Term
| what level does the spinal cord end at in adults? |
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Definition
| L1 - which is why it is safe to do a lumbar puncture at L4/5 in adults (infants - lower) |
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Term
| what happens w/spinal injuries lower than T12? |
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Definition
| the deficit will likely occur lower than just at that level |
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Term
| what is the preferred imaging for the spinal cord? |
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Definition
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Term
| what makes up the posterior column? |
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Definition
| the fasciculus gracilis (more medial): vibration and position upper extremity. and the fasiculus cuneatus (more lateral): same for the upper extremity |
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Term
| what does the lateral corticospinal tract do? |
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Definition
| voluntary movement = pyramidal tract |
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Term
| what does the lateral spinothalamic tract do? |
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Definition
| ascending sensory information |
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Term
| where are the cell bodies of the LMN located? |
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Definition
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Term
| what is indicative of UMN pathology (stroke)? |
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Definition
| no atrophy, spasticity, increased DTRs, and present babinski |
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Term
| what is indicative of LMN pathology (spinal cord injury, myasthenia gravis, etc)? |
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Definition
| atrophy, flaccidity, decreased/absent DTRs, and decreased/absent babinski (also possible if problem is at dorsal root ganglion) |
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Term
| what characterizes the function and pathway of the posterior columns? |
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Definition
| these allow vibratory, position, two point discriminate and discriminative touch sensation. the receptors are located in the joints or pacinian corpuscles then travel up the spinal cord (through f. gracilis if legs and f. cuneatus if arms). they cross over at the internal arcuate fibers in the cervical spinal cord and then travel up through the brain as a part of the medial leminiscus, synapse in the thalamus and radiate out to the post-central gyrus. |
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Term
| what characterizes the function and pathway of the spinothalamic tract? |
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Definition
| these begin as free nerve endings in the periphery, enter the cord and cross after 1-2 levels, go up to the thalamus, then radiate out to the postcentral gyrus. |
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Term
| what is brown-sequard syndrome? |
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Definition
| the result of a hemisection of the spinal cord where: the corticospinal lesion produces spastic paralysis on the same side of the body below the level of the lesion (due to loss of moderation by the UMN). at the level of the lesion, there will be flaccid paralysis of the muscles supplied by the nerve of that level (since lower motor neurons are affected at the level of the lesion). the lesion to fasciculus gracilis or fasciculus cuneatus results in ipsilateral loss of vibration and proprioception (position sense) as well as loss of all sensation of fine touch. the loss of the spinothalamic tract leads to pain and temperature sensation being lost from the contralateral side beginning one or two segments below the lesion. |
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Term
| what are the clinical manifestations of spinal cord disease? |
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Definition
| weakness, difficulty walking, spinal pain (most are extradural compressive disorders), motor abnormalities (paraplegia [legs], quadriplegia [leg+arms], and abnormal reflex and tone), sensory abnormalities (spinal cord level), and bladder dysfunction. |
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Term
| what does myelopathy mean? |
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Definition
| injury to the spinal cord |
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Term
| what does intramedullary mean, when talking about the spinal cord? |
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Definition
| w/in the spinal cord parenchyma (vs an extramedullary meningoma, abscess, hemorrhage) |
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Term
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Definition
| metabolic, infections, traumatic, congenital, hereditary, vascular, immune, neoplastic, drugs, idiopathic, degenerative/demyelinating, other. (mitch vindi do...) |
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Term
| what characterizes the vascular anatomy of the spinal cord? |
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Definition
| there is one anterior artery and 2 posterior spinal arteries. the anterior artery supplies the anterior 2/3 of the spine, and therefore requires help from 2 collateral channels to aid in perfusion: one upper and one lower thoracic. the lower thoracic collateral is called the artery of adamkiewicz. |
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Term
| what is anterior artery syndrome? what causes this? |
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Definition
| the anterior artery is particularly susceptible to ischemia and if this occurs, the pt will experience lower body weakness and since it supplies the spinothalamic tract = there is a loss of pain/temp sensation. since the dorsal columns are supplied by the posterior arteries vibration and proprioception are spared. etiologies: disruption/thrombosis of the artery of adamkiewicz or aortic aneurysm w/dissection. |
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Term
| what is spinal cord trauma due to in the the cervical region? |
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Definition
| compression and hyperextension |
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Term
| what is spinal cord trauma due to in the the thoracolumbar region? |
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Definition
| compression and hyperflexion |
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Term
| what characterizes acute spinal shock (1-6 wks)? |
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Definition
| flaccid paralysis, reduced DTR's, smooth muscle hypofunction (decreased sweating, piloerection, dependent edema, atonic bladder, ileus) (LMN-like) |
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Term
| what characterizes chronic spinal trauma? |
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Definition
| increasing reflexes/tone, involuntary spasms, and hyperactive bladder/bowel w/involuntary emptying. (UMN-like) |
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Term
| what is central spinal cord syndrome? |
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Definition
| this occurs on a backdrop of cervical degenerative cord arthritis, which causes prominent spurring. w/traumatic hyperextension, the spurs can be driven into the spinal cord = central hemorrhage. the LMNs (lateral corticospinal tracts) are located w/in this field of injury and if damaged = get mainly damage to the arms and hands while the legs are generally spared (if involved, usually UMN). thus pts have weak, dangling, LMN weakness in the upper extremities. the posterior columns are also usually preserved. |
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Term
| what classifies spinal cord tumors? |
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Definition
| 55% are extradural, most of which are metastatic (like prostate or breast CA). 40% are intradural (still extramedullary), and are neurofibroma/meningoma. 5% are intramedullary: astrocytoma, ependymoma. |
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Term
| what are the clinical manifestation of spinal cord tumors? |
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Definition
| back/neck pain (usually precedes onset of neurologic signs and symptoms in *extradural tumors), pure spinal cord syndrome (no radicular s/s: *intramedullary tumors, dissociated sensory loss), radicular-spinal cord syndrome, *rapidly progressive, and froin syndrome (increased CSF protein). |
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Term
| what characterizes cervical astrocytomas? |
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Definition
| these intramedullary spinal cord tumors appear as large cystic masses on axial spinal MRIs |
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Term
| what characterizes thoracic meningiomas? |
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Definition
| these intradural, extramedullary tumors compress the spinal cord in a C-shape |
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Term
| what characterizes thoracic lymphoma? |
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Definition
| generally metastatic tumors gain access to the vertebral body, but these grow w/in the periaortic gutter - then travel through the neuroforamen and create a *dumbbell shape. they do not cause bony destruction. |
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Term
| what is the most common form of spinal cord tumor? |
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Definition
| metastatic spinal cord tumor - usually from the prostate or breast. pts will generally experience back pain for several weeks before spinal cord syndrome presents. this should be visible as involvement/destruction of vertebral bodies on MRI. |
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Term
| how are spinal cord tumors treated? |
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Definition
| early dx is important (tx w/high index of suspicion - use many MRIs). primary CA tx: surgical resection/decompression. secondary CA tx: high dose corticosteroids, *urgent radiation therapy*, sx for uncertain dx/progression/recurrence after maximal radiation therapy. |
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Term
| what is the most common spinal cord infection? |
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Definition
| epidural abscess usually by staph aureus, from contiguous extension (skin abscess/boil/back sx -> osteomyelitis -> spinal cord involvement) or hematogenous spread. if these abscesses are small enough, sx is likely unecessary and IV antibx may be sufficient. |
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Term
| what characterizes incidence of poliomyelitis? |
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Definition
| polio is a ubiquitous enterovirus frequently causing gastroenteritis, which most people are vaccinated against (to protect against CNS spread). |
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Term
| what does poliomyelitis affect? |
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Definition
| poliomyelitis means “inflammation of gray matter” exclusively affecting the *LMN and *anterior horn cells and *bulbar neurons in lower brain stem |
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Term
| what is the clinical course of poliomyelitis? |
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Definition
| anterior horn cells/LMNs are involved = limb weakness, atrophy, hyporeflexia, thoracic regionkyphoscoliosis, and respiratory difficulty. cranial nerve nuclei may also be affected = dysarthria, dysphagia, tongue atrophy, speech articulation problems (hypoglossal nucleus, pharyngeal nucleus). sensory exam = normal. |
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Term
| what characterizes neurosyphilis/tabes dorsalis? |
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Definition
| involvement of the dorsal columns (gait ataxia [wide based gait], romberg sign), dorsal roots (hyporeflexia), and bladder hypotonicity. |
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Term
| what nutritional/metabolic disease commonly affects the spinal cord? tx? |
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Definition
| subacute combined (posterior column+corticospinal tracts) degeneration; which is due to a vit B12 deficiency. clinically it affects the posterior columns (loss of vibration/position sense), corticospinal tracts (spastic paraparesis/quadriparesis), and may also affect the peripheral/optic nerves. the lack of B12 leads to demyelination of the lateral/posterior columns - but this is reversible w/B12 supplementation. |
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Term
| what is friedreich's ataxia? |
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Definition
| a genetic (autosomal dominant/recessive forms) disorder which leads to a slow progressive ataxia through demyelinating effects on the posterior columns (decreased position sense), cerebellum (ataxia), dorsal root ganglia (decreased reflexes), and corticospinal tracts (weakness, babinski). clumsiness starts to appear around 8-10 y/o. |
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Term
| what is motor system disease? |
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Definition
| a progressive degeneration of upper and or lower motor neurons in the spinal cord, brainstem, and motor cortex. the sensory system is spared. |
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Term
| what are the different classifications of motor system disease? |
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Definition
| pseudobulbar palsy (bulbar, UMN - normal nuclei in brainstem but the corticobulbar pathway get spastic paralysis of musculature), primary lateral sclerosis (spinal, UMN - pure spastic paralysis of limbs), progressive bulbar palsy (bulbar, LMN - atrophy of tongue, weakness of palate, difficulty swallowing ), and spinal muscular atrophy (spinal, LMN - degenerate anterior horn, atrophy and flaccidity of arms and legs, spare bulbar musculature). amyotrophic lateral sclerosis (ALS): combination of UMN and LMN of the bulbar and limb musculature (histologically: significant demyelination of lateral corticospinal tract and anterior horn cells). |
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Term
| what is the most common degenerative spinal cord disease (and overall myelopathy)? what is the clinical triad associated w/it? |
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Definition
| cervical spondylosis, which is due to degenerative arthritis of the cervical spine. clinical triad: neck pain, arm pain w/radicular symptoms (LMN), and signs in the upper extremities (LMN) |
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Term
| what are the nerve roots involved w/cervical spondylosis? which one is the most commonly involved? |
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Definition
| C6 thumb, C7 is 2/3 middle fingers, C8 last finger: most common is C7 nerve root involved. *pts w/a C7 radiculopathy present w/pain into their scapula and down their arm which is difficult to localize. they also may present w/a weak triceps or absent tricep reflex if the damage is significant. *pts w/C6 involvement may have a reduced bicep and brachioradialis reflex. *C8 is less common and does not have any reflex abnormalities, but they may have weakness of the intrinsic hand muscles, atrophy of the interossei muscles (scalloped) and hypothenar muscles (particularly on the abductor digiti minimi). |
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Term
| what is the morphology of the cervical spinal cord affected by spondylosis? |
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Definition
| the oval appearance is lost - get extradural disk protrusion |
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Term
| what can be a contributing factor to cervical spondylosis? |
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Definition
| congenital narrowing of the cervical canal. normal diameter is almost 2 cm, if it gets to 9-10 mm - can show compression at the level of the segment. |
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Term
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Definition
| cavitation of the central portion of the cord, which most frequently involves the cervical cord - but may extend into the brainstem. the concern is there may be an obstructive lesion upstream so look for spinal cord tumors at higher levels (generally don’t, often congenital), but need an MRI scan of the brain. |
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Term
| what is the pathogenesis of syringomyelia? tx? |
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Definition
| obstruction of the central canal, which can lead to problems with: the crossing fibers in the anterior commissure (where the spinothalamic tract crosses over) pts - can lose pain/temp sensation, the anterior horn cells - pts can experience segmental weakness and atrophy in the arms/hands (in a cape-like, upper body segmental pattern), and the lateral columns - less common, but pts can experience weakness and spasticity in their legs. tx: surgical shunt |
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