Iatrogenic Flashcards
What is Cotton’s grading system for SGS?
- Grade 1: Less than so% laryngeal lumen obstruction.
<* Grade 2: 51-70% laryngeal lumen obstruction.
<* Grade 3: 71-99% laryngeal lumen obstruction.
<* Grade 4: Complete obstruction.
What are the three types of ORN?
- Type I occurs soon after radiation therapy
- Type II occurs long after radiation therapy and is induced by trauma
- Type III occurs long after radiation therapy and occurs spontaneously.
How much time must elapse before starting radiation after dental extractions?
10 days.
What is the incidence of ORN after radiation to the head and neck?
10-15%.
What percent of premature infants develop subglottic stenosis (SGS)?
4%.
At what doses can radiation retinopathy or optic neuropathy occurs?
50-55 Gy.
Cataracts can occur after how much radiation therapy?
6 Gy.
What problems are seen more commonly in patients with vocal cord paralysis due to a brainstem disorder?
Breathiness; pitch changes; chronic aspiration; and velopharyngeal insufficiency.
What are the ocular complications of radiation therapy?
Cataracts, radiation retinopathy, optic nerve injury, lacrimal gland damage, and ectropion/entropion.
What are other etiologies of SGS?
Congenital anomalies, increased infant activity, autoimmune mechanisms (antibodies to type II collagen, antineutrophil cytoplasmic antibodies), infection, GERD, caustic injury, and high tracheostomy.
What is the pathogenesis behind transient radiation myelopathy?
Demyelination of the posterior columns.
What accounts for vocal fold bowing observed with vocal fold paralysis?
Denervation atrophy of the thyroarytenoid muscle.
What are the treatment options for SGS?
Dilation, steroid injection, lathyrogenic agents, cryotherapy, laser therapy, anterior cricoid split, one-stage laryngotracheoplasty, autogenous cartilage grafts, four-quadrant cartilage division, end-to-end tracheal anastomosis, and flaps.
What are the risk factors for development of ORN?
Dose of radiation (>70 Gy), size, and extent of primary, postradiation dental extraction.
What effects does radiation therapy have on the skin?
Dryness secondary to damaged sebaceous and sweat glands, thinning of the epidermis, and telangiectasias.
What is the principle dose-limiting factor of radiation therapy?
Fibrosis of the subcutaneous tissue and muscle.
What is the most common cause of unilateral facial palsy in a newborn infant?
Forceps delivery.
What is the most common hormonal deficiency after radiation therapy for nasopharyngeal carcinoma?
Growth hormone deficiency.
What are the three most important factors leading to osteoradionecrosis (ORN)?
Hypovascularity, hypocellularity, and hypoxia (the “3Hs”).
If the paralyzed vocal cord is in the paramedian position, why is aspiration less likely?
Indicates that the superior laryngeal nerve is intact, and hence laryngeal sensation is intact.
What position will the vocal cord be in if the nerve is damaged at or above the nodose ganglion?
Lateral.
In patients with unilateral vocal cord paralysis, which side is most commonly involved?
Left.
What is the somnolence syndrome?
Lethargy, nausea, headache, cranial nerve palsies, and ataxia presenting 2-3 months after radiation therapy and lasting 2-4 weeks.
What clinical factors increase the risk of radiation injury?
Male gender, extremes of age, higher doses and fractions, and comorbidities.
Which bone in the head and neck is most commonly affected by ORN?
Mandible, as it has a relatively tenuous blood supply and is stress bearing.
What are the disadvantages of serial bouginage?
Multiple treatment applications over a prolonged period of time, lack of stabilization if cartilaginous destruction or instability has occurred, generally requires a tracheotomy.
What are the advantages of serial bouginage for the treatment of SGS?
Noninvasive growth may take care of the stenosis, avoids concerns regarding the potential for laryngeal growth inhibition with open procedures.
What position will the vocal cord be in if the nerve is damaged below the nodose ganglion?
Paramedian, due to innervation from the superior laryngeal nerve.
What is the biggest risk factor for acquired SGS?
Prolonged endotracheal intubation.
What are the two most common causes of vocal cord paralysis in adults?
Surgical trauma (#1) and lung cancer (#2).
What effects does radiation therapy have on the brain or spinal cord?
Transient radiation myelopathy, transverse myelitis.
Which cranial nerve is most commonly damaged by radiation therapy to the head and neck?
XII.
