Mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) associated with hypothalamo-pituitary hypofunction--a case report

A case of 25-year-old woman with mitochondrial encephalomyopathy, lactic acidosis and stroke-like episodes (MELAS) was reported. She had short stature, episodic vomiting with headache, several episodes with homonymous hemianopsia, progressive intellectual decline, generalized convulsion, muscular atrophy, sensory disturbance on the left side of the body, and primary amenorrhea. Lactate, pyruvate and the lactate to pyruvate ratio were elevated in the serum and cerebrospinal fluid. Muscle biopsy revealed ragged-red fibers. On electron microscopy there were subsarcolemmal aggregations of abnormal mitochondria with proliferation of crista and inclusions. Activities of the respiratory chain enzymes of the muscle mitochondria were normal. She showed a failure of GH response to arginine and levodopa and delayed response of serum GH to growth hormone releasing factor (GRF). She also showed decreased gonadotropin levels and delayed response of the hormone to LH-RH. In this case, a dysfunction of the hypothalamo-pituitary axis may be related to the short stature and primary amenorrhea. It is suggested that the hypothalamo-pituitary hypofunction may be one of the characteristic features in MELAS.     

Ictal Laughter Associated with Paroxysmal Hypothalamopituitary Dysfunction

Summary: Purpose : Seizures with ictal laughter (also termed gelastic seizures) have been associated with hypothalamic hamartomas and precocious puberty. It is not known, however, where in the brain such seizures originate. We describe a child with gelastic seizures and a hypothalamic lesion (probably a hamartoma) in whom two dysfunctional phenomena were observed.
Results : First, there was a hyperperfusion in the hypothalamopituitary areas shown by ictal [^99m]Tc hexamethyl-propyleneamine oxime (HM-PAO) single photon-emission computed tomography (SPECT). Second, there was an ictal pulse of gonadotropins, 17β-estradiol, and growth hormone well above the normal limits in one of the seizures.
Conclusion : These findings suggest that gelastic seizures associated with hypothalamic hamartomas are generated in the hypothalamus or in its neighboring regions and that these seizures may cause paroxysmal dysfunction of the hypothalamo-pitutary axis.     

Immunohistochemical studies on the somatostatin- and growth hormone-releasing factor (GRF)-neurons in the hypothalamus of the novel dwarf rat; the spontaneous dwarf rat (dr)

Immunoreactivities of somatostatin and growth hormone-releasing factor (GRF) in the hypothalamus of spontaneous dwarf rats (SDRs, gene symbol; dr), which show isolated growth hormone (GH) deficiency, and normal rats were studied with an avidin-biotin complex (ABC) immunohistochemical method. Somatostatin and GRF immunoreactivities were observed in the median eminence and each afferent nucleus with no difference between these animals. The observation suggests that the etiology of the GH deficiency lies in GH cells themselves and is not hypothalamic in origin. This observation indicates that the SDR is a new model animal for type I dwarfism.     

The Effects of a Growth Hormone-Releasing Peptide and Growth Hormone-Releasing Factor in Conscious and Anaesthetized Rats

The growth hormone (GH) releasing ability of GH-releasing factor (GRF) and a GH-releasing hexapeptide, CHRP, have been studied in anaesthetized and conscious male and female rats. The GH responses to GHRP in anaesthetized rats were inconsistent, and this peptide was much less potent than GRF. Continuous iv infusions of GRF or GHRP both caused an initial GH release which was not maintained, and further GH release could be elicited by injection of GRF during an infusion of GHRP and vice versa. In contrast, conscious rats were much more sensitive to GHRP. Infusions of GHRP or GRF both caused an initial GH release. With GRF infusions, GH release continued in the normal episodic pattern whereas with GHRP infusion, GH secretion remained elevated over baseline and the normal pulsatile rhythm was disrupted. Plasma GH levels fell after stopping GHRP infusion, without an immediate resumption of normal GH pulsatility. Conscious male rats responded intermittently to injections of GRF given iv every 45 min, but when such serial injections of GRF were given during a continuous iv infusion of GHRP, the GH responses to GRF became regular and more uniform. These results suggest that GHRP prevents the normal cyclic refractoriness to GRF in male rats by disrupting cyclic somatostatin release. The greater potency of GHRP in conscious rats may also depend on the release of endogenous GRF since passive immunization with an anti-GRF serum reduced the plasma GH response to GHRP infusion. Thus in the conscious animal, GHRP may release GH by complex actions at both a hypothalamic and pituitary level.     

Growth hormone (GH) response to clonidine and growth hormone releasing factor (GRF) in normal controls

To investigate the relationship between the plasma growth hormone (GH) response to provocative challenge with the hypothalamic peptide growth hormone-releasing factor (GRF) and the alpha 2-adrenergic agonist clonidine, we administered GRF (1 microgram/kg), clonidine (2 micrograms/kg), and placebo to 21 healthy normal controls (13 men and eight women). Both clonidine and GRF caused significant increases in plasma GH levels over baseline. The peak GH-responses to GRF and clonidine were similar (GRF = 8.7 +/- 6.7 ng/ml; clonidine = 6.5 +/- 5.9 ng/ml; Wilcoxon test: s = 361, z = -1.31, p = NS). The GH responses to GRF and clonidine were significantly correlated (rs = 0.62, n = 20, p = 0.004). Unexpectedly, we found that five of the 21 (26%) normal controls had no GH secretory response to either GRF or clonidine. There was a modest gender effect with clonidine (men greater than women; p less than 0.06) and a negative correlation between GH secretion and age with both GRF and clonidine. Neither GRF nor clonidine had an effect on cortisol levels (DRUG x TIME interaction: F(8,152) = 0.60, p = NS). These findings are consistent with animal studies suggesting that the GH response to clonidine is mediated by GRF. The age and gender effects underscore the importance of careful matching for these factors in studies measuring the GH secretory response.     

Pituitary reserve of growth hormone in adolescent patients with cerebral palsy and mental retardation

The pituitary reserve of growth hormone (GH) was studied in 11 severely handicapped boys (14 approximately 18 years old) with mental retardation and cerebral palsy (CP); athetotic type 4 cases, and spastic type 7 cases. Serum GH was determined before and after intravenous injection of 1 ng/kg growth hormone releasing factor (GRF) or oral administration of 0.1 mg/m2 clonidine. The athetotic type patients showed low somatomedin C (Sm C) concentrations (0.31 +/- 0.11 U/ml), poor responses to clonidine, and good responses to GRF. The spastic type patients showed subnormal responses to GRF although their Sm C was normal (0.91 +/- 0.43 U/ml). Clinically, the stature was small, and the puberty was delayed in the former. The levels of plasma testosterone were significantly lower than those in the latter. It is concluded that athetotic type CP was associated with hypothalamic GRF deficiency and spastic type CP was associated with reduced pituitary reserve of GH.     

Hypothalamic obesity due to hydrocephalus caused by aqueductal stenosis.

A case is presented of 14 year old female with hypothalamic obesity due to hydrocephalus caused by aqueductal stenosis. Evidence of hypothalamic obesity included 1) acute hyperphagia and weight gain, 2) neuroradiology showed hydrocephalus with focal enlargement of the third ventricle, 3) endocrinological studies revealed hyperinsulinaemia and impaired growth hormone (GH) response to arginine, but normal GH response to growth hormone-releasing factor (GRF) and 4) Torkildsen's ventriculo-cisternal shunting resulted in improvement in hyperphagia and obesity.     

Intractable gelastic seizures during infancy: ictal positron emission tomography (PET) demonstrating epileptiform activity within the hypothalamic hamartoma

Gelastic seizures comprise a very rare form of epilepsy. They present with recurrent bursts of laughter voices without mirth and are most commonly associated with the evolution of a hypothalamic hamartoma. The purpose of this article is to describe the second reported ictal fluorodeoxyglucose-positron emission tomography study in a unique case of an infant with intractable gelastic seizures since the neonatal period associated with a hypothalamic hamartoma. The patient presented at 4 months old with recurrent, almost persistent, gelastic seizures consisting of laughter bouts without mirth. The seizures were noticeable at the first week of life and increased in frequency to last up to 12 hours, namely status gelasticus. These gelastic fits were accompanied with focal motor seizures, including unilateral right-eye blinking and mouth twitching. Developmental mile-stones were intact for age. Magnetic resonance imaging of the cortex demonstrated a large hypothalamic hamartoma within the third ventricle, hampering cerebrovascular fluid drainage of the lateral ventricles. An electroencephalography was nondiagnostic. Ictal fluorodeoxyglucose-positron emission tomography demonstrated a large circumscribed hypermetabolic region within the location of the hypothalamic hamartoma, representing localized intense epileptiform activity. The infant became instantly free of all seizure types given minute doses of oral benzodiazepine (clonazepam) and remains completely controlled after 12 months. Her overall development remains intact. This ictal fluorodeoxyglucose-positron emission tomography is the second reported study verifying that the main source of the epileptic activity inducing gelastic seizures originates from the hypothalamic hamartoma itself; therefore, a complementary fluorodeoxyglucose-positron emission tomography study should be considered in any patient presenting with intractable gelastic seizures, especially in those associated with hypothalamic hamartoma, in order to localize the region of epileptiform activity amenable to surgical resection if intensive drug therapy fails.     

Giant hypothalamic hamartoma and dacrystic seizures.

Ictal crying is a rare type of epileptic seizure associated with hypothalamic hamartoma and with other lesions such as tumours, vascular malformations, hippocampal sclerosis, or cerebral infarction. We describe the case of an infant with gelastic, dacrystic and other types of seizures associated with a giant hypothalamic hamartoma, and present a video sequence of dacrystic seizures. Dacrystic episodes presented in clusters at sleep onset, initially in the form of moaning followed by face-flushing that rapidly evolved to crying, associated with a lateral and upper deviation of both eyeballs, along with clonic aspects of the eyelids. After a few seconds, the crying became less intense, she stared, and oro-alimentary automatisms became prominent along with some slow horizontal movements of the eyes and the head. Following surgery, at the age of nine months, the gelastic seizures stopped, but dacrystic seizures persisted. [Published with video sequences].     

Inhibition of growth hormone-releasing factor suppresses both sleep and growth hormone secretion in the rat.

To study the possible involvement of hypothalamic growth hormone-releasing factor (GRF) in sleep regulation, a competitive GRF-antagonist, the peptide (N-Ac-Tyr1,D-Arg2)-GRF(1-29)-NH2, was intracerebroventricularly injected into rats (0.003, 0.3, and 14 nmol), and the EEG and brain temperature were recorded for 12 h during the light cycle of the day. Growth hormone (GH) concentrations were determined from plasma samples taken at 20-min intervals for 3 h after 14 nmol GRF-antagonist. The onset of non-rapid eye movement sleep (NREMS) was delayed in response to 0.3 and 14 nmol GRF-antagonist, the duration of NREMS was decreased for one or more hours and after 14 nmol EEG slow wave amplitudes were decreased during NREMS in postinjection hour 1. The high dose of GRF-antagonist also suppressed REMS for 4 h, inhibited GH secretion, and elicited a slight biphasic variation in brain temperature. These findings, together with previous observations indicating a sleep-promoting effect for GRF, support the hypothesis that hypothalamic GRF is involved in sleep regulation and might be responsible for the correlation between NREMS and GH secretion reported in various species.     

A case of MERRF associated with chronic pancreatitis

We report the first case to our knowledge of chronic pancreatitis associated with mitochondrial encephalopathy with the A8344G mitochondrial DNA (mtDNA) mutation. This 10-year-old-girl had suffered from recurrent abdominal pain with elevated serum amylase and lipase since the age of 6, and easy fatigability, tremor and astatic seizures since the age of 8. A biopsy of quadriceps muscle revealed ragged-red-fibers and cytochrome c oxidase deficiency. Analysis of mtDNA in peripheral blood identified an A8344G mutation in the mitochondrial tRNA(Lys) gene. Taken together with physical signs of myoclonic seizures and cerebellar dysfunction, we diagnosed her as myoclonic epilepsy with ragged-red fibers associated with chronic pancreatitis. Although no association between mitochondrial disease and pancreatitis has yet been established, this case suggests it is necessary to consider the participation of mitochondrial abnormality in the pathogenesis of recurrent pancreatitis.     

Effect of alpha-methyl-p-tyrosine and an antiserum to rat growth hormone (GH)-releasing factor (GRF) on plasma GH secretory profile during a continuous infusion of human GRF in rats

The effects of alpha-methyl-p-tyrosine (alpha-MT) and an antiserum specific to rat growth hormone-releasing factor (GRF) on growth hormone (GH) secretory profile during a 6-h continuous infusion of human GRF(1-44) NH2 were observed in unrestrained adult male Wistar rats. All rats were provided with two indwelling cannulae; one in the right atrium for undisturbed blood collection and the other in the inferior vena cava for 0.9% NaCl or GRF infusion. GRF was administered by an infusion pump at a dose of 50 ng/kg b.wt./min ma GH levels during baseline period were low with little fluctuation. GH secretion was augmented significantly during continuous GRF infusion in control rats but interpeak intervals remained unaltered. When an antiserum specific to rat GRF was administered, episodic GH secretion was abolished. In these rats, pulsatile GH secretion indistinguishable from that of control rats was observed in the continuous presence of human GRF. Although alpha-MT inhibited episodic GH secretion, alpha-MT-treated rats exhibited high-frequency, low-amplitude episodic GH secretion and elevated baseline levels during the stimulation. There were no differences in the amount of GH secreted during GRF infusion between rats that had received either alpha-MT or antiserum to rat GRF. Since GH secretion to GRF is determined largely by somatostatin, the results suggest that phasic release of somatostatin plays an important role in determining the rhythmicity of episodic GH secretion, and that it is modulated by alpha-MT but not by the immunoneutralization of GRF.     

A boy with muscle weakness, hypercarbia, and the mitochondrial DNA A3243G mutation

The point mutation in the mitochondrial genome tRNA(Leu_ (A3243G) is associated with the syndrome of mitochondrial encephalomyopathy, lactic acidosis, and strokelike episodes (MELAS). We report a boy presenting with respiratory compromise and hypercarbia owing to severe muscle weakness. Historically, he demonstrated idiopathic growth hormone deficiency, retarded bone age, and exercise avoidance. Owing to severe respiratory compromise out of proportion to expected recovery, a metabolic work-up was performed. Muscle biopsy demonstrated abnormal mitochondria structure and heteroplasmic A3243G mutation. Idiopathic growth hormone deficiency and retarded bone age have not been previously reported in MELAS, and these findings delayed testing for mitochondrial disease. This case demonstrates that isolated muscle weakness in the context of other organ system abnormalities should make the investigator consider MELAS. (J Child Neurol 2006;21:77-79).     

Thyrotropin-releasing hormone mediates growth hormone release induced by milk and nursing in neonatal rats

Previous evidence from this laboratory suggested that growth hormone (GH) release induced by milk in vitro and by nursing in vivo from neonatal rat pituitary glands is mediated by an alternative GH-releasing factor(s) (GRF) distinct from GH-releasing hormone (GHRH(1-43) ). In the present experiments we tested whether thyrotropin-releasing hormone (TRH) could fulfil the criteria of this alternative GRF in neonatal rats. The water-soluble fraction of rat milk (infranatant, prepared by ultracentrifugation) and its methanol/acetic acid extract (milk-borne peptides) stimulated GH release from perifused pituitary glands obtained from 2-day-old rats. Dialysis of the infranatant (mol wt cut-off: 2,000) against 500 volumes of culture medium at 4°C eliminated its GH-releasing activity in the perifusion system, while the infranatant retained its full GRF-like activity when incubated at 4°C without dialysis. The milk-borne GRF eluted as a single peak and coeluted with TRH in a combined gel permeation chromatography (Sephadex G-10) and perifusion set-up. Prolactin secretion was also stimulated simultaneously with the release of GH induced either by milk or by TRH. In a stepwise C(18) reversed-phase chromatography, milk-borne GRF was highly hydrophilic and coeluted with synthetic TRH. The in vitro GH-releasing bioactivities of synthetic TRH and a milk extract purified in C(18) reversed-phase chromatography were abolished by proline-specific endopeptidase. Thus, TRH and milk-borne GRF displayed similar molecular weights, hydropathic characteristics and proteolytic enzyme resistance. In vivo, nursing (which has been reported as a potent stimulus of GH secretion even in the absence of milk-intake) increased serum GH levels in 2-day-old pups. A supramaximal dose of TRH (10 ng/g intraperitoneally) stimulated GH release in 2-day-old pups separated from their mothers for 6 h to a similar extent as nursing. Nursing-induced levels of serum GH were not further elevated by TRH. This failure of TRH to further increase serum GH levels was not due to a maximal GH output by the neonatal pituitary gland, since the GH release induced by the serotonin precursor 5-hydroxy-L-tryptophan was augmented either by TRH or by nursing. These data provide evidence that the milk-borne GRF-like activity in vitro is indistinguishable from TRH, and suggest that TRH (probably of hypothalamic origin) might be the mediator of the nursing-induced release of GH in vivo as a physiological GRF in neonatal rats.     

A novel hypothalamic-dispersed pituitary co-perifusion model for the study of growth hormone secretion.

This study presents a novel, in vitro, hypothalamic-dispersed pituitary co-perifusion system (HPPS) developed to examine the influence of the hypothalamus on pituitary growth hormone (GH) secretion in a controlled environment. In this perifusion system, dispersed rat pituitary cells were loaded onto Biogel P-2 (P-2) beads in a 0.5-ml plexiglas chamber and were submerged in a 37 degrees C water bath. After stabilization, two hypothalami were placed into each chamber on a thin layer of P-2 beads and the chamber was re-equilibrated. To test the system, pituitary cells were stimulated either directly with growth hormone-releasing factor (GRF) or indirectly via the hypothalamus, with clonidine, an alpha 2-adrenergic (alpha 2) receptor agonist. Perifusion of HPPS or pituitary cells with GRF (40 ng/ml) induced a substantial endogenous GH surge. Clonidine (2 x 10(-8) M) treatment stimulated a GH surge in HPPS chambers, but not in chambers containing only pituitary cells. Thus, somatotrophs respond to hypothalamic factors released in response to clonidine and not directly to alpha 2 stimulation. To determine if the components involved in GH feedback are present in the perifusion system, HPPS chambers were sequentially perifused with hGH, clonidine, and GRF. hGH pretreatment suppressed the clonidine but not the GRF-induced GH surge(s) observed in chambers perifused with clonidine and GRF only. In chambers only containing pituitary cells, GH was only increased in response to GRF when sequentially perifused with all three substances. This study demonstrates the dynamic interaction between the hypothalamus and pituitary in the regulation of GH secretion in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)     

Gelastic seizure with tectal tumor, lobar holoprosencephaly, and subependymal nodules: clinical report

Gelastic seizures are characterized by inappropriate, stereotyped laughter and are often first recognized when other epileptic manifestations occur. They are frequently associated with hypothalamic hamartomas. Central nervous system developmental abnormalities are rarely reported with gelastic seizures. There is only one case report of gelastic seizure caused by holoprosencephaly. We report a 2-year-old girl with multiple brain structural abnormalities including tectal tumor (possibly hamartoma), multiple subependymal nodules, and holoprosencephaly. She developed seizures during the newborn period and presented with gelastic seizure and simple partial seizure at 3 months of age.     

Psychogenic gelastic seizures in a patient with hypothalamic hamartoma

Gelastic seizures are classically associated with hypothalamic hamartoma. The most effective treatment for gelastic epilepsy is surgery, although confirming that a hypothalamic hamartoma is an epileptic lesion prior to surgical intervention is challenging. Here, we report the case of a patient with a hypothalamic hamartoma who was diagnosed with psychogenic non-epileptic gelastic seizures using video-EEG monitoring. [Published with video sequences].     

Surgical treatment of extra‐hypothalamic epilepsies presenting with gelastic seizures

We provide an overview of the surgical outcome of extra‐hypothalamic epilepsies with gelastic seizures based on an original case report and a summary of the literature. Twenty‐two articles providing information on the outcome of resective surgery in 39 patients with extra‐hypothalamic gelastic seizures from the temporal (19 patients) or frontal lobe (20 patients) were selected. We add another case of temporal lobe gelastic seizures to the literature with a video demonstrating the mirthful component of this patient's laughing seizures. Drug‐refractory cases of gelastic seizures from the temporal or frontal lobes are amenable to surgical treatment following thorough investigation with imaging, as well as scalp and intracranial EEG.     

Intracerebroventricular administration of the rat growth hormone (GH) receptor antagonist G118R stimulates GH secretion: evidence for the existence of short loop negative feedback of GH

Pulsatile growth hormone (GH) secretion is regulated by three hypothalamic factors, growth hormone-releasing hormone (GHRH), somatostatin and the natural ligand for the GH secretagogue receptor (Ghrelin). These factors and their effects are, in turn, affected by short loop feedback of GH itself. To test the hypothesis that hypothalamic GH receptors are involved in the ultradian rhythmicity of pituitary GH secretion, the rat GH receptor antagonist (G118R) was administered to adult male rats by intracerebroventricular (i.c. v.) injection and the effects on spontaneous GH secretion were studied. Normal saline was administered i.c.v. to eight control rats. Mean GH concentrations increased significantly in the rat treated with G118R compared to rats that received normal saline. The pulse amplitude rose by a mean of 33.3 ng/ml and the total area under the curve increased by a mean of 15 061 ng/ml x min. The number of GH peaks did not change significantly following G118R. These data suggest that GH regulates its own secretion by acting directly on hypothalamic GH receptors.     

Hypothalamic growth hormone deficiency and supplementary GH therapy in two patients with mitochondrial myopathy,encephalopathy, lactic acidosis and stroke-like episodes

Two pediatric patients with mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes were diagnosed with growth hormone deficiency with the primary lesion identified as the growth hormone-releasing factor producing cells of the hypothalamus. Stimulation tests with insulin, levodopa and sleep did not overcome the deficient pattern of growth hormone secretion. By comparison, the growth hormone-releasing factor stimulation test generated a normal growth hormone response in these two patients. Growth hormone supplementary therapy was effective in terms of growth gain without adverse effects.