1
Q
CNS
A
Brain and spinal cord
2
Q
What dies a typical peripheral nerve consist of?
A
- Numerous nerve fibres
3
Q
What does the PNS include?
A
- Spinal nerve roots
- Plexi
- Named peripheral nerves
- Tiny nerve endings
- NMJ and muscle
4
Q
What is Amyotrophic Lateral Sclerosis (ALS) also known as?
A
Lou Gehrig’s disease.
5
Q
What type of disorder is ALS?
A
A progressive neurodegenerative disorder affecting motor neurons.
6
Q
Which neurons are affected in ALS?
A
Motor neurons in the brain and spinal cord.
7
Q
What are the main clinical outcomes of ALS progression?
A
Muscle weakness, atrophy, and eventual paralysis.
8
Q
At what age does ALS most commonly occur?
A
Middle to late adulthood, most frequently in the fifties.
9
Q
Which gender is more commonly affected by ALS?
A
Which gender is more commonly affected by ALS?
10
Q
Which three anatomical locations of motor neurons are affected in ALS?
A
Anterior horn cells (LMNs) of the spinal cord
Motor nuclei of the brain stem (esp. hypoglossal nuclei)
UMNs of the cerebral cortex
11
Q
What does the death of lower motor neurons (LMNs) cause in ALS?
A
Denervation, muscle shrinkage, and muscle fiber atrophy (amyotrophy).
12
Q
What does “lateral sclerosis” in ALS refer to?
A
Loss of nerve fibers in the lateral columns of the spinal cord white matter with fibrillary gliosis.
13
Q
Which two types of neurons degenerate in ALS?
A
Anterior horn cells (LMNs) and upper motor neurons (UMNs).
14
Q
What are the signs and symptoms of ALS?
A
- Mix of UMN and LMN signs
- Spasticity
- Weakness
- Multifocal muscle atrophy
- Fasciculations
- No sensory loss!
15
Q
Is there a cure for ALS?
A
No
16
Q
How to manage ALS?
A
- Manage their symptoms: weakness and muscle spasm, dysphagia, communication difficulty
- Antiglutamate drug
17
Q
What is the term for sensory or motor dysfunction caused by pathology of a nerve root?
A
Radiculopathy.
18
Q
What is the most common form of radiculopathy?
A
Monoradiculopathy.
19
Q
Which regions of the spine are most commonly affected by radiculopathy?
A
Cervical and lumbosacral regions.
20
Q
Which type of radiculopathy is more common: lumbosacral or cervical?
A
Lumbosacral radiculopathies (2–3 times more common than cervical).
21
Q
Common Causes of radiculopathy
A
- Disc herniation
- Bone spurs
- Spinal stenosis
- Degenerative disc disease
22
Q
General signs and symptoms of radiculopathy
A
- Burning, tingling pain that radiates or shoots down a limb
- Muscle weakness
- Reduced reflex for that root level
- Chronic radiculopathy can result in atrophy and fasciculations
- Pin-prick test is more sensitive
23
Q
Cervical radiculopathy signs
A
- Neck pain that radiates to the shoulder arm or hand along with numbness tingling or weakness in specific areas
24
Q
Lumbar radiculopathy signs/symptoms
A
- Often presents as lower back pain that radiate down the leg (sciatica)
- May also experience numbness, tingling, or muscle weakness in the lower extremity
- Straight leg raising or crossed straight leg raising
- Involvement of multiple nerve roots below L1 can result in a cauda equina
25
T1 radiculopathy signs/symptoms
Can interrupt the sympathetic pathway to the cervical sympathetic ganglia resulting in horners syndrome
26
What are the common management of radiculopathy?
- Most patients with radiculopathy caused by disc herniation recover within a few months without surgery
- MRI if severe
- Surgery
27
What are the surgical approaches to radiculopathy
Laminectomy = removal of the lammina over affected levels
Foraminotomy = widen the lateral recess
Discectomy = remove herniated disc material
28
What is plexopathy?
A PNS syndrome in one limb not explained by a single spinal root or a single named peripheral nerve.
29
What are the two main types of plexopathy?
Brachial plexopathy (shoulder, arm, hand)
Lumbosacral plexopathy (lower back, hip, leg, foot)
30
Which regions of the body are affected in brachial plexopathy?
Shoulder, arm, and hand.
31
Which regions of the body are affected in lumbosacral plexopathy?
Lower back, hip, leg, and foot.
32
What are common causes of plexopathy?
Trauma/stretch, compression by tumor or hematoma, radiation, and diabetes.
33
Which diagnostic test confirms plexopathy?
Electromyography (EMG).
34
When is imaging suggested in suspected plexopathy?
If a compressive lesion is suspected.
35
What are the general signs of brachial plexopathy?
- Muscle weakness and wasting
- Usually normal reflexes
- Loss of sensation
- Normal coordination
36
What is the most common cause of upper brachial plexopathy?
Excessive pulling or stretching of an infants head and shoulders during vaginal birth
37
Signs of upper brachial plexopathy
- Weakness in the shoulder and upper arm muscles, such as the deltoid, biceps and brachialis
- Inability to lift the arm or flex elbow
- Sensory loss may also occur in the lateral aspect of the arm and hand
38
Signs of lower brachial plexopathy
- Weakness and atrophy in the intrinsic muscles of the hand and forearm, resulting in clwa hand
39
Causes of lumbosacral plexopathy
- Pelvic fractures
- Tumors
- Diabetes
- Radiation therapy
- Compression from structures like the psoas muscle or a hematoma
40
In lumbar plexopathy, which regions are most affected by pain and sensory loss?
The anterolateral and medial thigh.
41
Which muscle groups are weak in lumbar plexopathy?
Quadriceps, hip flexors, and hip adductors.
42
In sacral plexopathy, which regions are most affected by sensory loss and weakness?
The posterior thigh, leg, and foot.
43
What is mononeuropathy?
Is a type of peripheral neuropathy that affects a single nerve, causing loss of sensation movement or other functions associated with that nerve
44
Mononeuropathy signs
Weakness, numbness, pain confined to distribution of the nerve
45
Common causes of mononeuropathy
- Entrapment
- Trauma
- Prolonged limb immobility
46
What are some examples of mononeuropathy?
- Ulnar mononeuropathy at the elbow
- Median mononeuropathy at the wrist
47
Mononeuropathy Multiplex
Several nerves such as the ulnar, median and radial become affected simultaneously
48
What causes Mononeuropathy Multiplex
- Diabetes mellitus
- Leprosy
- Vasculitis
- Malignancy
- HIV
49
What is Polyneuropathy?
Refers to a condition where multiple peripheral nerves throughout the body are affected
50
What are the characteristics of polyneuropathy?
- Distal symmetric polyneuropathy
- Affects longest nerves
- Length dependent process
- Symmetrical loss of temperature/vibration/proprioception
- Usually chronic
51
What causes of the axonal neuropathies?
Insults that directly injure the axon = distal portion of axon degenerate = secondary myelin loss
52
What are the hallmarks
A decrease in the density of axons correlates with a decrease in the signal strength or amplitude of nerve impulses in electrophysiologic studies
53
What cells or structures are damaged in demyelinating neuropathies?
Schwann cells or myelin.
54
In demyelinating neuropathies, are axons typically spared or destroyed?
They are relatively spared.
55
What is the hallmark electrophysiological finding in demyelinating neuropathies?
Abnormally slow nerve conduction velocities with preserved amplitude.
56
What term describes discontinuous myelin loss along individual internodes of an axon?
Segmental demyelination.
57
What are the key morphological features of demyelinating neuropathies?
Normal axon density with segmental demyelination and repair.
58
In peripheral polyneuropathy, how do symptoms typically progress in the body?
They ascend from the legs to the fingertips.
59
What are the main motor signs of peripheral polyneuropathy?
Distal weakness (feet, fingers/grip) and muscle atrophy.
60
What are the earliest sensory symptoms of peripheral polyneuropathy?
Numbness, paresthesia, and pain in the feet.
61
What gait abnormality can severe sensory loss in polyneuropathy cause?
Steppage gait.
62
What balance-related problems can occur due to severe sensory loss in polyneuropathy?
Sensory ataxia, imbalance, and falls.
63
Why are the feet especially vulnerable in peripheral polyneuropathy?
They are prone to injuries, ulcers, and deformation.
64
What autonomic dysfunctions may occur in peripheral polyneuropathy?
Bladder dysfunction and erectile dysfunction.
65
Common Causes of Peripheral
polyneuropathy
1.Diabetic Peripheral
Neuropathy
2.Guillain-Barré (GB) Syndrome
3.Chronic Inflammatory
Demyelinating Polyneuropathy
(CIDP)
66
. Diabetic Peripheral Neuropathy
* Diabetes is the most common cause of peripheral neuropathy
*Usually developing with long-standing disease
67
What is the most common form of diabetic peripheral neuropathy?
Distal symmetric sensorimotor polyneuropathy.
68
In distal symmetric sensorimotor polyneuropathy, which axons are more severely affected?
Sensory axons.
69
What is the dominant clinical presentation of distal symmetric sensorimotor polyneuropathy?
Numbness.
70
How does lumbosacral radiculopathy present in diabetic peripheral neuropathy?
With asymmetric pain that can progress to lower extremity weakness and muscle atrophy.
71
What functions are commonly affected in diabetic autonomic neuropathy?
Bowel, bladder, cardiac, and sexual function.
72
What is the most common life-threatening disease of the peripheral nervous system?
Guillain-Barré Syndrome (GBS).
73
GBS is a variant of which broader condition?
Acute Inflammatory Demyelinating Polyneuropathy (AIDP).
74
What typically precedes Guillain-Barré Syndrome?
Viral infection or vaccination.
75
How quickly does Guillain-Barré Syndrome usually progress?
Acutely over about 2 weeks.
76
Which axons are primarily affected in GBS?
Motor axons (demyelination).
77
What is the hallmark clinical presentation of GBS?
Ascending weakness starting in the legs, with early loss of reflexes.
78
What is the most dangerous complication of GBS that can cause death within days?
Respiratory muscle failure.
79
Besides weakness and sensory changes, what systemic issue can occur in GBS?
Autonomic instability, including arrhythmia.
80
What is the most common chronic acquired inflammatory peripheral neuropathy?
Chronic Inflammatory Demyelinating Polyneuropathy (CIDP).
81
How is CIDP clinically characterized?
Symmetrical mixed sensorimotor polyneuropathy persisting for 2 months or more.
82
What is the underlying mechanism of CIDP?
It is immune mediated.
83
What are the typical clinical courses of CIDP?
Chronic, relapsing-remitting, or progressive.
84
CIDP has increased frequency in patients with which types of disorders?
Other immune disorders such as systemic lupus erythematosus (SLE) and HIV infection.
85
What pathological changes are seen in the peripheral nerves of CIDP patients?
Segments of demyelination and remyelination.
86
What results from Schwann cell proliferation and repeated regeneration in CIDP?
Concentric arrangement of multiple Schwann cells around individual axons.
87
Which type of symptoms predominate in CIDP?
Motor symptoms.
88
Is CIDP typically symmetric or asymmetric in its presentation?
Symmetric, involving both arms and legs.
89
In CIDP, which muscles are affected: proximal, distal, or both?
Both proximal and distal muscles.
90
What happens to deep tendon reflexes in CIDP?
They are reduced or absent.
91
What characteristic finding is seen in the cerebrospinal fluid (CSF) of CIDP patients?
Elevated protein without increased cell count (albuminocytologic dissociation).
92
What does nerve conduction testing show in CIDP?
Evidence of a primary demyelinating neuropathy.
93
Investigations for PNS disorders
- Blood tests: gluscose and B12
- Electromyopgraphy helps localise and characterise lesions of PNS
- Imaging for some focal lesions
- CSF analysis
- Nerve biopsy
94
What are the treatments for polyneuropathy
- Managing the underlying condition
- Pain management
- Immunotherapy
95
What structures make up a motor unit?
One lower motor neuron, its axon, neuromuscular junctions, and the skeletal muscle fibers it innervates.
96
What is the neuromuscular junction (NMJ)?
The interface of motor nerve axons and skeletal muscle that controls muscle contraction.
97
The NMJ is formed between which two types of membranes?
The presynaptic membrane (motor axon terminal) and the postsynaptic membrane (muscle fiber).
98
Are neuromuscular junction disorders typically motor, sensory, or mixed?
They are pure motor syndromes.
99
Which neurotransmitter acts at the neuromuscular junction?
Acetylcholine (ACh).
100
What are the common disorders of NMJ
- Myasthenia gravis
- Lambert eaton syndome
- Infections with exotoxin producing bacteria
101
What is the most common disorder of the peripheral neuromuscular junction?
Myasthenia Gravis (MG).
102
What is the incidence of Myasthenia Gravis?
Approximately 2 in 100,000 persons.
103
Which gender is more commonly affected by Myasthenia Gravis, and in what ratio?
Women, with a 3:2 ratio compared to men.
104
What is the peak incidence age for MG in men and women?
Men: 40–70 years; Women: 20–40 years.
105
What type of disorder is Myasthenia Gravis?
An immune-mediated disorder.
106
What percentage of MG patients are seronegative for autoantibodies?
About 10%.
107
Which autoimmune diseases are commonly associated with Myasthenia Gravis?
Hashimoto thyroiditis, rheumatoid arthritis, sarcoidosis, and systemic lupus erythematosus (SLE).
108
Which tumor is most commonly associated with Myasthenia Gravis, and in what percentage of patients?
Thymoma, in 10–15% of patients.
109
Which autoantibody is present in about 85% of Myasthenia Gravis cases?
Antibody against the nicotinic acetylcholine receptor (AChR) at the NMJ.
110
Besides AChR, which other autoantibodies may be involved in MG?
Muscle-specific kinase (MuSK) and low-density lipoprotein receptor-related protein 4 (LRP4).
111
How do AChR autoantibodies interfere with neuromuscular transmission in MG?
They inhibit acetylcholine binding to receptors, reduce receptor availability via aggregation/internalization, and damage the synaptic membrane through complement activation.
112
What is the overall functional effect of antibody-mediated changes at the NMJ in MG?
Progressive weakness of muscle contraction.
113
What are the main clinical forms:
* Ocular myasthenia
* Generalised myasthenia
114
Myasthenia Gravis Clinical Features
- Weakness and fatigue of muscles
- No muscular wasting, no changes in reflexes or sensation
115
How to diagnose Myasthenia gravis diagnosis?
- EMG
- Laboratory investigations
- Imaging (chest CT)
116
How to treat myasthenia gravis?
- Drugs that inhibit acetylcholine esterase
- Rapidly acting immunomodulating agents
- Plasma exchange
- Immunosuppresive agents
- Symptomatic therapy
117
In what context does LEMS most often arise?
As a paraneoplastic disorder, especially with small cell lung carcinoma (50–60% of patients).
118
What is the median age and sex predominance in LEMS?
Median age is 60 years, with 65% of patients being men.
119
In non-tumor–associated LEMS, what are the peak ages of onset?
Around 35 years and again at 60 years.
120
Besides small cell lung cancer, which other tumors can be associated with LEMS?
Prostate carcinoma, thymoma, and lymphoproliferative disorders.
121
Is LEMS a presynaptic or postsynaptic neuromuscular junction disorder?
Presynaptic.
122
What is the pathogenic mechanism of LEMS?
Autoantibodies inhibit presynaptic calcium channels, reducing acetylcholine release into the synaptic cleft.
123
What is the functional result of impaired acetylcholine release in LEMS?
Muscle weakness.
124
LEMS Clinical features
- Proximal muscle weakness
- Autonomic symptoms in 80-90% of patients
- Reduced or absence of tendon reflexes
125
LEMS Management
- Cholinesterase inhibitors
- Potassium channel-clocker
- Plasma exchange
- Immunosuppression
126
Infections with Clostridium tetani (tetanus)
Usually enter the body via puncture wounds
127
Risk groups of tetanus
- Never received tetanus vaccine
- Didnt stay up to date on their 10 year booster shots
128
Tetanus-Pathophysiology
Tetanus toxin travels retrograde to the spinal cord → blocks release of inhibitory neurotransmitters (GABA, glycine) → unchecked motor neuron activity → sustained muscle contraction & spasm.
129
What are the generalised clinical features of tetanus?
- Most common form
- Initial sign is spasm of the muscles of the jaw or "lockjaw"
- Others include painful spasms in other muscles
130
What are the localised clinical features of tetanus?
- Unusual form
- Muscles spasms in a confined area close to the site of injury
- Progression to generalised tetanus can occur
131
What are the cephalic clinical features?
- Rarest form
- Associated with lesions of the head or face or with otitis media
- Incubation period is short, usually 1 to 2 days
132
Tetanus Management
MEDICAL EMERGENCY
- Hospitalization
- Immediate treatment with tetanus immune globulin
- Agents to control muscles spasms
- Aggressive wound care
- Antibiotics
- Tetanus toxoid booster
133
What is the cause for botulism?
Clostridium Botulinum
- Food borne or wound related
134
What is Botulism?
- Pre-synaptic NMJ disorder
- Botulinum toxin inhibits acetylcholine releases producing a flaccid paralysis
135
Disorders of Skeletal Muscle (Myopathies)
- Disease of skeletal muscle which are not caused by nerve disorders
136
What are the types of myopathies?
- Genetic myopathies
- Inflammatory myopathies
- Endocrine myopathies
137
What causes disorders of skeletal muscle?
- Usually, degenerative
- Caused by drug side effects, chemical poisoning or chronic disorder of the immune system
138
Inflammatory Myopathies
- Group of diseases that involve chronic muscle inflammation muscle weakness and sometimes muscle pain
Types:
- Polymyositis
- Dermatomyositis
- Inclusion of body myositis
139
Polymyositis
- Autoimmune disorder
- Inflammatory infiltrates
- Myofiber necrosis and subsequent regeneration
140
Treatment of polymyositis
- Corticosteroids
- Immunosuppressive agents
141
Dermatomyositis
- The most common inflammatory myopathy in children
- Both have an autoimmune basis
142
Clinical features of dermatomyositis
- Skin manifestations (distinct rash occurs before or with the onset of muscle weakness)
- Acute or insidiously progressive
- Proximal leg and arm muscles are usually the earliest and most severely affected
143
Inclusion Body Myositis
- Most common inflammatory myopathy in patients older than 60
- Presence of rimmed vacuoles that contain aggregate of the hyperphosphorylated tau
- Chronic, progressive
- Does not respond well to immunosuppressive agents
144
Microscopic Features
- Mononuclear cell infiltrates
- Fibrosis in edomyosium
- Fatty replacement
145
Pathogenesis of inclusion body myositis
It is unknown
146
Diagnosis of inflammatory myopathies
- Clinical features
- Blood investigations for muscle enzymes and autoantibodies
- EMG to record electrical activity
- USG
- MRI to investigate abnormal anatomy
147
What is the general management of inflammatory myopathies
Medications:
- Corticosteroids
- Immunosuppressants
- Immunoglobulin therapy
Physical therapy
Orthotics and assistive devices
Rest
Systemic Pathology
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