PNS Pathology Flashcards
Branches of the Sciatic nerve
1) Tibial Nerve
2) Common peroneal nerve (becomes superficial and deep)
What is the result of damage to the tibial nerve?
1) Loss of plantar felxion (due to innervation of gastrocnemius, soleus, ect)
2) Loss of inversion (due to innervation of the tibialis posterior)
3) Provides sensory innervation for the plantar surface of the foot
Branches of the Brachial plexus
1) Musculoskeletal (C5-7)
2) Axillary (C5-6)
3) Median (C6-T1)
4) Ulnar (C8-T1)
5) Radial (C5-8)
Parts of the Brachial Plexus
1) Roots
2) Trunks
3) Division
4) Cords
5) Branches
What causes segmental demyelination of peripheral neurons?
1) Damage to the Schwann cell
2) Damage to the myelin sheath
What is a result of axonal degeneration?
1) Denervation atrophy
What is the morphology of denervation atrophy?
1) Decreased muscle fiber size
2) Fibers have a triangular shape
3) Round zone of disorganized myofibers in the center of the cell (target fiber)
Inflammation and segmental demyelination of spinal nerve roots and peripheral nerves due to an immune mediated process
Guillain-Barre Syndrome
What is the dominant histopathologic finding in Guillan-Barre Syndrome?
1) Inflammation of the peripheral nerve
2) Most intense inflammation occurs at the spinal cord and cranial roots
What is the earliest manifestation of Diphtheria in regards to neurologic symptoms?
1) Loss of sensory ganglia due to the incomplete blood brain barrier
2) Loss of proprioception and vibratory sense
What does myobacterium leprae infect in the nervous system? What type of leprosy is worse?
1) Infect the Schwann cells and cause demylination
2) Lepromatous leprosy
What cells are active in lepromatous leprosy? tuberculoid leprosy?
1) TH2
2) TH1 (activate macrophages)
Reactive infection that results in painful, vesicular skin eruptions in the distribution of the sensory dermatomes in the thoracic and trigeminal region
Varicella-Zoster virus
What is another name for Hereditary Motor and Sensory Neuropathy Type I?
Charcot-Marie-Tooth disease
What are findings of Charcot-Marie-Tooth Disease?
1) Progressive muscular atrophy of the leg below the knee
2) Pes cavus
What are causes for Charcot-Maire-Tooth disease (Type 1A and B)
1) Type 1A = segmental trisomy of chromosome 17
2) Type 1B = mutation of MPZ gene on chromosome 1
What are the Hereditary Neuropathies?
1) Charcot-Marie-Tooth Disease (HMSN type I)
2) HMSN type II
3) Dejerine-Sottas Neuropahty (HMSN type III)
What is hypertrophic neuropahty?
1) Enlargement of peripheral nerves due to layers of schwann cell hyperplasia
2) Occurs in hereditary demyelinating diseases
Slowly progressive autosomal recessive hereditary neuropathy that presents with delay of developmental milestones, absent DTRs and trunk/limb atrophy; Loss of axons
Dejerine-Sottas Neuropahty
What is the most common clinicopathologic pattern of peripheral neuropathy found in Adult onset diabetes?
1) Distal symmetric sensory and motor neuropathy
What are the common presentations observed in Diabetic patients neurologically?
1) Distal symmetric sensory and motor neuropathy
2) Loss of pain sensation
3) Loss of motor function
4) Autonomic dysfunction such as postural hypotension, sexual dysfunction, and failure to completely empty the bladder
What vitamin deficiencies result in axonal neuropathies?
1) Thiamine (B1)
2) B6
3) B12
4) Vitamin E
What is the cause of a traumatic neuroma (pseudoneuroma)?
1) the growth of an axon after trauma that does not have a correctly positioned distal segment
What is Myasthenia gravis commonly associated with?
1) Thymoma
2) Thymus hyperplasia
What is the cause of Myasthenia gravis
1) Autoimmune attack on the acetylcholine receptors located in the neuromuscular junction
Gram positive spore produing rod and is anaerobic; causes flaccid paralysis
Clostridium botulinum
Gram positive spore producing rod and is anaerobic; causes contraction paralysis
Clostridium tetanii
How does Clostridium botulinum exotoxin work?
1) It works by preventing the release of acetylcholine from the presynaptic nerve terminals
How does Clostridium tetani exotoxin work?
1) Exotoxin is taken up by the CNS and inhibits the inhibitory interneurons
2) Results in the unregulated contraction of muscles
Pt. presents with photophobia, fever, headache, neck stiffness, and irritability; LP shows purulent CSF with increased protein, low glucose, and PMNs >90,000
Bacterial meningitis
How do infectious brain abscesses occur?
1) Due to direct implantation
2) Local extension
3) Hematogenous spread
What are some predispositions for infectious brain abscesses to occur?
1) Bacterial endocarditis
2) Immunosuppresion
3) Chronic pumonary sepsis
4) Congenital heart disease
Where does CMV have a tendency to infect? What type of population does it infect?
1) Localize in the paraventricular subependymal regions of the brain
2) Fetuses and immunosuppressed
Cytoplasmic, eosinophilic inclusions that can be found in the pyramidal neurons of the hippocampus and purkinje cells of the cerebellum with Rabies virus infection
Negri bodies
Where are Negri bodies found?
1) In sites devoid of inflammation
2) Pyramidal neurons of the hippocampus
3) Purkinje cells of the cerebellum
What are pathognomonic for Rabies infection?
1) Negri bodies
How is rabies contracted?
1) Wound bite
2) Travels up the peripheral nerves into the CNS
What is the incubation time of rabies dependent upon?
1) The travel of the rabies virus from the peripheral nerves to the cns
What virus causes the presence of microglial nodules in a chronic inflammatory reaction? What do the microglial nodules contain?
1) HIV
2) Multinucleated giant cells
What is the cause of progressive multifocal leukoencephalopathy? In what setting does progressive multifocal leukoencephalopathy occur?
1) JC virus
2) Occurs exclusively in the immunosuppressed
What does the JC virus infect? What is the result?
1) Oligodendrocytes
2) Demyelination
What is the result of damage to Schwann cells?
Segemental demeylination
Inflammation and demyelination of spinal roots and peripheral nerve; T cell immune mediated; results in ascending paralysis
Guillain-Bare Syndrome
Lesions with central liquefactive necrosis surrounded by fibrosis and swelling
Brain Abscess
What does the JC virus infect?
Infects oligodendrocytes
What areas of the brain are affected by Herpes Simplex Virus type 1?
Encpehlaitis of the inferior/medial regions of the temporal lobe and orbital gyri of the frontal lobe
Infection that causes the destruction of anterior horns resulting in flaccid paralysis
Poliomyelitis
What disease presents just like poliomyelitis?
Werdnig-Hoffman disease
Cause of Tabes dorsals? What are findings?
1) Tertiary Trepenoma palidum infection
2) Loss of proprioception and vibration sense
What limits the ability of the axons to regenerate?
Movement of the tubulin, actin, and intermediate filaments
Chronic meningitis involving the base of the brain, gummas
Meningovascular neurosyphilis pattern
What are the patterns of neurosyphilis?
1) Meningovascular neurosyphilis
2) Paretic neurosyphilis
3) Tabes dorsalis
Invasion of organism in the frontal lobe of the brain that leads to mental deficits, general paresis (general paresis of the insane);
Paretic neurosyphilis
Damage to the sensory nerves in the dorsal roots and columns resulting in proprioception and pain loss
Tabes dorsalis
Pt. experiencing insomnia, headaches, periodic agitation, persistant fever, painful spasms with swallowing or inspiration, and dysphagia. Four weeks ago pt. explored a cave. Later pt. progresses to a coma. What does he have? What could have been done to prevent this?
1) Rabies encephalitis
2) Prophylactic killed vaccine
Autoimmune condition that destroys schwann cells leading to inflammation and demyelination of peripheral nerves and motor fibers; ascending paralysis
Guillan Barre (Acute inflammatory demyelinating polyradiculopathy)
