Thyroid hypokalemic periodic paralysis

An unusual presentation of thyrotoxicosis resulting in hypokalemic periodic paralysis is reported here. The patients with this disorder have very low serum potassium levels during the active phase of the disease. Very often, several months pass before the diagnosis is made. Once recognized and the thyrotoxicosis is treated, the patient does well.     

Hypokalemic periodic paralysis: new advances

Retrovirus particles contain a small, basic protein, the nucleocapsid (NC) protein, that possesses 'nucleic acid chaperone' activity--that is, the NC protein can catalyze the rearrangement of a nucleic acid molecule into the conformation that has the maximal number of base pairs. The molecular mechanism that underlies this effect is not understood. Because the chaperone activity is apparently crucial during the infectious process, NC is a potential target for antiviral therapy.     

Andersen''s syndrome: a distinct periodic paralysis

PURPOSE: To develop a stable, transluminally created abdominal aortic aneurysm (AAA) within a live animal model. MATERIALS AND METHODS: Eight mongrel dogs were utilized to evaluate a new, catheter-based technique for the creation of an AAA. With use of a standard angioplasty balloon and a balloon-expandable intravascular metallic stent, the infrarenal abdominal aorta was overdilated to twice its measured diameter into a fusiform shape AAA in eight dogs. At 30 days, aortography was performed, the dogs were killed, and the aorta was resected and evaluated for histopathology. RESULTS: Seven of the eight dogs that underwent transluminal AAA creation survived the initial procedure. A stable, fusiform AAA was successfully created in these seven dogs. At 30 days, repeat angiography and histologic examination confirmed that the seven AAAs were still twice the diameter of the normal aorta (a four-fold increase in luminal area), that the branch arteries remained patent, and that the lumen was endothelialized. One of the eight dogs was killed 9 hours after the procedure because of inability to awaken from anesthesia. Gross and histopathologic results in this one dog also demonstrated an intact aorta containing an AAA. CONCLUSIONS: A stable, infrarenal AAA model can be successfully created in the canine species with use of standard catheter-based techniques and equipment. This model can be used to test emerging endovascular treatments of AAA.     

The effect of acidosis in hypokalemic periodic paralysis

Metabolic acidosis was produced in two patients with hypokalemic periodic paralysis by the administration of ammonium chloride over a period of three days. The challenging test of glucose and insulin produced a substantially smaller reduction of both serum potassium concentration and muscle strength than when the patients were tested in normal acid-base balance. The findings agree with earlier work on acetazolamide, suggesting that metabolic acidosis provides protection against episodes of muscle weakness in periodic paralysis.     

Familial hypokalemic periodic paralysis. Clinical, diagnostic and therapeutic aspects

A model of induced lactation was modified to examine the effects of bovine prolactin (bPRL) and bovine placental lactogen (bPL) on mammary growth and differentiation. Thirty-two peripubertal, non-pregnant Holstein heifers were given daily s.c. injections of oestradiol (0.05 mg/kg) and progesterone (0.25 mg/kg) for 7 days to initiate mammary growth. Treatment with bromocriptine (40 mg/3 days) reduced serum PRL concentrations to approximately 25% of pretreatment levels, for the duration of the study. On the day following the last steroid injection, groups of eight heifers were given twice daily s.c. injections of either saline (negative control), recombinant bPRL (rbPRL; 80 mg/day) or recombinant bPL (rbPL; 80 and 160 mg/day) for 7 days. At the end of this period (day 15), growth and differentiation of the mammary glands were assessed. Treatment with rbPL increased total mammary DNA above control value by 50 and 60% for the 80 and 160 mg/day doses respectively. However, total DNA was not different for the control and rbPRL-treated groups. The blood serum concentration of alpha-lactalbumin was measured daily throughout the study and used as an index of mammary differentiation. Both rbPRL and rbPL stimulated mammary differentiation (i.e. induction of milk synthesis), although rbPRL appeared to be more potent than rbPL. These results indicate that rbPL is lactogenic in vivo and strongly suggest that bPL is a mammary mitogen.     

A thyrotropin-secreting pituitary adenoma as a cause of thyrotoxic periodic paralysis

We describe a patient with thyrotoxic periodic paralysis (TPP) caused by a thyrotropin-secreting pituitary adenoma. The diagnosis TPP was based on the combination of episodes of reversible hypokalaemic paralysis, hyperthyroidism and electrophysiological findings. A thyrotropin-secreting pituitary adenoma was diagnosed on the basis of endocrinological function tests and MRI of the pituitary gland. Before transsphenoidal resection of the adenoma, treatment with octreotide restored euthyroidism both clinically and biochemically. Immunocytochemistry of the pituitary adenoma was positive for TSH exclusively. Incubation with octreotide or quinagolide induced decreased TSH and alpha-subunit production by the cultured adenoma cells, in agreement with the pre-operative in vivo data. This paper is the first to describe in vivo and in vitro characteristics of a thyrotropin-secreting pituitary adenoma in a patient presenting with periodic paralysis.     

Improvement of the exercise test after therapy in thyrotoxic periodic paralysis

The diagnosis of periodic paralysis (PP) can be aided by demonstrating a decrease in compound motor action potential (CMAP) amplitude after several minutes of exercise. We report a case of secondary hypokalemic PP due to thyrotoxicosis in which the decrease in the CMAP amplitude after exercise dramatically improved after treatment, when a euthyroid state was achieved. The exercise test is a useful electrophysiologic means of monitoring the neuromuscular status of patients with thyrotoxic periodic paralysis prior to, and after treatment of the thyrotoxicosis.     

Functional consequences of a Na+ channel mutation causing hyperkalemic periodic paralysis

Hyperkalemic periodic paralysis (HYPP), one of several inheritable myotonic diseases, results from genetic defects in the human skeletal muscle Na+ channel. In some pedigrees, HYPP is correlated with a single base pair substitution resulting in a Met replacing Thr704 in the fifth transmembrane segment of the second domain. This region is totally conserved between the human and rat channels. We have introduced the human mutation into the corresponding region of the rat muscle Na+ channel cDNA and expressed it in human embryonic kidney 293 cells. Patch-clamp recordings show that this mutation shifts the voltage dependence of activation by 10-15 mV in the negative direction. The shift results in a persistent Na+ current that activates near -70 mV; this phenomenon could underlie the abnormal muscle activity observed in patients with HYPP.     

Congenital myotonia in related kittens

Four closely related domestic shorthair kittens were investigated following the detection of abnormalities in their gait, difficulty opening their mouths and muscle hypertrophy. They walked with a stiff, stilted gait, with the stiffness reducing during exercise. Startling of the kittens resulted in hyperextension of the limbs and falling to lateral recumbency, or spasm of the orbicularis oculi muscle, prolonged prolapse of the nictitating membranes and flattening of the ears. One kitten was intermittently dysphonic. Endotracheal intubation of the anaesthetised kittens was difficult due to an inability to open the mouth to a wide angle, and narrowing of the glottis due to muscle spasm. A diagnosis of congenital myotonia was made based on the clinical signs, the kittens' ages, typical myotonic discharges on electromyography, and the histopathological and histochemical findings in muscle. This is the first report of congenital myotonia in this species.     

Diaphragmatic paralysis

Ankle inversion injuries are the most common injury in sport and yet treatment is controversial. One result is chronic ankle instability, an injury for which criteria for surgical intervention are unclear. This prospective study of 14 patients showed that a large proportion of patients had no detectable abnormality on preoperative investigation, but were subsequently shown to have an abnormality under general anaesthesia. This suggests that a good history of chronic instability is more sensitive an indicator than conventional investigations. Stress views under anaesthesia may confirm the problem.     

Transient weakness and compound muscle action potential decrement in myotonia congenita

Twenty-five Turkish patients with recessive myotonia congenita (RMC), 16 of whom had genetic confirmation, were studied. Nineteen had transient weakness. In the upper extremities, onset age of transient weakness was usually in the early teens. All untreated RMC patients had a compound muscle action potential decrement of > or =25%, usually above 50%, with repetitive nerve stimulation at 10/s for 5 s. Patients with other nondystrophic diseases with myotonia, except 1 patient with dominant myotonia congenita, had no transient weakness and a CMAP decrement below 25%.