PNS disorders Flashcards
Peripheral senses with heavily myelinated fibers
Touch
Vibration
Proprioception
Peripheral senses with less myelinated or unmyelinated fibers
Pain and temperature
Mildest grade of peripheral nerve injury where axonal continuity is maintained
Neuropraxia
Causes of neuropraxia
Compression
Ischemia
Metabolic derangement
Demyelinating disease
Peripheral nerve injury grade where axon is damaged, but there is preservation of surrounding CT
Axonotmesis
Wallerian degeneration
Axon and myelin degeneration distal to site of injury
Characteristics of central chromatolysis
Swelling of neuronal body
Disruption of Nissl granules in center
Displacement of nucleus to periphery
Peripheral nerve injury grade characterized by complete nerve transection
Neurotmesis
Benign painful nodular thickening that can be produced by failure of the outgrowing axons to find their distal target
Traumatic neuroma
Acute peripheral neuropathy timing
<4 weeks
Subacute peripheral neuropathy timing
4-8 weeks
Chronic peripheral neuropathy timing
> 8 weeks
Pattern of peripheral nerve injury characterized by several nerves in a haphazard fashion
Mononeuropathy multiplex
Another name for Guillain Barre syndrome
Acute inflammatory demyelinating polyneuropathy (AIDP)
Rapidly evolving, areflexic, motor paralysis with or without sensory disturbance of PNS. Ascending, symmetric, flaccid paralysis
Guillain Barre syndrome
Complication of lower cranial nerve involvement in Guillain Barre syndrome
Causes bulbar weakness with difficulty in handling secretions and maintaining an airway
Antibodies implicated in Guillain Barre syndrome
Against unidentified myelin antigens and GM1/GD1b
Histology shows endoneurial inflammatory infiltration in PNS
Guillain Barre syndrome
Nerve conduction study findings in Guillain Barre syndrome
Slow conduction velocity
Prolonged distal latency
Preserved amplitude
CSF analysis shows albumino-cytological dissociation with normal cell count and elevated proteins. There is little to no CSF pleocytosis.
Guillain Barre syndrome
Treatment for Guillain Barre syndrome
Plasmapheresis and IV immunoglobulin
Types of infectious polyneuropathies
Leprosy
Diphtheria
Shingles
Pathophysiology of leprosy polyneuropathy
Schwann cells are invaded by Mycobacterium leprae
Segmental demyelination, remyelination, and loss of both myelinated and unmyelinated axons, often affecting superficial cutaneous nerves of the ears and distal limbs
Leprosy
Pathophysiology of diphtheria polyneuropathy
Exotoxin
Mutation in CMT type 1
Peripheral myelin protein PMP22 in chromosome 17p12 leading to formation of unstable myelin
Pt presents between first to third decade with distal symmetrical leg weakness and calf atrophy, sensory loss, and pes cavus.
CMT type 1
Nerve conduction study findings in CMT type 1
Decreased conduction velocity
Nerve biopsy shows segmental demyelination and remyelination with onion bulb formations
CMT type 1
Defect in CMT type 2
Mitofusin 2
Secondary vascular changes in diabetic polyneuropathy
Diabetic microangiopathy
Endoneurial arteriole hyalinization
Pt presents with distal, ascending, symmetric, sensorimotor neuropathy with loss of pain and temperature. Non-healing ulcers are present on the feet.
Diabetic polyneuropathy
Autonomic features of diabetic polyneuropathy
Postural hypotension
Erectile dysfunction
Gastroparesis
Nerve biopsy findings in diabetic neuropathy
Axonal degeneration
Endothelial hyperplasia
Occasional perivascular inflammation
EMG findings in diabetic neuropathy
Reduced amplitudes
Mild to moderate slowing of conduction velocities
Characteristics of neuropathy associated with uremic nephropathy
Length-dependent numbness and tingling
Allodynia
Mild distal weakness
Allodynia
Pain to a stimulus that does not normally produce pain
Characteristics of generalized sensorimotor neuropathy associated with chronic liver disease
Numbness and tingling
Minor weakness in the distal aspects
Sural nerve biopsy findings in neuropathy associated with chronic liver disease
Segmental demyelination
Axonal loss
Presentation of neuropathy associated with vit B12 deficiency
Subacute paresthesias in hands and feet
Loss of vibratory and position sense
Progressive spastic and ataxic weakness
Degeneration of spinocerebellar tract, corticospinal tract, and dorsal columns
Vit B12 deficiency
Progressive peripheral nerve injury due to thiamine deficiency
Alcoholic neuropathy
Deficiency associated with isoniazid therapy
Vit B6
Paraneoplastic neuropathy of direct infiltration is associated with this cancer
Small cell lung cancer
Target antigens in direct infiltration paraneoplastic neuropathy
HuD, HuC, Hel-N1
Family of RNA-binding proteins expressed by neurons
Antibodies detected in serum in direct infiltration paraneoplastic neuropathy
Anti-Hu antibodies
Mononeuropathy associated with neoplasm at the apex of the lung
Brachial plexopathy
Mononeuropathy associated with malignant neoplasms in the pelvis
Obturator palsy
Reparative lesion at the site of traumatic injury of peripheral nerves that presents as a painful/tender, firm nodule near the stump of the injured nerve
Traumatic neuroma
Gross appearance of traumatic neuroma
Circumscribed, grayish-white appearance
Disorganized proliferation of nerve fascicles, Schwann cells, and fibroblasts embedded within the scar tissue adjacent to the cut ends of the nerve
Traumatic neuroma
Inheritance of spinal muscular atrophy
Autosomal recessive
Mutation in spinal muscular atrophy
Defect in SMN1 gene on chromosome 5q causing apoptosis of LMNs
Other names for SMA 1
Infantile SMA
Werdnig-Hoffman disease
Other names for SMA III
Juvenile SMA or Kugelberg-Welander disease
Nerves not affected in SMA
CN III, IV, and VI
Sacral motor neurons
Sensation is preserved
