Absite killer Plus Basic Science



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Esophagus


No serosa; mucosa is strongest layer (in small bowel, submucosa is strongest)

Central input initiates swallow which elicits primary peristalsis, distention then elicits secondary peristalsis. Sphincters are contracted at rest. Normal LES tone = 15-25 mmHg (length 4cm)

Swallowing order of events: soft palate closes nasopharynx, larynx up, larynx closes, UES relaxes, pharyngeal contraction

Zencker's diverticulum: occurs in Killian's triangle, due to incr pressure (pulsion tic), need myotomy and diverticulectomy/pexy. Approach via left cervical incision

Paraesophageal hernia: always operate since risk of incarceration, strangulation (Every Year)

Diffuse esophageal spasm: medical treatment (Ca channel blockers)

Esophageal rupture (Boerhaave's) key to survival is early Dx (85% dead if > 36 hours)

Achalasia: decr ganglion cells in Auerbach's plexus, absence of peristalsis and esophageal dilation. Bird's beak on Ba swallow; manometry shows no peristalsis, high LES pressures/failure to relax. Rx: laparoscopic or thoracoscopic Heller myotomy

Barrett's esophagus: metaplasia from squamous to columnar cells. 1-2% get adenocarcinoma (30-100 x risk) P53 associated (tumor suppresor gene)

Achalasia and chemical ingestion also incr risk of esophageal CA

AdenoCA now #1 esophageal cancer over squamous (also true for lung CA)

R gastroepiploic artery is main supply to stomach when used to replace esophagus

Leiomyoma: if symptomatic or > 5cm excise by enucleation via thoracotomy (R if middle, L if lower esophagus). Do not biopsy on EGD.

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Head and Neck


Anterior to posterior: subclavian vein, phrenic nerve, anterior scalene, subclavian artery

Parotitis: staph. Seen in elderly, dehydrated, Rx abx; drainage if abscess/not improving

Painless mass on roof of mouth: Torus (bony exostosis, midline of palate)

Erythroplakia is worse (pre-malignant) than leukoplakia. Retinoids can reverse leukoplakia and reduce chance of 2nd head and neck malignancy

Head and Neck SCCa: Stage I, II (up to 4cm, no nodes) Rx with single modality (surgery or RT); III, IV get combined modality

Nasopharyngeal SCCa present late (50% as neck mass), drain to posterior neck nodes, a/w EBV

Glottic CA: if cords not fixed, then RT; if fixed, need surgery and RT

Lip CA (99% epidermoid carcinoma): lower > upper due to sun exposure; resect, primary closure if < 1/2 of lip, otherwise flaps. Radical neck dissection if node +

Tongue CA: usually need surgery and XRT. Incr in plummer vinson (dysphagia, spoon fingers, anemia)

Larger salivary glands (parotid) = more likely for tumor to be benign

Mucoepidermoid Carcinoma: #1 malignant salivary tumor overall

Adenoid Cystic Carcinmoa: #1 malignant salivery tymor of the submandibular/mino glands

Pleomorphic adenoma = mixed parotid tumor = #1 benign tumor, do not enucleate, needs superficial parotidectomy (spare CN7); if malignant, take whole parotid w/CN7; If high grade (anaplastic), need radical neck dissection

Warthin's tumor (adenolymphoma) #2 benign salivary tumor. 10% bilateral. 70% of bilateral parotid tumors are Warthin's tumor. Rx: superfiical parotidectomy.

Radical neck dissection takes CNXII, SCM, IJ, submandibular gland. Most morbid = CN XII

Juvenile Nasopharyngeal Angifirboma: benign, in teen males, present w/obstruction, epistaxis. Rx embolize (internal maxillary a), then extirpate

Frey's syndrome: injury of auriculotemporal nerve; gustatory sweating (crossed sweat/salivary fibers)

Massive bleeding from trach is from innominate artery (tracheo-innominate fistula) Present w/small heraldic bleed. Avoid by making tracheostomy no lower than 3rd tracheal ring.

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Hepatobiliary


R hepatic artery off of SMA in 17% (Every Year)
L hepatic artery off of L gastric artery in 10%

Kupffer cells: clear portal blood immunosurveillance

Portal triad: portal vein posterior to CBD (on R) and hepatic artery (on L)

Hepatorenal syndrome: see low urinary Na

Cholangitis: jaundice, RUQ tenderness, fever, hypotension, change in mental status
Needs immediate IV abx, fluid resuscitation and emergent drainage of CBD (Every Year)

Retained CBD stone identified on T-tube cholangiogram 6 wks postop best managed by radiology stone retrieval

Benign biliary stricture: #1 cause is iatrogenic (lap chole)

Gallbladder adenocarcinoma: 90% have stones. Cholecystectomy adquate if confined to mucosa. If grossly visible tumor, do regional lymphadenectomy, wedge segment V, skeletonize portal triad.

Porcelain gallbladder = 30-65% risk of cancer. Cholecystectomy indicated.

Hematobilia triad = GI bleed, jaundice, RUQ pain. workup (and rx) with arteriogram

Gallbladder concentrates bile by active absorption of Na, Cl (H2O then follows)

Hepatic adenoma: 10% rupture/bleed; have malignant potential; 'cold' on liver scan. Hepatic adenoma is an indication for resection. (Every Year)

Hepatic hemangioma: do nothing unless giant or symptomatic/consumptive. Kasaback Merritt syndrome: consuptive coagulopathy or CHF due to hemangioma.

Amebic abscess (anchovy paste) Rx metronidazole, not surgical

Hydatid = Echinococcal cyst: +Casoni skin test, +indirect hemagglutination; resect (pericystectomy)

Hepatocellular CA is #1 CA worldwide. May have high alpha-FP.


Chronic Hep B and C is #1 cause; also assoc w/any cirrhosis (EtOH, hemochromatosis, primary biliary cirrhosis, alpha-1 antitrypsin deficiency), clonorchis sinensis (flukes), aflatoxin, Fibrolamellar variant has better Px.

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Neurosurgery


Peripheral nerve injuries:
Neuropraxis = focal demyelination, improves
Axonotmesis = loss of axon continuity (nerve and sheath intact). Regenration 1 mm/day.
Neurotmesis = loss of nerve continuity, surgery required for nerve recovery

ADH produced when high osmolarity is sensed at supraoptic nucleus of hypothalamus


Causes incr free H2O absorption at the distal tubules and collecting ducts
Alcohol and head injury inhibit ADH release = Diabetes Insipidus
DI = high urine output, low urine SG, high serum osmolarity/Na
May also see SIADH with CHI = oliguric, high urine osmolarity, low serum osmo/Na (Every Year)

AVM's: congenital, bleed age 40-60; aneurysms younger (age 20-59), are a/w HTN

Most adult brain tumors are malignant, spinal cord tumors are 60% benign (extradural likely malignant/met)

Acoustic neuroma: CN8 at the cerebello-pontine angle (cps)

13% of patients with head injury have a spinal injury

Subdural hematoma: crescent shape, conforms to brain; 50% mortality

Epidural hematoma: lens shape, goes into brain, 10% mortality, middle meningeal artery, 'lucid interval'

Cerebral perfusion pressure = CPP = MAP - ICP, want to keep ~70 (Every Year)

Cushing's triad with incr ICP: HTN, bradycardia, Kussmaul respirations (slow, irregular)

GCS Motor: 6 commands, 5 localizes, 4 withdraw pain, 3 flexion pain (decorticate), 2 extension pain, 1 none


GCS Verbal: 5 oriented, 4 confused, 3 inappropriate, 2 incomprehensible, 1 none
GCS Eyes: 4 spontaneous, 3 to command, 2 to pain, 1 none (Every Year)

GCS 8 or less: ICP monitor indicated; 10 or less intubation indicated; GCS 5 ~ 50% mortality

Cord injury above T5 can cause spinal shock; Rx with fluids, may need alpha-agonist. Recognize by hypotension with bradycardia, warm perfused extremities (vasodilated).

Anterior spinal artery syndrome: lose bilateral motor, pain and temp; keep position sense, light touch

Brown Sequard: spinal cord transected 1/2 way; lost ipsilateral motor, contralateral pain and temp

Central Cord Syndrome: bilateral loss of upper extremity motor, pain, temp; legs relatively spared. usually due to hyperextended c-spine injury

Skull fx: to OR if open fx or if depressed (to ~ thickness of skull or more)

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