Approach to Primary Amenorrhea

amenorrhea---primary

Primary Amenorrhea is defined as the absence of menses:

  • By age 13/14 without normal development of secondary sexual characteristics; OR,
  • By age 15/16, with normal secondary sexual characteristics.

In contrast, Secondary Amenorrhea refers to a loss of menses after it has already been established.

The causes of amenorrea are myriad, with an important one being pregnancy.

Causes of Amenorrhea
Hypothalamus Stress, malnutrition, exercise, lactation, immaturity, Kallmann syndrome
Pituitary Tumor, empty sella, apoplexy, hyperprolactinemia/prolactinoma
Ovaries Gonadal dysgenesis, premature ovarian failure, menopause, ovarian tumor, polycystic ovarian syndrome (PCOS), ovarian enzyme deficiency, chromosomal abnormalities (e.g., 45XO)
Uterus Intrauterine scarring, cervical agenesis, androgen insensitivity
Outflow Tract Imperforate hymen, transverse vaginal septum, cervical stenosis, Mullerian agenesis
Thyroid Hypo/hyperthyroidism
Pregnancy
Other Constitutional delay of puberty, hyperandrogenism, Cushing’s syndrome, medications

The most common pathologic causes of Primary Amenorrhea are:

  • Chromosomal abnormalities: 50%
  • Hypothalamic abnormalities: 20%
  • Mullerian agenesis: 5%
  • Pituitary abnormalities: 5%

Determining the etiology of Primary Amenorrhea depends on careful history-taking and a targeted physical exam. Key points to address in the history include:

  • Potential for pregnancy, current lactation
  • Develop of secondary sexual characteristics
    • On a side note, the general order of female sexual development is: breasts, pubic hair, growth spurt, menses; or, “boobs, pubes, grow, flow”
  • Lifestyle factors such as stress, nutrition, exercise, weight changes
  • Medication: THC, antipsychotics, or irradiation
  • Associated symptoms:
    • Hyperprolatinemia: galactorrhea
    • Hyperandrogenism: hair loss/excess, acne, voice change
    • CNS tumor: headaches, visual field deficits, polyuria/polydipsia
    • Family history: Does everyone have relatively late puberty?

In terms of physical exam:

  • Vitals, height, weight
  • Secondary sexual characteristics: breasts, pubic/axillary hair
  • Thyroid: exopthalmos, goiter, abnormal deep tendon reflexes
  • Hyperandrogenism: hirsuitism, acne, hair loss
  • Hypercortisolemia: striae, hyperpigmentation
  • Turner syndrome: webbed neck, low hair line, widely-spaced nipples, short stature
  • Pelvic exam: hymen, vaginal septum, ultrasound for uterine anatomy

Laboratory investigations can offer lots of insight:

  • βHCG: Gotta rule out this common reason first!
  • TSH, PRL: To test for hypo/hyperthyroidism and hyperprolactinemia.
  • LH, FHS: For practicality’s sake, these would probably be ordered at the same time as TSH, PRL.
  • +/- Androgens (testosterone, DHEAS, 17-alpha-hydroxyprogesterone): May indicate PCOS or androgen-secreting tumor, androhen insensitivity syndrome, or 5-alpha-reductase deficiency.
  • +/- Estradiol: These assays lack sensitivity, standardization, and only capture a single time point.

Since chromosomal abnormalities account for half of the pathologic cases of Primary Amenorrhea, karyotyping will be useful for patients who are found to have abnormal uterine anatomy on ultrasound or have elevated FSH, LH. Patients with an absent uterus may be worked-up for abnormal Mullerian development (46XX karyotype and normal female testosterone levels) versus a deficit in masculinization (i.e., androgen insensitivity syndrome, 5-alpha-reductase deficiency). There is a normal uterus, and LH and FSH are high, that means there is nothing feeding back to stop their release; karyotype may reveal Turner syndrome (45XO), while normal karyotype (46XX) may indicate Mullerian agenesis.

The over all treatment goals are to:

  • Treat underlying cause:
    • Lifestyle
    • Discontinue offending medications
    • Surgery
  • Preserve fertility
  • Reduce risk of complications (e.g., remove undescended tests in androgen insensitive patients to mitigate cancer risk).
  • Master-Hunter T, Heiman DL. 2006. Amenorrhea: evaluation and treatment; 73:1374.
  • The Practice Committee of the American Society for Reproductive Medicine. 2008. Current approach to amenorrhea. Fertility and Sterility;90:S219.
  • Welt CK, Barieri RL. Etiology, diagnosis, and treatment of primary amenorrhea. In: UpToDate (Eds: Snyder PJ, Crowley Jr WF, Kirkland JL). Accessed 2013.05.05.

Acute Limb Ischemia

acute limb ischemia

Acute limb ischemia is a sudden decrease in limb perfusion that can potentially threaten limb viability, in patients presenting within 2 weeks of symptom onset (it is considered chronic if more than 2 weeks have passed). The common causes of limb ischemia are:

  • Arterial embolism (80% of cases)
  • Thrombus (usually from site of atherosclerotic plaque)
  • Arterial trauma (e.g., after interventional catheterization procedures)

The symptoms can come on over a period of hours or days. It is important to recognize this condition, in order to improve the chance of limb preservation. Acute limb ischemia is characterized by the 6 P’s:

  • Pain
  • Paresthesia
  • Polar/Poikylothermia (affected extremity is cool on palpation)
  • Pallor
  • Paralysis
  • Pulselessness

If no pulse is palpable, then assessment of perfusion with a Doppler ultrasound is the next step. Note that acutely ischemic limbs may not always appear pale; the extremity may progress to a blue or mottled appearance as the ischemia continues. The most reliable symptoms are paresthesias, which will progress to complete loss of sensation, and paralysis, which may indicate the limb is no longer viable.

Once acute limb ischemia is identified, intravenous heparin is administered. Surgical or endovascular revascularization is the definitive treatment for acute limb ischemia, though these interventions should be performed within 6 hours of symptom onset to improve the probability of limb salvage.

  • Callum K and Bradbury A. 2000. ABC of arterial and venous disease: acute limb ischemia. British Medical Journal; 320:764.
  • Creager MA, Kaufman JA, and Conte MS. 2012. Acute limb ischemia. New England Journal of Medicine; 366:2198.
  • Mitchell ME, Mohler III ER, and Carpenter JP. Acute arterial occlusion of the lower extremities (acute limb ischemia). In: Uptodate (Eds: Clement DL, Hoekstra J, and Collins KA). Accessed 2013.08.24.

 

The “Safe Position” for the Hand

safe-position

People can be whiners sometimes. Their hand will be in a cast for some break and you’ll take it off and they will say, “my hand is stiiiiifffff

It’s not just them, the mechanics of their hand is working against them and if the cast wasn’t positioned properly, it can make matters much worse as far as stiffness is concerned. This is why when a hand or wrist is being casted or splinted, care is taken to put it in the position that will minimize stiffness.

The “safe position” is also known as the intrinsic plus position as it favours the weaker motions of MCP flexion and IP extension that are difficult to recover.

Wrist: The weight of your hand, gravity and resting muscle tension all work together to pull the wrist into flexion. When the wrist is flexed, there is more tension on the extrinsic extensor muscles and they pull the MCP joints into extension. The extrinsic flexors are stronger than the extensors and pull the IP joints into flexion. Taking the tension off the extensors limits their pull across the MCP joints.

The position of flexed wrist, extended MCP joints and flexed IP joints is known as intrinsic minus.

Metacarpal Phalangeal (MCP) Joint: These joints are a little funny due to the collateral ligaments on either side. These ligaments pass slightly above the axis of rotation of the joint, this means that when the joint is flexed, they’re at their longest and when the joint is extended, they’re at their shortest. This is due to the famed “CAM EFFECT.” Though often quoted, you have to wonder, what is a cam*? This website explains it well.

* This does not apply to all those people who remember basic mechanical principles or were trained in something more hands-on than neuroscience

Interphalangeal (IP) Joints: The ligaments around the IP joints are at maximum stretch when they are fully extended (aka 0 degrees)

Severity (Classification) of Burns

burn_depth

Burns are typically classified by their depth into (or through) the skin.

  1. 1st degree: just in the epidermis
    • Pink, hot, no blisters
    • Like a typical sunburn
  2. 2nd degree: into dermis, painful, wet
    • Superficial: unruptured blisters, hair & glands spared, erythematous (red) but blanch with pressure
    • Deep: ruptured blisters, hair often gone, can convert to a 3rd
  3. 3rd degree: through the dermis aka full thickness
    • Lack vascularization, dry, leathery, no sensation

Zones of a Burn

A burn isn’t a homogenous spot on the skin; more heat means more damage (who knew!)

  • 40 – 44 C: enzymes malfunction, protein denature
  • >44 C: damage occurs faster than the cell can handle
  • Damage keeps going after the heat source is removed
  1. Zone of Coagulation: The cells are dead and their proteins have denatured. Denatured proteins coagulate – think fried eggs. This is what forms the eschar of the burn.
  2. Zone of Stasis: The cells aren’t quite dead but the blood supply isn’t the best. If the circulation gets worse (usually due to vessel constriction and thrombosis) the cells in this area will die too. This is why it can take a couple days for a burn to “declare” itself.
  3. Zone of Hyperemia: “Hyperemia” means an increase in blood flow, in this case because of vasodilation. The cells in this area are alive and generally recover.

The image above shows a superficial 2nd degree burn. 

Vertebral Disc Prolapse (slipped disc)

A prolapsed (slipped) disc is when the squishy innards of the disc (nucleus pulposus) bulge out past the stiffer wall of the disc (annulus fibrosis). The problem is that sometimes when this happens, the bulge can impinge the spinal cord or the spinal nerve root. This could result in an anterior cord syndrome (remember this doodle) or it could just knock out the nerve root, resulting in a specific radiculopathy (check out this doodle for where to check for numbness and weakness).

The tricky thing to remember is that though, for example, the L3 root exits at L3, if the L3,4 disc herniates, it doesn’t hit the L3 root but the L4.

Slipped L3,4 disc = L4 nerve injury

The disc hits the nerve after it has branched off the spinal cord, but before it has exited the  vertebral canal.

Intracranial Hemorrhages

For the most part, bleeding in the brain (intracranial hemorrhage) is a pretty bad thing. Though like most things in medicine, there are varying degrees of badness, all with different mechanisms that help us sort of why we really wouldn’t want something to happen.

Intracranial hemorrhages are categorized into 5 subtypes, and are given obvious sounding names depending on where the bleed is in the brain and in relation to the layers of the meninges.

  1. Epidural (above the dura, right under the skull)
  2. Subdural (below the dura, above the arachnoid)
  3. Subarachnoid (below the arachnoid, above the brain)
  4. Intraventricular (in the ventricles)
  5. Intraparenchymal (in the meat* of brain)

* The brain is not meaty, “parenchyma” means the functional part of the organ

The poor pia mater did not get any hemorrhage named after it, but if you want you can think of intraparenchymal as “subpial” just so it doesn’t feel left out.

Telling them apart

The most confusing thing, and thing that likes to get asked the most on exams, is the difference between epidural and subdural hematomas.

Epidural Subdural Subarachnoid
Above the dura Below the dura Below the arachnoid
Respects suture lines Doesn’t respect suture lines No respect for anything
High force trauma Low force trauma Aneurysm rupture or high force trauma
Arterial blood (commonly the middle meningeal artery) Venous (from venous plexus) Arterial from the circle of Willis
Lentiform (lens-shaped) or biconcave on CT Cresent (banana-shaped) on CT Lining surface, going into fissures and sulci and sella (death-star)
Acute presentation May be insidious (worsening headache over days) Acute presentation (thunderclap headache)

The reason intraventricular and intraparenchymal aren’t included in the table as they each have a bunch of causes, but for both of them trauma is a potential cause as well as hypertension and stroke. It’s good to remember that premature infants are at a much higher risk of intraventricular hemorrhages.

Blood on CTs

  • New blood: bright white
  • 1-2 weeks: isodense
  • Old blood (2-3 weeks): dark grey

Shock

BUY THIS AS A STUDY CARD

Shock is “a syndrome resulting from failure of the cardiovascular system to maintain adequate tissue perfusion.”

Weil-Shubin Classification of Shock

  1. Cardiogenic –  Poor cardiac function reduces forward blood flow.
  2. Hypovolemic – Loss of intravascular volume caused by: hemorrhage, dehydration, third space loss, vomiting, diarrhea.
  3. Obstructive – Impair cardiac filling due to external restriction. Caused by cardiac tamponade, tension pneumothorax, pulmonary embolus.
  4. Distributive – Primarily characterized by loss of peripheral vascular tone. Caused by septic, anaphylactic, adrenal insufficiency, neurogenic, liver failure.

Adrenergic Receptors

  • α1: Vasoconstriction
  • α2: Inhibits norepinephrine release, decreases BP, sedative effects
  • β1: Positive inoptrope (increases cardiac contractility and stroke volume)
  • β2: Vasodilation, broncodilation

Vasoactive Drugs

Epinephrine

  • Effects: Causes vasoconstriction and increases cardiac output. Inotrope effect predominates at low doses (< 4.0 mcg/min).
  • Disadvantages: Associated with lactic acidosis, hyperglycemia, pulmonary hypertension, tachyarrythmias, and compromised hepatosplanchnic perfusion.
  • Use: First-line agent for cardiac arrest and anaphylaxis. Second-line agent for vasopressor and inotrope effects, when other agents have failed.

Norepinephrine

  • Effects: Potent vasoconstrictor. Causes a minor increase in stroke volume and cardiac output.
  • Disadvantages: May decrease renal blood flow and increase myocardial oxygen demand. Extravasation at site of intravenous administration may lead to tissue necrosis.
  • Use: First line therapy for maintenance of blood pressure.

Ephedrine

  • Effects: Increases heart rate, cardiac output. Bronchodilator. Some anti-emetic effects. Longer duration than epinephrine. Has indirect actions on adrenergic system.
  • Disadvantages: Epedrine losses effect with subsequent doses since part of its effect is indirect, by icreasing NE release, which becomes depleted
  • Use: Common vasopressor during anesthesia, but only a temporizing agent in acute shock.

Dopamine

  • Effects are dose-dependent:
    • < 5 mcg/kg/min – Acts at dopamine receptors only, with mild inotrope effect. Vasodilatory effects purported to improve perfusion through renal and mesenteric vessels; however, there is no clear clinical benefit of dopamine on organ function.
    • 5-10 mcg/kg/min – Predominantly β1 adrenergic effects. Increases cardiac contractility and heart rate.
    • >10 mcg/kg/min – Predominately α1 effects, causing arterial vasoconstriction and increased blood pressure. Overall decrease in renal and splanchnic blood flow at this dose.
  • Disadvantages: Has a high propensity for tachycardia and dysrythmias. Potential for prolactin suppression and immunosuppression.
  • Use: First line vasopressor for shock, but may be associated with more adverse outcomes than norepinephrine.

Dobutamine

  • Effects: Racemic mixture. where the L-isomer acts at α1/β1 receptors and D-isomer acts at β1/β2 receptors. Increases cardiac output and decreases systemic/pulmonary cascular resistance. Can increase splanchnic blood flow and decrease endogenous glucose production.
  • Disadvantages: May cause mismatch in myocardial oxygen delivery and requirement. Vasodilation undesirable in septic patients.
  • Use: A ‘gold standard‘ inotropic agent in cardiogenic shock with low output and increased afterload. In sepsis, vasodilatory effects should be counteracted by co-administration with norepinephrine.

Dopexamine

  • Effects: Acts at β2 and dopamine receptors. Causes vasodilation and decreased afterload. Has some positive inotrope effect. Bronchodilatory. Unlike dopamine, dopexamine is not associated with pituitary suppression.
  • Disadvantages: Not widely accepted in practice.
  • Use: Like dobutamine, useful for cardiogenic shock with decreased output and high afterload.

Phenylephrine

  • Effects: Classic selective α1 agonist, causing vasoconstriction. Rapid onset and short duration.
  • Disadvantages: Can reduce hepatosplanchnic perfusion. May cause significant reflex bradycardia.
  • Use: Generally considered a temporary vasopressor until more definitive therapy is begun. Useful for vasdilated patients with adequate cardiac output, for whom other vasopressors present risk of tachyarrhythmias.

Dexmedetomidine/Clonidine

  • Effects: Arousable sedation with preserved respiratory drive. Improved tissue perfusion and renal function. General sympathetic inhibition.
  • Disadvantages: Bradycardia and hypotension.
  • Use: Not used in acute shock setting, but may be useful in later critical care setting.

Vasopressin (not actually an adrenergic drug)

  • Effects: Acts on V1 receptors to cause vasoconstriction. Increases vasculature response to catecholamines.
  • Disadvantages: May cause tachycardia and tachyarrythmias. Excessive vasoconstriction can impair oxygen delivery and and cause limb ischemia.
  • Use: May be used to augment norepinephrine or other agents. Not typically used alone.

Innervation of the lower leg

The lower leg (and especially the foot) have a pretty fancy pattern of skin innervation by the terminal branches. For example, the skin of the foot is innervated by 7 separate nerves:

  1. Superficial peroneal nerve
  2. Deep peroneal nerve
  3. Sural nerve
  4. Saphenous nerve
  5. Calcaneal branch of the tibial nerve
  6. Medial branch of plantar nerve
  7. Lateral branch of plantar nerve

Also good to keep in mind that the anterior compartment is innervated by the deep peroneal nerve, the lateral compartment by the superficial peroneal nerve and the posterior compartment by the tibial nerve.

Extensor Compartments and Extensor Zones of the Hand

Extensor Compartments

There are a whole lot of wrist/finger extensors trying to fit in the wrist and anatomically these are divided into 6 compartments.

  1. First compartmentit’s this that is affected in de Quervain tenosynovitis
    • APL (abductor pollicis longus): attaches to 1st MC
    • EPB (extensor pollicis brevis): attaches to base of proximal phalanx
  2. Second compartment
    • ECRB (extensor carpi radialis brevis): attaches to 3rd MC
    • ECRL (extensor carpis radialis longus): attaches to 2nd MC
  3. Third compartment
    • EPL (extensor pollicis longus): passes around Lister’s tubercle of radius and inserts on distal phalanx of thumb (extends thumb IPJ)
  4. Fourth compartment – the posterior interosseus nerve lies on the floor of this compartment
    • EDC (extensor digitorum communis): no direct attachment to phalanx, attaches to the extensor expansions
    • EIP (extensor indicis proprius): lies ulnar to 1st EDC tendon)
  5. Fifth compartment
    • EDM (extensor digiti minimi): attaches to extensor expansion of little finger
  6. Sixth compartment
    • ECU (extensor carpi ulnaris): attaches to base of 5th MC

Extensor Zones

  • Zone I: over the DIP (this is where mallet finger injuries occur)
  • Zone II: middle phalanx
  • Zone III: over the PIP
  • Zone IV: proximal phalanx
  • Zone V: over the MCP
  • Zone VI: dorsum of hand/metacarpals
  • Zone VII: over the extensor retinaculum/carpals
  • Zone VIII: proximal wrist

Juncturae Tendinum

  • This is the connections of fascia between the EDC tendons and why you can’t stick your ring finger up alone, as it prevents independent movement.
  • It can also lead to confusion about whether an extensor tendon has been cut as the juncture tendinum transmits MCP joint extension even if a tendon is cut (as long as it’s cut distal to the JT)
  • But it’s also helpful as it prevents the cut tendon from retracting up into the forearm

Thumb (1st metacarpal) Fractures

Thumb fractures, and by this I mean 1st metacarpal fractures, have a couple of distinct patterns that are different from the other metacarpals.

Type I: Bennett Fracture

  • This fracture is intra-articular on the ulnar side of the first metacarpal, basically making a little triangle
  • It’s that little ulnar fragment that stays attached to the trapezium by the virtue of the volar ligament
  • The distal aspect of the metacarpal gets supinated and dislocated radially no thanks to the adductor pollicis
  • The fragment gets pulled proximally by the abductor pollicis brevis and abductor pollicis longus

Type II: Rolando Fracture

  • You can think of this fracture as a really busted up Bennett’s (comminuted). It is also intra-articular and usually makes a Y or T shape
  • These kind generally heal poorly but thankfully are fairly rare

Type III: Other extra-articular fractures

  • This is basically any other 1st metacarpal fracture (all the extra-articular ones)
  • They are the most common, but don’t have fancy names, just lame ones like “transverse“, “oblique“, etc.

Type IV

  • These really only exist in paediatrics and involve the proximal physis (growth plate)

Treatment: it’s best to treat Bennett and Rolando Fractures with thumb spica splints and then refer them to your friendly neighbourhood plastic surgeon or orthopaedic surgeon as they might need pinning or an open reduction.

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