Quiz 5, Nervous System Flashcards by Matthew Hicks

When a nerve injury occurs what response promotes the resealing of severed parts of the myelin sheath?

An initial calcium influx

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What is a process that results when a nerve fiber is cut or crushed, in which the part of the axon separated from the neuron’s cell body degenerates distal to the injury?

Wallerian degeneration

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Which three cranial nerves account for the majority of mononeuropathies?

7 - Facial
5 - Trigeminal
3 - Occulomotor

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What is the MC cranial nerve neuropathy?

Bell’s Palsy (acute idiopathic facial nerve neuropathy)

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What is the main symptom in Bell’s palsy?

Unilateral facial weakness that begins abruptly and preceded or accompanied by pain behind the ear.

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How do you differentiate Bell’s palsy from a stroke?

In a stroke the patient can still wrinkle their forehead, in bell’s palsy they cannot

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What condition is a distinctive facial pain syndrome felt over the maxillary or mandibular areas?

Trigeminal neuralgia (tic douloureux)

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What are some nutritional deficiencies and their related neuropathies?

Beriberi (B1) - alcohol
B6 deficiency - ?
B6 excess - ?
B12 - ?

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What blood vessel is most often responsible for neurovascular compression upon the trigeminal nerve root?

Superior cerebellar artery

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What condition is known for the “down ‘n out” symptoms?

Oculomotor nerve palsy (3rd CN)

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Which nerve is compressed and entrapped with carpal tunnel syndrome?

Median n.

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What can long standing carpal tunnel syndrome lead to?

Permanent nerve damage with constant numbness, atrophy/weakness of thenar eminence.

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Where is the most common site of ulnar nerve entrapment?

Elbow, followed by wrist.

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What is the “claw hand” deformity indicate?

Ulnar nerve injury. Effects 4th and 5th digits.

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What is meralgia paresthetica characterized by?

Sensory symptoms in the distribution of the lateral cutaneous nerve of the thigh

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Meralgia paresthetica is usually attributed to compression of the lateral cutaneous nerve by what structure?

Inguinal ligament as it passes from the retroperitoneum to the anterior thigh

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In what condition is peripheral neuropathy most commonly noted?

Diabetes mellitus

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What types of diabetes related neuropathies are most common?

Distal, symmetrical and sensorimotor neuropathies

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What is the chief pathologic finding in uremic neuropathy?

Axonal degeneration

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What is the most common cause of acute generalized paralysis in the U.S.?

Guillain-Barre syndrome

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What is the rate of onset in CIDP compared to GBS?

CIDP is insidious, GBS is more rapid initially

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How common is autonomic and respiratory involvement in CIDP compared to GBS?

Common in GBS

Unusual in CIDP

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What is the fundamental pathologic event in Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP)?

Stripping of myelin from axons by macrophages, which slows or blocks nerve impulse conduction.

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Polyneuropathy characterized by amyloid deposition in nerve generally occurs in one of what two settings?

Systemic or familial amyloidosis

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What mycobacterial disease, the majority of which occur in tropical and sub-tropical regions, is one of the most common causes of polyneuropathy worldwide?

Leprosy

How does Borrelia burgdorferi stain?

Neither gram-negative nor gram-positive

What cranial neuropathy is most common in lyme disease and what is it commonly misdiagnosed as?

Facial (bilateral) | Idiopathic Bell's palsy

What is the most common viral pathogen affecting the PNS?

Varicella-zoster

What condition is caused by glial cells that myelinate axons proliferating and compressing nerves?

Schwannoma

Vestibular schwannomas may occur as an idiopathic process or can occur as part of what syndrome?

Neurofibromatosis (type 1 or 2)

What is a common, benign, spindle cell tumor of peripheral nerves?

Neurofibroma (solitary tumor suggests that the pt does not have neurofibromatosis)

What condition follows the mutation of neurofibromin, a tumor suppressor gene?

Neurofibromatosis type 1

Which type of neurofibromatosis is more common (90%) and also known as von Recklinghausen disease?

Type 1

How do you differentiate type 1 from type 2 neurofibromatosis?

Type 1: Entire 8th nerve, cutaneous neurofibromas, cafe au lait spots Type 2: bilateral acoustic neuromas > hearing loss

What condition follows the mutation of the protein, merlin?q

Neurofibromatosis type 2

What kind of tumors are characterized by elongated cells in parallel bundles?

Perineuromas

What is a malignant schwannoma that usually arises from major nerves of the neck, forearm, lower leg, or buttocks?

Malignant peripheral nerve sheath tumor (MPNST)

What are the histology keywords to associate with a malignant peripheral nerve sheath tumor that you have no hope of remembering after this test?

``` Monomorphic serpentine cells palisading large gaping vascular spaces perivascular plump cells geographic necrosis with tumor palisading at edges ```

What type of birth defects are most common?

Those involving the brain (although those involving the heart are the MC defects leading to death)

What is the absence of brain formation?

Anencephaly

What is diminished brain size?

Microcephaly

What are four potential causes of microcephaly?

Fetal Alcohol syndrome Trisomy 18 Congenital rubella Congenital HIV

What is the most common cause of hydrocephalus?

Obstruction of normal CSF flow (it can also be caused by CSF production or reabsorption problems)

Which spina bifida refers to a condition of a missing portion of a posterior vertebral body?

Occulta

Which spina bifida refers to herniation of the meninges but not the cord?

Meningocele

Which spina bifida refers to the herniation of the meninges and the spinal cord?

Meningomyelocele (myelomeningocele)

What are some conditions seen with ABOVE normal levels of maternal alpha fetal protein?

Neural tube defects including spina bifida, anencephaly, and abdominal wall defects

What are some conditions seen with BELOW normal levels of maternal alpha fetal protein?

Down's syndrome and Trisomy 18

What is the most common type of cerebral palsy?

Spastic, hypertonic musculature stemming from damage to the motor cortex, corticospinal tract or pyramidal tract

What is the most common finding on autopsy of patients with cerebral palsy?

Periventricular leukomalacia (necrosis around the ventricles)

With periventricular leukomalacia what becomes of the damaged areas?

Partly cystic and partly gliotic (gliosis)

Which is more commonly the cause of meningitis, viral or bacterial infection? and which is more serious?

MC: Viral [resolves w/o tx] 2nd bacterial [may result in death/brain damage despite tx] (can also be caused by cancer or trauma)

What bacteria is MC cause of meningitis in NEONATES?

E. Coli

What bacteria is MC cause of meningitis in INFANTS/CHILDREN?

Neisseria meningococci

What bacteria is MC cause of meningitis in ADOLESCENTS/ADULTS?

Neisseria meningococci

What bacteria is MC cause of meningitis in OLDER ADULTS?

Strep. pneumonia

What does CSF analysis reveal in bacterial meningitis for CSF pressure?

> 180 mm H2O

What does CSF analysis reveal in bacterial meningitis for WBC count?

10 - 10,000/ uL with notable neutrophil predominance

What does CSF analysis reveal in bacterial meningitis for glucose and CSF to serum glucose ratio?

What does CSF analysis reveal in bacterial meningitis for protein?

> 4.5 mg/dL

What does CSF analysis reveal in bacterial meningitis for gram stain and culture?

Both are positive in a majority of cases

What test is best for identifying viral meningitis?

PCR

What test is best for identifying H. flu?

Latex agglutination

What is typically seen on histology of Neisseria meningitidis?

Gram negative diplococci within a neutrophil | Neutrophilic exudate, dilated vessels

What are some sequelae of meningococcal meningitis?

``` Permanent brain damage Hydrocephalus Deafness Paralysis of various muscles Myocarditis Waterhouse-Frederichsen syn. Death ```

What clinical sign often precedes other symptoms with meningococcal meningitis?

Rapidly spreading petechial rash

Although the development of a vaccine has greatly reduced its incidence what microorganism causing meningitis typically affects children under 4 following URI?

Haemophilus influenzae

What two viruses account for most of the cases of aseptic meningitis?

Coxsackie B and echovirus

What yeast found in soil around the world causes meningitis especially in the immunocompromised?

Cryptococcal neoformans (confirmed by CSF stains using India ink, culture, antigen test)

What does viral encephalitis most commonly arise as a complication of?

Common systemic viral infections

What type of viruses are predominantly noted in spring and summer months?

Arthropod-borne (arboviruses)

What viruses peak in the late summer?

Enteroviruses

When are mumps and varicella prevalent?

Spring

What type of virus is the MC cause of viral meningitis? 2nd? 3rd?

Enteroviruses 2nd: HSV 2 3rd: VZV (among cases where the cause is identified, which is a minority of them)

Encephalitis due to HSV infection characteristically involves what part of the brain?

Temporal lobes

What is definitive for diagnosis of carcinomatous meningitis?

Tumor cells detected in the CSF

What is the most frequent histologic type of meningeal tumor?

Adenocarcinoma

What is seen histologically in a aspergillus brain abscess?

Slender hyphae

What is the most common organism found in brain abscesses?

Streptococcus

Are gram negative or positive organisms more common in infants with brain abscesses?

Negative

What condition is an infection of the CNS by larvae of the pork tapeworm and what is the name of the tapeworm?

Neurocysticercosis | Taenia solium

What is the definitive host for taenia solium?

Humans, pigs are intermmediary

If a human ingests eggs from taenia solium through fecal contaminated food what is the condition if the resulting larvae do not encyst in the brain?

Cysticercosis