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.

 

BOOTS: Predictors of Difficult Bag Mask Ventilation

boots

Bag mask ventilation (BMV) is an important means of ventilating and oxygenating a patient unable to protect their airway, or in respiratory depression. BMV can be useful as a primary airway management modality in a prehospital setting, and it is also a useful rescue maneuver for cases of  difficult endotracheal intubation.

The following patient features, however, will make BMV difficult; this can be remembered with the helpful mnemonic BOOTS:

  • Beard
  • Obese
  • Old Age
  • Toothless
  • Snores

Essentially, BMV can be complicated any condition that impairs formation of an effective mask seal.  Beards can make establishing an adequate seal difficult, as can any disruption of normal facial anatomy (no teeth, facial fractures, excess facial tissue). Individuals aged over 55 years old are considered to be higher risk for BMV, in part because of decreased upper airway muscle tone. Patients should be screened for obstructive sleep apnea before an elective surgery; also, note that conditions increasing airway resistance (e.g., severe asthma) or decreasing pulmonary compliance (e.g., pulmonary edema) can make ventilation challenging.

  • Hung O and Murphy MF (Eds). 2008. Management of the difficult and failed airway. McGraw-Hill.
  • Kovacs G and Law JA (Eds). 2011. Airway management in emergencies. People’s Medical Publishing House-USA.

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.

Lateral Spinothalamic Pathway

The Lateral Spinothalamic Pathway is an ascending spinal tract, carrying sensory information to the brain. It is typically depicted as a chain of three neurons: first-, second-, and third-order neurons.

This pathway mediates sensation of pain and temperature.

The first-order neurons in the pathway are located in the dorsal root ganglia at all spinal levels. Their axons ascend the tract of Lissauer, and synapse with second-order neurons.

The second-order neurons are located in the dorsal horn, and their axons immediately decussate via the ventral white commissure. These axons ascend the lateral funiculus and project to the ventral posterolateral (VPL) nucleus of the thalamus.

Some collaterals are sent to areas involved in arousal, namely the midbrain reticular formation, and the intralaminar nuclei of the thalamus (which then project to the caudatoputamen, and frontal and parietal cortex).

The third-order VPL neurons send axons through the posterior limb of the internal capsule to the somatosensory cortex (areas 3, 1, 2).

Lesions to the Lateral Spinothalamic Pathway

Spinal cord lesions affecting the Lateral Spinothalamic pathway result in contralateral sensory deficits below the lesion, because the pathway immediately decussates at the second-order neuron level.

Ventral Spinothalamic Pathway

There is also a Ventral Spinothalamic Pathway, that carries crude touch sensation. It is organized very similarly to the Lateral Spinothalamic pathway; however, it is less clinically-emphasized since the Dorsal Column Medial Lemniscus pathway is more important for touch sensation. If the Ventral Spinothalamic pathway is lesioned, touch sensation will only be minimally affected, as long as the dorsal column remains intact.

Dorsal Column Medial Lemniscus Pathway

Guest post!

The Medial Lemniscus-Dorsal Column pathway is an ascending spinal tract, carrying sensory information to the brain. It is typically depicted as a chain of three neurons: first-, second-, and third-order neurons.

This pathway mediates:

  • Conscious proprioception (most clinically relevant)
  • Sensation of tactile discrimination
  • Vibration sense
  • Form recognition

First order neurons

The first-order neurons in the pathway are located in the dorsal root ganglia at all spinal levels, giving rise to the fasciculus gracilis tract in the lower extremity and the fasciculus cuneatus tract in the upper extremity. The axons comprising these funiculi ascend ipsilaterally to the medulla, where they synapse with the second-order neurons.

Second order neurons

The second-order neurons are located in the cadual medulla, and their cell bodies form the gracile and cuneate nuclei. Their axons, referred to as internal arcuate fibers, decussate to form the medial lemniscus, which ascends the contralateral brainstem to project to the ventral posterolateral (VPL) nucleus of the thalamus.

Third order neurons

The third-order VPL neurons send axons through the posterior limb of the internal capsule to the somatosensory cortex (areas 3, 1, 2)

Spinal cord lesions affecting the dorsal column (e.g., vitamin B12 neuropathy, tabes dorsalis) result in ipsilateral sensory deficits below the lesion, because the pathway does not decussate until it is at the level of the medulla.

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