Neuro III (b)

Question 1

the 2 types of peripheral Nerve injury

Answer 1

1) Axonal injuries
2) Demyelinating Neuropathies

Question 2

Morphological hallamrk in Axonal Neuropathies

Answer 2

Decrease in axons’ density –> Decrease in the strength of amplitude of nerve impulses

Question 3

Morphological Hallmark in Demyelinating Neuropathies

Answer 3

Relative normal density of axons and signs of segmental demyelination and repair (remyelination) (axons with thin myelin sheaths and short internodes)

Question 4

patho of Axonal Neuropathies

Answer 4

Direct injury to the axon –> Degeneration of the entire distal portion of the axon –> Secondary myelin loss (Wallerian degeneration)

Question 5

Patho of Demyelinating Neuropathies

Answer 5

Damage to Schwann cells or myelin, but relative axonal sparing –> Occurrence of demyelination in individual myelin internodes (Segmental demyelination)

Question 6

CM of Polyneuropathies

* peripheral nerve injury

Answer 6

Loss of sensation and paraesthesias (“stocking and glove” distribution -> Starts in the toes -> Spreads upward to the knees -> Lastly involves the hands)

* paraesthesias –> tingiling

Question 7

3 types of Peripjeral nerve injury

Answer 7

1) Polyneuropathies (most common)
2) Poluneruritis Multiples
3) Mononeuropathy (involves a single nerver due to trauma or entrapment)

Question 8

A mononeuropathy Syndrom

* peripheral nerve injury (single nerve)

Answer 8

Carpal Tunnel Syndrom
(compression of the median nerve)

Question 9

cause of Gullain-Barre Syndrome

* Rapidly progressive acute demyelinating disorder

Answer 9

1) Infection (e.g. CMV, EBV, HIV, etc.) or vaccine –> Break down of self-tolerance –> Autoimmune response
2) Involvement of both humoral and cellular immune responses

Question 10

Morphological featurs of Gullian-Barre Syndrome

Answer 10

Injury most extensive in the nerve roots and proximal nerve segments

Question 11

CM of Gullian-Barre Syndrome

Answer 11

1) Parethesias (in the hands and feet)
2) Difficulty breathing (due to severe respiratory muscle weakness)
3) Absent or depressed deep tendon relfexes (paralysis)
4) Muscle weakness (begining in the legs and ascends)

Question 12

CM of Chronic inflammatory Demyelinating polyneuropathy

Answer 12

1) Difficulty in walking
2) Weakness
3) Numbness
4) Pain or tingling sensations

Question 13

Microscopic Findings:
* Peripheral nerves with segments of demyelination and remyelination

features of?

Answer 13

Chronic inflammatory demyelinating polyneuropathy

Question 14

the most common peripheral neuropathy

Answer 14

Diabetic peripheral neuropathy
* px w/ long-standing DM

Question 15

Risk factors of Diabetic Peripheral neuropathy

Answer 15

1) Microvascular changes (retinopathy, neuropathy, Nephropathy)
2) Hyperglycaemia
3) Accumulation of Glycosylated end products (HbA1c)
4) Changes in axonal metabolism
5) increased leveles of ROS

Question 16

Type of Diabetic Neuropathies

Answer 16

1) Autonomic Neuropathy: Changes in bowel, cardiac or sexual function
2) Lumbosacral Radiculopathy: Lower extremity weakness and muscle atrophy
3) Distal Symmetric Sensorimotor Polyneuropathy: Paraesthesias and numbness

Question 17

prognosis of Chronic inflammatory demylinating polyneuropathy

Answer 17

Complete recovery (some patients) but Recurrent bouts of symptomatic disease –> Permanent loss of nerve function (most common)

Question 18

Toxic Form of Peripheral Neuropathy: Most susceptible <> —————–, Most pronounced <> ————–

Answer 18

Most susceptible –> Longest axons; Most pronounced –> Distal extremities

Question 19

Examples of Systemic Vasculitides

Answer 19

Polyarteritis nodosa, Churg-Strauss Sy., Wegener granulomatosis

Question 20

Most common clinical picture of Systemic Vasculitides

Answer 20

Mononeuritis multiplex (painful asymmetric mixed sensory and motor peripheral neuropathy)

Question 21

Inherited Form of Peripheral Neuropathy: Most common cause –> Mutations in the ——— gene

Answer 21

PMP22 gene

Question 22

Epi of Myasthenia Gravis

Answer 22

• More common in females
• Thymic hyperplasia (reactive hyperplasia of intra-thymic B cells) –> About 60% of patients
• Thymoma –> 20% of patients

Question 23

cause/ patho of Myasthenia Gravis

Answer 23

Auto-Antibodies blocking the function of Acetylocholine receptors at motor end-plates –> Degradation and depletion of the receptors

Question 24

CM of Myasthenia Gravis

Answer 24

Ptosis (droping eyelids) or Diplopia (double vision), due to weakness in the extra-ocular muscles

Question 25

causes of Lambert-Eaton Syndrome

Answer 25

**Auto-Antibodies** inhibiting the function of **pre-synaptic Calcium channels** -> **Reduction of Acetylocholine release** into the synaptic cleft

Question 26

CM of Lambert-Eaton Syndrome

Answer 26

Paraneoplastic Syndrome in patients with Small Cell Lung Carcinoma (SCLC)

Question 27

Epi of Schwannomas (Neurilemmomas)

Answer 27

* bening * Sporadic (most common); 10% **associated with familial NF2**

Question 28

loc of Schwannomas

Answer 28

* Soft tissues * Internal organs * Spinal nerve roots * **Cranial nerves (Vestibular portion of the 8th nerve**

Question 29

Macroscopic Features: * **Circumscribed masses next to a nerve** * Globualr enlargment of a fascicle * Yellow colouration of the cut surface, due to lipid accumulation Microscopic Findings: * Alternating a**reas of dense (“Antoni A”) and loose (“Antoni B”) texture** * **“Antoni A” **areas: Bland spindle cells arranged into intersecting fascicles * **“Verocay bodies”**: Structures composed of alternating bands of nuclear palisading and anuclear strands between them * **Thick-walled hyalinised vessels** * Possible, presence of haemorrhage or cystic changes features of?

Answer 29

Shwannomas (Neurilemmomas)

Question 30

caues of Neurofibromatois Type 2

Answer 30

**Loss of function mutation of the NF2 gene** affecting **Merlin (Schwannomin) protein**

Question 31

CF of NF2

Answer 31

**Bilateral vestibular Schwannomas** -> Hallmark of Neurofibromatosis Type 2

Question 32

Hallmark of Neurofibromatosis Type 2?

Answer 32

**Bilateral vestibular Schwannomas**

Question 33

------------ : Familial condition associated with multiple Schwannomas, Ass. w/ the Absence of vestibular Schwannomas

Answer 33

Schwannomatosis

Question 34

Microscopic Findings: * **Non-encapsulated** tumours * Haphazard cellular growth pattern * **Admixture of Schwann cells w wavy nuclei, mast cells, fibroblast-like cells and perineurial-like cells** * Background **stroma**: Loose wavy or dense **collagen bundles** or even **myxoid consistency** features of?

Answer 34

Neurofibromatosis Type 2

Question 35

localized Cutaneous Neurofibromas can exist as?

Answer 35

* solitary lesions or multiple in the context of NF1 * Superficial nodular or polypoid masses

Question 36

Pathogonomic (symptom/sign) of NF1

Answer 36

**Plexiform Neurofibromas**

Question 37

Microscopic Findings: * Presence of residual axons found among the neoplastic cells * Proliferation of schwann cells and fibroblasts * **Enlargement of the nerve** * **Intact perineurium** * Classic **“bag of worms appearance”** features of?

Answer 37

Plexifrom Neurofibromas

Question 38

Diffuse Neurofibromas are ass w/?

Answer 38

NF1

Question 39

Microscopic findings: * Extensive infiltration of the dermis and subcutis * **Subcuataneous masses** * **Marked expansion of dermal tissue** features of?

Answer 39

Diffuse Neurofibromas

Question 40

Neurofibromatosis Type 1 is AKA?

Answer 40

Von Recklinghausen disease

Question 41

Genetic predisposition of NF1

Answer 41

**AD** ; Mutations in the **tumour suppressor gene Neurofibromin**

Question 42

CM of NF1

Answer 42

1) Learning disabilities 2) Seizures 3) Skeletal abnormalities (e.g. **scoliosis**) 4) Vascular abnormalities with arterial stenoses 5) Pigmented nodules of the iris **(Lisch nodules)** 6) Pigmented skin lesions (axillary freckling and **café au lait spots**) 7) **Optic Glioma** 8) **Neurofibromas** 9) **Bone defects**

Question 43

who is likely to develop Malignant Peripheral Nerve Sheath tumours?

Answer 43

NF1 px

Question 44

patho of Malignant Peripjeral nerve Sheat tumours

Answer 44

May originate from transformation of a Neurofibroma, usually of the plexiform type

Question 45

cause of Traumatic Neuroma

Answer 45

Previous injury of a peripheral nerve

Question 46

patho of Traumatic Neuroma

Answer 46

* **Transection (divides) of axon** --> Activation of regeneration mechanism --> Sprouting and elongation of processes (from the proximal axonal stump) * **Severe injury** --> Disruption of the peri-neurial sheath --> **Failure of proximal end to “meet” the distal end of the transected nerve** --> Induction of a **Schwann cell proliferation** --> Development of a **haphazard mixture of axons, Schwan cells and connective tissues**

Question 47

Occular Disroders

Answer 47

1) Conjunctivitis 2) Retinopathy of prematurity 3) Retinitis Pigmentosa 4) Diabetic Retinopathy 5) Senile Macular Degeneration 6) Glaucoma 7) Retinoblastoma

Question 48

Cause of Conjuctivitis

Answer 48

**Adenovirus** (most common), bacteria

Question 49

Prgnosis of Retinopathy of Prematurity

Answer 49

Blindness

Question 50

casue of Retionopathy of prematurity

Answer 50

Toxicity of oxygen, administered because of NRDS (Newborn respiratory distress syndrome)

Question 51

CM of Retinitis Pigmentosa

Answer 51

1) Retinal pigmentation 2) Peripheral vision loss **(“Tunnel vision”)** and progressive loss of Central Vision

Question 52

cause of Diabetic Retinopathy

Answer 52

1) Non-proliferative: - **Micro-aneurysms, haemorrhages**, **soft** (cotton-wool) **exudates** (micro-infarcts) and **hard exudates** (protein from damaged capillaries) 2) Proliferative: - **Neo-vascularisation and fibrosis** - Possible progression to **haemorrhage** and **retinal detachment**

Question 53

patho of Senile Macular Degenration

Answer 53

Loss of central vision and pigmentary changes or haemorrhage in the macula

Question 54

patho/CM of Open Angle Galucoma

Answer 54

1) **Open Angle Glaucoma**: Gradually increasing intraocular pressure --> **Visual impairment** --> **Blindness**

Question 55

patho/CM of Angle-Closure Galucoma

Answer 55

Angle-Closure Glaucoma: * Narrow anterior chamber angle * Increase in intraocular pressure on dilatation of pupil

Question 56

symptoms of open angle Glaucoma

Answer 56

1) Gradual loss of peripheral (side to side & up/down) visions, usually in both eyes 2) Tunnel vission

Question 57

Smptoms of Closed angle Glaucoma

Answer 57

1) sudden,sever blurred vision 2) Severe pain- often affecting one eye at a time

Question 58

Risk factors of Glaucoma

Answer 58

1) increased eye pressure 2) High bp 3) Family history of Glaucoma 4) >60 yrs

Question 59

Gentic predispostion of Retinoblastoma

Answer 59

Homozygous deletion of **Rb gene**

Question 60

Explain the "two hit" hypothesis of tumour development in Retinoblastoma

Answer 60

1) First “hit”: Inherited deletion in germ cells (familial cases) or somatic mutation (sporadic cases) 2) Second “hit”: Somatic mutation (both familial and sporadic cases)

Question 61

Signs of Retinoblastoma

Answer 61

1) swollen eyes 2) shrunken eyes 3) A red, sore or swollen eye w/o infection 4) A white refelction in the pupil

Question 62

Microscopic features: - Multiple foci of necrosis - Numerous apoptotic cells - True rosette - scant cytoplasm - **Flexner-Wintersteiner rosette** - Round to oval nuceli and finely granualr chromattin features of?

Answer 62

Retinoblastoma