[Heat stroke: pathophysiology and pathogenesis]

The pathophysiology of heat stroke is not fully understood. Endotoxins and cytokines appear to play a major part in the central nervous system and in the peripheral tissues. Use of specific receptor blockers prior to heat exposure can diminish cerebral damage in animal experiments. The energy depletion model of Hubbard gives a possible explanation for the rhabdomyolysis observed in some heat stroke patients. Failure of the ATP dependent Na(+)-K+ pump is essential in this theory.

Calcium regulation by skeletal muscle membranes of horses with recurrent exertional rhabdomyolysis

OBJECTIVE

To determine whether an alteration in calcium regulation by skeletal muscle sarcoplasmic reticulum, similar to known defects that cause malignant hyperthermia (MH), could be identified in membrane vesicles isolated from the muscles of Thoroughbreds with recurrent exertional rhabdomyolysis (RER).

SAMPLE POPULATION

Muscle biopsy specimens from 6 Thoroughbreds with RER and 6 healthy (control) horses.

PROCEDURES

RER was diagnosed on the basis of a history of > 3 episodes of exertional rhabdomyolysis confirmed by increases in serum creatine kinase (CK) activity. Skeletal muscle membrane vesicles, prepared by differential centrifugation of muscle tissue homogenates obtained from the horses, were characterized for sarcoplasmic reticulum (SR) activities, including the Ca2+ release rate for the ryanodine receptor-Ca2+ release channel, [3H]ryanodine binding activities, and rate of SR Ca2+-ATPase activity and its activation by Ca2+.

RESULTS

Time course of SR Ca2+-induced Ca2+ release and [3H]ryanodine binding to the ryanodine receptor after incubation with varying concentrations of ryanodine, caffeine, and ionized calcium did not differ between muscle membranes obtained from control and RER horses. Furthermore, the maximal rate of SR Ca2+-ATPase activity and its affinity for Ca2+ did not differ between muscle membranes from control horses and horses with RER.

CONCLUSIONS AND CLINICAL RELEVANCE

Despite clinical and physiologic similarities between RER and MH, we concluded that RER in Thoroughbreds does not resemble the SR ryanodine receptor defect responsible for MH and may represent a novel defect in muscle excitation-contraction coupling, calcium regulation, or contractility.

Causes of poor performance of horses during training, racing, or showing: 348 cases (1992-1996)

OBJECTIVE

To determine results for horses undergoing a high-speed treadmill examination, including videoendoscopy of the pharynx and larynx before and during exercise, echocardiography before and after exercise, and electrocardiography before, during, and after exercise, because of poor performance.

DESIGN

Retrospective study.

ANIMALS

348 horses.

RESULTS

A definitive diagnosis was obtained for 256 (73.5%) horses. One hundred forty-eight horses had dynamic obstruction of the airway during exercise, 33 had clinically important cardiac arrhythmias alone, 22 had a combination of dynamic airway obstruction and clinically important cardiac arrhythmias, 19 had poor cardiac fractional shortening immediately after exercise, 10 had exertional rhabdomyolyis, 15 had clinically apparent lameness, and 9 had other disorders. Thirty-nine of the horses with dynamic obstruction of the airway during exercise had multiple airway abnormalities. Fifty-three horses also had subclinical myopathy

CONCLUSIONS AND CLINICAL RELEVANCE

Results suggest that a complete evaluation, including a high-speed treadmill examination, should be conducted in horses with poor performance, regardless or whether horses do or do not have a history of abnormal respiratory noises and particularly if the horses have grade-II or -III left laryngeal hemiplegia.

[Postural trauma and rhabdomyolosis causing acute renal failure]

Rhabdomyolysis (damage of the muscles of various origin) leads to the efflux of the intracellular fluids in the circulation. The common complication of this status is the renal failure. The early diagnosis and the proper treatment makes the fall of renal function reversible. That is why the possibility of the rhabdomyolysis must be consider. The case report describes the development of renal failure in young, previously healthy men, followed by trauma mechanism after drug and alcohol abuse.

Rhabdomyolysis associated with near-drowning

A variety of conditions can lead to rhabdomyolysis. Only a few cases of rhabdomyolysis resulting from near-drowning exist in the literature. We describe a victim of near-drowning who developed rhabdomyolysis and acute renal failure requiring dialysis. We review the existing literature on near-drowning-induced rhabdomyolysis and discuss the possible pathogenesis.

Abnormal regulation of muscle contraction in horses with recurrent exertional rhabdomyolysis

OBJECTIVE

To determine whether abnormal regulation of muscle contraction similar to that associated with malignant hyperthermia (MH) was evident in intact external intercostal muscle cells from Thoroughbreds with recurrent exertional rhabdomyolysis (RER).

ANIMALS

5 adult Thoroughbred horses with RER and 7 clinically normal adult Thoroughbred or mixed-breed horses.

PROCEDURES

Twitch time course variables and contracture responses to various concentrations of potassium, caffeine, and halothane were measured in small bundles of intact external intercostal muscle cells from clinically normal horses and horses with RER.

RESULTS

Threshold for significant contracture induced by potassium depolarization was lower for RER-affected muscles, compared with normal muscles, although the relationship between potassium concentration and membrane potential were not different. Thresholds for contracture induced by caffeine and halothane were also lower for RER-affected muscles, compared with normal muscles. Lower thresholds for caffeine- and halothane-induced contractures, as well as depolarization-elicited contractures, in RER-affected muscles suggest a defect in myoplasmic calcium regulation.

CONCLUSIONS AND CLINICAL RELEVANCE

Regulation of muscle contraction is abnormal in Thoroughbreds with RER. The specific defect may be attributable to abnormal intracellular calcium regulation. Knowledge of the specific defect involved in RER may lead to improved prevention and treatment of RER-affected horses.

In vitro contractile responses and contracture testing of skeletal muscle from Quarter Horses with exertional rhabdomyolysis

OBJECTIVE

To determine whether increased sensitivity to pharmacologic agents was a general property of equine exertional myopathies, including polysaccharide storage myopathy (PSSM) in Quarter Horses.

ANIMALS

5 adult Quarter Horses with exertional rhabdomyolysis and abnormal polysaccharide accumulation in skeletal muscle and 4 clinically normal adult Quarter or Quarter-type horses.

PROCEDURES

Twitch time course measurements and contracture responses to various concentrations of caffeine and halothane for small bundles of intact external intercostal muscle fibers were measured in all horses.

RESULTS

Caffeine contracture threshold of muscles from Quarter Horses with PSSM was not different from that of clinically normal horses (5 mM in both groups). Muscles from horses with PSSM and from clinically normal horses did not have contracture in response to up to 2% halothane.

CONCLUSIONS AND CLINICAL RELEVANCE

Results were in contrast to the increased sensitivity to caffeine and halothane for muscles from Thoroughbreds with recurrent exertional rhabdomyolysis (RER). Although clinical signs of muscular stiffness after exercise are similar between Quarter Horses with PSSM and Thoroughbreds with RER, these breeds appear to have 2 distinct myopathies with different pathophysiologic bases. Unlike RER in Thoroughbreds, PSSM in Quarter Horses does not appear to be accompanied by a defect in regulation of muscle contraction.

Marked elevation of serum creatine kinase associated with olanzapine therapy

OBJECTIVE

To report a case of marked elevation of serum creatine kinase (CK) associated with olanzapine therapy.

CASE SUMMARY

A 39-year-old white Jewish schizophrenic man treated with olanzapine developed an elevated serum CK concentration with a peak concentration of 4000 IU/L (normal < 230). No other diagnostic criteria for neuroleptic malignant syndrome (NMS) were present. On discontinuation of the drug, serum CK concentrations returned to normal within eight days.

DISCUSSION

Olanzapine, like other atypical antipsychotic drugs, may cause muscle injury with concomitant elevations of serum CK of muscle origin. We suggest that in patients treated with olanzapine, CK concentrations should be checked on initiation of therapy, within the first 48 hours, and weekly thereafter for at least one month. In addition, patients with clinical signs suggestive of NMS should be monitored more carefully. For those patients with a history of NMS, or even of isolated serum CK elevation during antipsychotic therapy, follow-up should be stricter.

CONCLUSIONS

Marked elevation of serum CK may be a possible complication of olanzapine therapy.

The management of shock and local injury in traumatic rhabdomyolysis

Rhabdomyolysis (literally "striped muscle dissolution") is a biological and clinical condition that takes to plasmatic release of myoglobin, muscle enzymes and electrolytes, relates to the lysis of stripped muscle fibers. Rhabdomyolysis presents the clinician with two distinct problems: local injury and the systemic effects directly related to that injury. Locally, muscle, vessel and nerve compression are the primary issues. Systemic concerns relate to depleted intravascular volume, electrolyte imbalances and renal injury from myoglobin. Preventing the systemic and renal complications of the crush syndrome requires very early and vigorous treatment to sustain the circulation, preferably started at the site of the catastrophe. During the extrication of an injured person from a collapsed building, wrecked automobile, or other site, isotonic saline solution should be infused at the rate of 1.5 liters per hour as soon one of the trapped person's limbs has been freed. Some authors suggest to do a preventive fasciotomy in any suspicious case of compartmental syndrome, when the patient has severe muscular pain of the muscular cavity, tense swelling, hypoesthesia or anesthesia of the muscular cavity, pain at the passive mobilization of the limb. On the other hand other surgeons suggest doing a fasciotomy only in selected group of patients. Therefore, the traumatic rhabdomyolysis has few diagnostically problems. On the other hand, their treatment is complex and must have a multidisciplinary approach. So the rhabdomyolysis actually remain a severe disease with high mortality caused principally by visceral lesions related to sepsis.

Bacterial sepsis-induced rhabdomyolysis

OBJECTIVE

To describe the syndrome of rhabdomyolysis during bacterial sepsis with regard to incidence, blood bacteriology and complications and to examine the association between hyperosmolal state and rhabdomyolysis, evaluating the relationship between plasma osmolality (Posm) and serum creatine phosphokinase (CPK) levels.

DESIGN

Prospective study including all patients admitted to the intensive care unit (ICU) for sepsis with positive blood culture and rhabdomyolysis over a 3-year period.

SETTING

Seven-bed medical/surgical ICU of a teaching hospital.

PATIENTS

35 patients (group 1) with bacterial sepsis-induced rhabdomyolysis (15 males, 20 females; mean age 71+/-13 years) and 122 (group 2) bacteraemic septic patients without rhabdomyolysis (49 males, 73 females; mean age 68+/-15) were studied. Patients with rhabdomyolysis were divided into gram(+) and gram(-) subgroups according to the blood culture growth.

RESULTS

From 491 patients recorded, 35 fulfilled the inclusion criteria for bacterial sepsis-induced rhabdomyolysis (7.1%). Gram-positive bacteria predominated in group 1 (69%), while gram-negative predominated (60%) in group 2. There was a correlation between CPK and Posm levels in the rhabdomyolysis Group (r = 0.52, R2 = 0.27, p = 0.003). There was a stronger correlation between these two variables (r = 0.67, R2 = 0.45, p = 0.001) in the gram(+).subgroup. Acute renal failure (68.5%) and electrolyte disorders such as hyperkalaemia (34%) and hypocalcaemia (48.5%) were the major complications in the rhabdomyolysis group. Sixteen (45.7%) patients in group 1 and 49 (40%) in group 2 died during their stay in the ICU from sepsis and multiple organ failure. Rhabdomyolysis was not considered a contributing factor to their death, as none of our patients died during or immediately after the syndrome.

CONCLUSION

Bacterial sepsis-induced rhabdomyolysis results from certain types of microorganisms, mainly gram-positive and to a lesser extent gram-negative. Hyperosmolality is a predisposing mechanism for rhabdomyolysis during bacteraemic sepsis from any type of bacterial microorganism.

Rhabdomyolysis

Dissolution of the skeletal muscle, resulting in extravasation of the intracellular toxic metabolites into the circulatory system, and the accompanying manifestations, constitutes the clinical syndrome of rhabdomyolysis. The most frequent complication of this syndrome is acute renal failure, and its most life threatening side effects are hyperkalemia and metabolic acidosis. Intracellular release of free iron from hemeprotein and the oxidant stress is the principle mechanism by which the proximal tubular cytotoxicity is produced. The potential pathogenic mechanisms and the strategies to prevent rhabdomyolysis induced acute renal failure are discussed in this article.

[Clinical case of the month. A case of acute rhabdomyolysis]

A 83 years old patient was admitted with a complex clinical picture including cutaneous rash, muscular pain, rhabdomyolysis and renal failure. The clinical picture suggests a dermatopolymyositis. Despite of high dose corticotherapy, the patient died on day 22. The anatomical examination shows a cholangiocarcinoma disseminated locally as well as in the lungs and bones.

Chest wall pain and possible rhabdomyolysis after chloropicrin exposure. A case series

Three cases are summarized in which persistent chest wall pain, as well as elevations of creatine phosphokinase (CK) levels, occurred after exposure to chloropicrin vapor in an agricultural chemicals facility. Both the severity of the symptoms and the degree of biochemical abnormality appeared to follow a dose-response relationship. Myoglobinuria, on the other hand, was not found. Elevation of CK after chloropicrin exposure has not previously been reported and may represent low-grade rhabdomyolysis. Workups performed after symptomatic chloropicrine exposure should include CK-level determination.

Haff disease associated with eating buffalo fish--United States, 1997

Haff disease is a syndrome of unexplained rhabdomyolysis following consumption of certain types of fish; it is caused by an unidentified toxin. Rhabdomyolysis is a clinical syndrome caused by injury to skeletal muscle that results in release of muscle cell contents into the circulation. In 1997, six cases of Haff disease were identified in the United States (four in California and two in Missouri) among persons who ate buffalo fish (Ictiobus cyprinellus), a bottom-feeding species found mostly in the Mississippi River or its tributaries. This report summarizes the investigation of these cases.

A causative role for redox cycling of myoglobin and its inhibition by alkalinization in the pathogenesis and treatment of rhabdomyolysis-induced renal failure

Muscle injury (rhabdomyolysis) and subsequent deposition of myoglobin in the kidney causes renal vasoconstriction and renal failure. We tested the hypothesis that myoglobin induces oxidant injury to the kidney and the formation of F2-isoprostanes, potent renal vasoconstrictors formed during lipid peroxidation. In low density lipoprotein (LDL), myoglobin induced a 30-fold increase in the formation of F2-isoprostanes by a mechanism involving redox cycling between ferric and ferryl forms of myoglobin. In an animal model of rhabdomyolysis, urinary excretion of F2-isoprostanes increased by 7.3-fold compared with controls. Administration of alkali, a treatment for rhabdomyolysis, improved renal function and significantly reduced the urinary excretion of F2-isoprostanes by approximately 80%. EPR and UV spectroscopy demonstrated that myoglobin was deposited in the kidneys as the redox competent ferric myoglobin and that it's concentration was not decreased by alkalinization. Kinetic studies demonstrated that the reactivity of ferryl myoglobin, which is responsible for inducing lipid peroxidation, is markedly attenuated at alkaline pH. This was further supported by demonstrating that myoglobin-induced oxidation of LDL was inhibited at alkaline pH. These data strongly support a causative role for oxidative injury in the renal failure of rhabdomyolysis and suggest that the protective effect of alkalinization may be attributed to inhibition of myoglobin-induced lipid peroxidation.

Rhabdomyolysis and acute renal failure in intensive care

The aetiology and pathophysiology of the complex clinical condition rhabdomyolysis are outlined here Rhabdomyolysis can be caused by a number of factors including excessive muscle activity, direct muscle injury, ischaemia and excesses of temperature Specific nursing care strategies, focusing on the pathophysiology of the condition, are proposed The priorities of care should centre on maintaining patient safety with monitoring of cardiovascular and respiratory systems and assessment of renal function

[Rhabdomyolysis in carnitine palmitoyltransferase II deficiency: developments in pathophysiology, diagnosis and therapy]

In hospitalized patients rhabdomyolysis is an important clinical entity, leading to myoglobinuria and acute renal failure in 8-25% of cases. When common causes of rhabdomyolysis, such as crush, trauma, infections, and drug abuse are excluded, inherited disorders of energy metabolism, in particular lipid metabolism, should be considered. Carnitine palmitoyltransferase (CPT) II deficiency is a common disorder of mitochondrial lipid oxidation. There are two distinct clinical forms: a severe and usually fatal infantile form and a benign classical muscular form. Usually, patients with CPT II deficiency present with episodic myoglobinuria, muscle cramps and weakness prompted by strenuous exercise or prolonged fasting. Liver and cardiac dysfunction are rarely seen and indicate severe disease. Most affected patients are males, although CPT II deficiency shows an autosomal recessive mode of inheritance. The human CPT II gene has been cloned, sequenced and localised to chromosome 1p32. Several mutations have been detected in the human gene which differ in the remaining enzyme activity and may explain the heterogeneity in the clinical picture of this disorder. Diagnosis is by muscle biopsy. Normally, light microscopy shows no pathological findings, and diagnosis must be established by biochemical and molecular methods. In our report on two typical cases we set out to promote knowledge of this disorder and discuss the diagnostic approach, which requires a specialised laboratory.

Electrolyte disturbances in foals with severe rhabdomyolysis

Marked electrolyte abnormalities characterized by profound hyperkalemia, hyponatremia, hypocalcemia, and hyperphosphatemia were noted in 4 neonatal foals with acute rhabdomyolysis and pigmenturia. In 2 foals, rhabdomyolysis developed 4-6 days after admission for dysmaturity, and in 2 foals, rhabdomyolysis was evident on presentation. Rhabdomyolysis was a consequence of selenium deficiency with or without vitamin E deficiency, possibly combined with increased oxidant stress due to sepsis or hypoxia and reperfusion injury after parturition. Foals gained from 7 to 15% of their initial body weight within 48 hours of developing rhabdomyolysis. Three of the foals developed cardiac arrhythmias characterized by spiked T waves and decreased-amplitude P waves. Postmortem examination of 2 foals revealed extensive myodegeneration and renal tubular nephrosis; renal cortical necrosis with myocardial necrosis was noted in 1 foal. Destruction of the major intracellular compartment (intracellular fluid [ICF]) through extensive myonecrosis combined, in some cases, with myoglobinuric renal insufficiency produced major fluid shifts and life-threatening electrolyte derangements. With the major ICF compartment disrupted, hyperkalemia was most effectively treated using mineralocorticoids, loop diuretics, and ion exchange resins to enhance elimination. In addition, i.v. calcium, glucose, insulin, and sodium bicarbonate were administered, which helped redistribute potassium to the ICF. Severe rhabdomyolysis should be included in the differential diagnoses of hyperkalemia, hyponatremia, hypocalcemia, and hyperphosphatemia in neonatal foals.

Marinesco Sjögren syndrome with rhabdomyolysis. A new subtype of the disease

Four children from two families with characteristics of Marinesco-Sjögren syndrome (congenital cataract, ataxia) are presented. All children had clinical and neurophysiological signs of a demyelinating polyneuropathy. Three of them developed acute rhabdomyolysis with marked weakness and CK levels of up to 40,000 U/I following a viral infection. In all children CK levels returned to normal within two weeks. Symptoms were recurrent in one of the children and resulted in a severe disability. In two other children recovery of motor function took about a month following the first attack. Metabolic disorders of the muscle were excluded by pathobiochemical examination of a muscle biopsy in one of the children. In conclusion, acute rhabdomyolysis can occur as a neuromuscular complication of Marinesco-Sjögren syndrome.

[Traumatic rhabdomyolysis. Physiopathology and treatment]

Crush syndrome or traumatic rhabdomyolysis constitutes the systemic changes seen after crush injury, i.e. the damages seen after a prolonged period of pressure on a muscle group. The pressure causes necrosis of muscle, and during revascularisation diffusion of calcium, sodium and water into the damaged muscle cells is seen, together with loss of potassium, phosphate, lactic acid, myoglobin and creatinine kinase. Untreated these changes can lead to: hyperkalaemia, acidosis, acute renal failure and hypovolaemic shock. Treatment of the systemic changes should be initiated immediately, aiming at a rapid correction of the extracellular volume and forced mannitol-alkaline diuresis. If renal failure develops, haemodialysis is started. The crush injuries are treated conservatively without fasciotomy, despite high or increasing intracompartmental pressure. The only indications for fasciotomy are lack of a distal pulse or open lesions. If fasciotomy is performed, radical removal of all necrotic muscle is essential.

[Serum creatine kinase MM isoforms and lactate dehydrogenase isoenzymes in patients with non-traumatic acute rhabdomyolysis]

We studied lactate-dehydrogenase (LD) isoenzymes and creatinekinase MM (CKMM) isoforms MM1, MM2 and MM3, in the serum of 18 patients with nontraumatic acute rhabdomyolysis, to test the utility of these markers in the diagnosis and disease evolution. The isoenzymes were separated by electrophoresis on agarose gel and were quantified with a densitometer. We studied the correlation between CKMM isoforms calculating the MM3/MM1 ratio, establishing the reference values from control group of 36 healthy adults. MM3 and MM3/MM1 ratio values were significantly increased in patients with rhabdomyolysis (p < 0.001) and progressively decreased coinciding with signs of getting better, showing 10 days after similar values of control group. LD4 and LD5 isoenzymes were significantly increased (p < 0.001) keeping elevated until 8-10 days when they showed a significant decrease compared with admission values (p < 0.05) but keeping elevated respect to control (p < 0.01).

Exertional rhabdomyolysis in an adolescent athlete

Exertional rhabdomyolysis has been previously reported in adult patients following such strenuous activities as military basic training, weight lifting, and marathon running. Exertional rhabdomyolysis in previously healthy pediatric athletes, however, is rarely encountered. The presentation of rhabdomyolysis is characterized by the classical triad of myalgias, muscle weakness, and darkened urine. This classic presentation, however, is not noted the majority of patients, especially early in the disease course when the patient may complain only of myalgias or weakness. Thus, the emergency physician must have a high index of suspicion for this entity based on the appropriate clinical setting. We report a classic case of exercise-induced rhabdomyolysis complicated by acute renal failure in a previously healthy adolescent athlete, whose initial presentation was nonspecific, prompting the diagnosis of overexertion.