Pathology of the Week – High-altitude illness

During the past few years I had the opportunity to learn mountaineering and ice/rock climbing from a few storied guides. I even got to climb one of Canada’s sixteen 10,000′-plus peaks. Although neither of us developed any form of high-altitude illness the trip prompted me to research the disease. High-altitude illness encompasses a group of acute pathologies which affect the bodies of individuals not accustomed to altitudes over 2,500m (8,202 feet) above sea level. These are acute mountain sickness (AMS), high-altitude cerebral oedema (HACE) and high-altitude pulmonary oedema (HAPE). AMS is far more common than HAPE and HACE with the latter two occurring in less than 0.1 to 4.0% of ascent cases. AMS equally affects both men & women as well as paediatric & adult patients. Strangely individuals over 50 seem to have a lower risk of developing AMS.  I will reference Basnyat & Murdoch, 2003 (free public access) as well as the Merck page on Altitude Sickness. See also BaseCamp MD.

Signs and Symptoms

Climbing Mt. Baldwin, summit: 10,682 ft

We in Canada actually contributed to the diagnosis of AMS!  The Lake Louise Consensus Group defines AMS as a new onset headache, in an unacclimatized person, who has recently travelled above 2500m as well as at least one of the following: fatigue, nausea, vomiting, loss of appetite, dizziness, and/or sleep disturbances. The symptoms typically begin 6 to 10 h after ascent and spontaneously subside after one to two days.

Pathology of the Week – Croup

medicalese: Scotch physician Dr. Francis Home first referred to croup in 1765; probably derived from the anglo-saxon word “kropan” (to cry).

Croup is a common and relatively benign condition in children. It is caused by an inflammation of the upper respiratory tract secondary to viral infection. It occurs almost exclusively in children, aged 6mo to 3y. The disease is more common in boys than girls (about 1.4:1). I will reference the Merck page on Croup, a few subscription-based articles (i.e. Bjornson et al., 2008) as well as a great free public access article by Malhotra & Krilov, 2001.

Signs and Symptoms

The hallmark symptoms of croup are a distinct “bark-like” cough and inspiratory stridor.

Pathology of the Week – Rhabdomyolysis

Medicalese: rhabdos – rod shaped; myo – related to muscle cells; lysis – break down of cells (greek for to separate). Short forms: rhabdo.

Rhabdomyolysis occurs when certain types of muscle cells (striated ones) break down allowing their contents to spill out into the bloodstream (the extracellular space). One of the contents of the cell is myoglobin which can damage a sensitive part of the kidneys called the tubules. The blood can handle some myoglobin floating around because it binds it to proteins which are too large to fit through the porous membranes of the glomeruli. When too much myoglobin is floating around in blood plasma not all of it becomes bound to protein and some passes into the sensitive renal tubules. A part of the myoglobin, heme, accumulates in the tubules and creates casts that cause tubule death and resultant acute renal failure. I will reference nephrologist Dr. Joel Topf’s 2009 case study as well as this 2000 Van Holder et al review (free public access). See also this physical therapist oriented video.

Pathology of the Week – Horner’s Syndrome

Horner’s Syndrome: Medicalese: named after Swiss ophthalmologist Johann Friedrich Horner in 1869.

This disorder is an interesting one to study as it involves some of the more complex cranial and autonomic nervous pathways. Horner’s syndrome is a grouping of four autonomic symptoms that arise from a loss of autonomic sympathetic nervous system input. These four symptoms are ocular ptosis, ocular miosis, facial anhydrosis and facial hyperaemia. All just big scary medicalese terms which I will detail below. I will reference the Merck Manual’s quick review, Jeff Mann MD’s guide, as well as an excellent neuroimaging article Lee et al, 2007 (article is free access).

Courtesy of OD Palace

Pathology of the Week – April 9th

Jervell and Lange-Nielsen syndrome. Medicalese: first described in 1957 by Anton Jervell and Fred Lange-Nielsen. Short forms: JLNS or J-LN syndrome

JLNS is the first in a weekly series of uncommon pathologies I will post. I first heard about this cardioauditory (two words not usually together) disorder from a February, 2010 Dr. Venkatesan blog post. Jervell and Lange-Nielsen syndrome (JLNS) is a genetic disorder that affects potassium channels in the heart and inner ear. This affects cellular repolarization and lengthens the cardiac action potential causing prolonged QT intervals and neural deafness. JLNS is the most severe variant of the congenital long QT disorders with over 90% of patients becoming symptomatic and 25% suffering sudden death. In a sample of 186 patients 50% had a cardiac event before age three and only 5% neared adulthood symptomless. See this Circulation article (free access) as well as this thorough review by Tranebjaerg et al.