuscular junction in skeletal muscles impairment of the neuromuscular transmission.

Clinical features

• Diurnal variation

• Descending order ↓

• Easy fatigability

• More common in Females

Clinical features

Cranial nerve affection

• Ocular muscles are affected first in 40% of patients and eventually in 85%.

• Ptosis and diplopia are common presentations.

• Bilateral LMN facial weakness.

• True bulbar palsy dysarthria, dysphagia, nasal tone of voice and nasal regurgitation of fluids.

Clinical features

Respiratory muscle weakness:

may cause respiratory failure in severe cases

Motor system:

The disease gradually progress to involve more skeletal muscles, usually in a descending order limb weakness proximal > distal.

Sensory system:

Sensations are normal (MG is a neuro MUSCULAR disorder).

Diagnosis

Clinical testing :

• Neostigmine test: mix 0.6mg of atropine sulfate with 1.5 -2.5mg of neostigmine in a 3 cc syringe , change is usually apparent within 15 min. and is most obvious 30 min following injection.

• Fatigability tests: repetition of a given action, such as maintaining upward deviation of the eyes for testing for the eyelidsappearance of ptosis

Diagnosis

Acetylcholine receptors antibodies: 85-90% of generalized cases and 50% of ocular cases.

Electromyography:

• Neuromuscular transmission studies may show a decremental response in the amplitude of the muscle action potential with repetitive nerve stimulation at 3 Hz. A decrement of more than 10% when comparing the fifth to the first response is positive.

• Single-fiber electromyography.

CT chest with contrast: to exclude thymoma.

Treatment

• Anticholinesterases

• Corticosteroids.

• Plasmapheresis.

• IVIG.

• Thymectomy.

Prognosis

• If untreated may end in respiratory failure and death.

• Spontaneous remission may occur, usually after several years.

The myasthenic crisis

• Myasthenic crisis occurs when weakness from acquired myasthenia gravis becomes severe enough to necessitate intubation for ventilatory support or airway protection.

Triggers:

• Infections e.g. upper respiratory tract infection.

• Physical stress (such as trauma or a surgical procedure, including thymectomy).

• Changes in medications e.g. recent initiation or tapering of corticosteroid dosage.

• In 30% to 40% of crises, no obvious trigger can be identified.

Management:

• ICU admission and supportive care.

• Removing triggers.

• Plasma exchange.

The myasthenic crisis

Triggers:

• Infections e.g. upper respiratory tract infection.

• Physical stress (such as trauma or a surgical procedure, including thymectomy).

• Changes in medications e.g. recent initiation or tapering of corticosteroid dosage.

• In 30% to 40% of crises, no obvious trigger can be identified.

Management:

• ICU admission and supportive care.

• Removing triggers.

• Plasma exchange.

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1. The anterior (ventral) horn cell . 2. The peripheral nerve. 3. The neuromuscular junction. 4. The muscle.

Muscle diseases

V. Disorders of The Muscles Mypopathy

• Causes of myopathy

• Primary Myopathies:

– Muscular dystrophies (MD):

X-linked AD AR

Duchenne

(DMD)

Becker

(BMD)

Limb girdle MD;

Facioscapulohum

eral (FSH)

Myotonia

dystrophica

Oculophayngeal

MD.

Distal MD.


• Congenital myopathies: Myotubular (Centronuclear) Myopathy; Nemaline Myopathy; Central Core Disease.

• Metabolic/Enzyme deficiency:Phosphorylase deficiency (MCardle), Acid maltase deficiency (Pompe), Phosphofructokinase deficiency (Tarui), Debrancher enzyme deficiency (Cori Forbes) and mitochondrial myopathy.


Secondary Myopathies – Infectious: e.g. trichinosis; cysticercosis; toxoplasmosis;

Lyme disease; Staph aureus pyomyositis; human immunodeficiency virus (HIV); coxsackie A and B viruses; influenza.

– Toxic/Metabolic: e.g. alcohol, several medicines (corticosteroids; AZT; statins; colchicine; amiodarone; cocaine).

– Endocrinal: Corticosteroids (Addison or Cushing), hyper or hypothyroidism, hyperparathyroidism.

– Inflammatory: Polymyositis, dermatomyositis, inclusion body myositis.

Duchenne Muscular Dystrophy (DMD)

Definition:

• Is a recessive X-linked form of muscular dystrophy, affecting around 1 in 3,600 boys, which results in muscle degeneration and weakness.

http://en.wikipedia.org/wiki/Sex_linkage



http://en.wikipedia.org/wiki/Muscular_dystrophy



• Congenital myopathies: Myotubular (Centronuclear) Myopathy; Nemaline Myopathy; Central Core Disease.

• Metabolic/Enzyme deficiency:Phosphorylase deficiency (MCardle), Acid maltase deficiency (Pompe), Phosphofructokinase deficiency (Tarui), Debrancher enzyme deficiency (Cori Forbes) and mitochondrial myopathy.


Definition:

• Is a recessive X-linked form of muscular dystrophy, affecting around 1 in 3,600 boys, which results in muscle degeneration and weakness.







• Genetics: • The disorder is caused by a mutation in the dystrophin gene,

located on the human X chromosome, which codes for the protein dystrophin, an important structural component within muscle tissue.

• Since women have two X chromosomes, if one X chromosome has the non-working gene, the second X chromosome will have a working copy of the gene to compensate. Because of this ability to compensate, women rarely develop symptoms. Males have only one X chromosome, so one copy of the mutated gene will cause DMD.

http://en.wikipedia.org/wiki/Dystrophin

http://en.wikipedia.org/wiki/Gene

http://en.wikipedia.org/wiki/X_chromosome

http://en.wikipedia.org/wiki/Protein


Clinical picture:

• Usually appear in male children < 5 years and may be visible in early infancy.

• Progressive proximal muscle weakness of the legs and pelvis associated with a loss of muscle mass is observed first inability to climb the stairs then weakness spreads to the arms, neck, and other areas, low endurance, and difficulties in standing unaided or inability to ascend staircases.


Clinical picture: • The weakness is of L.M.N. nature i.e. it is associated with

wasting, hypotonia, hyporeflexia. The weakness and wasting are bilateral, symmetrical and proximal more than distal i.e., the shoulder and arm are more affected than the forearm and hand and the hip and thigh are more affected than the leg and foot.

• Pseudohypertrophy develops as the condition progresses, muscle tissue experiences wasting and is eventually replaced by fat and fibrotic tissue (fibrosis). Pseudo hypertrophy affect mainly the gluteus maximus, quadriceps and calf muscles in the L.L., and the deltoid, supra and infra spinatus muscles in the U.L.

http://en.wiktionary.org/wiki/pseudohypertrophy

http://en.wikipedia.org/wiki/Fibrosis


Clinical picture: The weakness and wasting of the shoulder, pelvic girdle and trunk muscles

results in:

• a) Winging of the scapulae due to weakness of the serratus anterior and trapezius.

• b) Pot-belly abdomen due to weakness of the abdominal muscles.

• c) Exaggerated lumbar lordosis due to weakness of the extensor muscles of the trunk in an attempt from the patient, to prevent himself from falling forwards by the effect of gravity.

• d) Waddling gait due to weakness of the gluteus medius & minimus (abductors of the hip).

• e) Characteristic manner in getting up from the floor (climbing test or Gower's sign) due to weakness of the gluteus maximus.


Clinical picture:

• There is selectivity of the involved muscles e.g., there is atrophy of the sternal head of the pectoralis major with preservation of its clavicular head.

• Later on there are fibrosis and contractures of the affected muscles resulting in skeletal deformities e.g. pes cavus and talipes equinus.

• No mentality changes, sensory changes or sphincteric disturbances.

Gower sign


Complications:

• Deformities (particularly kyphosis).

• Permanent, progressive disability manifested as decreased mobility or decreased ability to care for self.

• Cardiomyopathy.

• Pneumonia or other respiratory infections.

• Respiratory failure.

http://en.wikipedia.org/wiki/Kyphosis

http://en.wikipedia.org/wiki/Cardiomyopathy

http://en.wikipedia.org/wiki/Pneumonia

http://en.wikipedia.org/wiki/Respiratory_failure


Investigations: • Creatine phospho kinase (CPK-MM) levels in the bloodstream

are extremely high.

• An electromyography (EMG): small MUP, polyphasesity, early recruitement which denote muscle disease.

• DNA testing : DNA testing confirms the diagnosis in most cases.

• A muscle biopsy confirms the absence of dystrophin, although improvements in genetic testing often make this unnecessary.

• E.C.G. changes, histological changes in the heart due to associated cardiomyopathy.

• Prenatal tests: via Chorion villus sampling (CVS) ,Amniocentesis or Fetal blood sampling.

http://en.wikipedia.org/wiki/Creatine_kinase

http://en.wikipedia.org/wiki/Electromyography

http://en.wikipedia.org/wiki/Biopsy

http://en.wikipedia.org/wiki/Dystrophin


Treatment:

• There is no current cure for DMD.

• Treatment is generally aimed at controlling the onset of symptoms to maximize the quality of life e.g. corticosteroids such as prednisolone and deflazacort.

• Physical therapy is helpful to maintain muscle strength, flexibility, and function. Orthopedic appliances (such as braces and wheelchairs) may improve mobility and the ability for self-care.

• Appropriate respiratory support.

http://en.wikipedia.org/wiki/Corticosteroids

http://en.wikipedia.org/wiki/Prednisolone

http://en.wikipedia.org/wiki/Deflazacort


Prognosis:

• Duchenne muscular dystrophy is a progressive disease which eventually affects all voluntary muscles and involves the heart and breathing muscles in later stages. The life expectancy is currently estimated to be around 25.

Becker muscular dystrophy (BMD)

Definition:

• Is a recessive X-linked form of muscular dystrophy affecting around 3 to 6 in 100,000 male births which results in muscle degeneration and weakness.

Genetics:

• Becker muscular dystrophy is related to Duchenne muscular dystrophy in that both result from a mutation in the dystrophin gene, but in Duchenne muscular dystrophy no functional dystrophin is produced making DMD much more severe than BMD.





http://en.wikipedia.org/wiki/Duchenne_muscular_dystrophy

http://en.wikipedia.org/wiki/Duchenne_muscular_dystrophy

Becker muscular dystrophy (BMD)

Duchenne MD Becker MD

Age of onset 1st decade 2nd and 3rd decades

Dystrophin Absent Deficient

Severity of the

condition

Severe Less severe

Course Progressive Slowly progressive

Skeletal deformities Present Absent

E.C.G. changes Commonly present Absent

Facioscapulohumeral muscular dystrophy

• AD

• Initially affects the skeletal muscles of the face (facio), scapula (scapulo) and upper arms (humeral).

• it is widely stated to be the third most common genetic disease of skeletal muscle.

• Symptoms may develop in early childhood and are usually noticeable in the teenage years.

http://en.wikipedia.org/wiki/Skeletal_muscles

http://en.wikipedia.org/wiki/Scapula

http://en.wikipedia.org/wiki/Humeral

http://en.wikipedia.org/wiki/Genetic_disease

http://en.wikipedia.org/wiki/Muscle


• A progressive skeletal muscle weakness usually develops in other areas of the body as well; often the weakness is asymmetrical.

• Life expectancy is normal, but up to 15% of affected individuals become severely disabled and eventually must use a wheel chair.

http://en.wikipedia.org/wiki/Life_expectancy

http://en.wikipedia.org/wiki/Wheel_chair

Limb-girdle muscular dystrophy

• This is a heterogeneous group of conditions that usually appear in adolescence or adult life with proximal limb weakness. The weakness usually progresses slowly, but it may arrest spontaneously.

• There are at least 15 different mutations that contribute to LGMD

• Some of them are AR,others are AD.

Myotonic Dystrophy

Definition of myotonia: Delayed relaxation of the skeletal muscles after voluntary, mechanical or electrical stimulation.

– Voluntary: when the patient voluntarily clenches his fist, he is unable to open his hand, except after sometime.

– Mechanical:on tapping the thenar eminence, adduction of the thumb occurs with difficulty & delay in abduction.

– Electrical: 2-3 milliamperes are sufficient to produce contraction of the muscle due to hyperexcitability.

The myotonic phenomenon: Improves by: repetition of movement, warmth, calcium, quinine, procamamide and worsened by: cold, potassium and prostigmine.

Myotonic Dystrophy

• Myotonic dystrophy is an AD condition, usually begins in childhood or young adult life.

• Myotonic dystrophy, as opposed to most forms of myopathy, is characterized by distal weakness, affecting the muscles of the hands before more proximal musculature.

• In addition, facial (muscles of mastication) and neck musculature are involved early.

• Numerous non-neurologic problems are found: frontal balding, testicular atrophy, diabetes, cardiac arrhythmias, and others. It progresses slowly.

Myositis Polymyositis

• Definition: It is an acquired autoimmune disease of the skeletal muscle.

• Clinical Picture:

• Age: usually above 30 years, unless there is an associated collagen disorder.

Myositis Polymyositis

• Onset: acute or subacute with general symptoms of fatigue followed by:

• Pain and tenderness of the muscles (60% of cases).

• Weakness affecting: – The proximal muscles of U.L. and L.L.

– The posterior neck muscles (forward lolling of the head).

– The pharyngeal and laryngeal muscles (bulbar symptoms).

• No involvement of the ocular muscles.

• The deep reflexes are intact.

Dermatomyositis In this disease the clinical picture of polymyositis is

associated with cutaneous manifestations as Gottron papules on dorsum of hand and heliotropic rash on upper eyelid.

Investigations:

1. labs: ↑ E.S.R, ↑↑C.P.K. in serum.

2. E.M.G. shows a myopathic pattern with fibrillation potentials.

Treatment:

1. Steroids.

2. Immunosuppressive drugs.

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lower motor disorders

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