Sports-Related Repetitive Traumatic Brain Injury: A Novel Cause of Pituitary Dysfunction

Traumatic brain injury (TBI) is one of the major causes of disability and death, particularly in the young population. Recent clinical studies have demonstrated that TBI-induced pituitary dysfunction occurs more frequently than previously estimated, and this may contribute to delayed diagnosis and treatment of hormonal abnormalities. Today, the popularity of combative sports increases, and athletes who deal with these sports have risks of developing hypopituitarism attributed to repetitive TBIs. Pathogenesis and molecular mechanisms are not completely understood yet. Current studies suggest that athletes who had retired, especially from combative sports, should be screened for hypopituitarism. In this review, we aim to increase the awareness of medical communities, athletes, coaches, and athletic trainers about this issue by sharing the current studies regarding the pituitary dysfunction attributed to repetitive TBI associated with sports.

Evaluation of long-term pituitary functions in patients with severe ventricular arrhythmia: a pilot study

INTRODUCTION

Traumatic brain injury (TBI), subarachnoid hemorrhage (SAH), stroke and cerebrovascular disease (CVD) are identified as risk factors for hypopituitarism. Pituitary dysfunction after TBI, SAH, and CVD may present in the acute phase or later in the course of the event. Chronic hypopituitarism, particularly growth hormone (GH) deficiency is related to the increased cardiovascular morbidity and mortality. In patients with serious ventricular arrhythmias, who need cardiopulmonary resuscitation, brain tissue is exposed to short-term severe ischemia and hypoxia. However, there are no data in the literature regarding pituitary dysfunction after ventricular arrhythmias.

PATIENTS AND METHODS

Forty-four patients with ventricular arrhythmias [ventricular tachycardia (VT), ventricular fibrillation (VF)] (mean age, 55.6 ± 1.8 years; 37 men, 7 women) were included in the study. The patients were evaluated after mean period of 21.2 ± 0.8 months from VT-VF. Basal hormone levels, including serum free triiodothyronine (fT3), free thyroxine (fT4), TSH, ACTH, prolactin, FSH, LH, total testosterone, estradiol, IGF-1, and cortisol levels were measured in all patients. To assess (GH)-insulin like growth factor-1 (IGF-1) axis, glucagon stimulation test was performed and 1 µg ACTH stimulation test was used for assessing hypothalamic-pituitary-adrenal (HPA) axis.

RESULTS

The frequencies of GH, gonadotropin and TSH deficiency were 27.2, 9.0, 2.2%, respectively. Mean IGF-1 levels were lower in GH deficiency group, but it was not statistically significant.

CONCLUSION

The present preliminary study showed that ventricular arrhythmias may result in hypopituitarism, particularly in growth hormone deficiency. Unrecognized hypopituitarism may be responsible for some of the cardiovascular problems at least in some patients.

A five year prospective investigation of anterior pituitary function after traumatic brain injury: is hypopituitarism long-term after head trauma associated with autoimmunity?

Traumatic brain injury (TBI) has been recently recognized as a common cause of pituitary dysfunction. However, there are not sufficient numbers of prospective studies to understand the natural history of TBI induced hypopituitarism. The aim was to report the results of five years' prospective follow-up of anterior pituitary function in patients with mild, moderate and severe TBI. Moreover, we have prospectively investigated the associations between TBI induced hypopituitarism and presence of anti-hypothalamus antibodies (AHA) and anti-pituitary antibodies (APA). Twenty five patients (20 men, five women) were included who were prospectively evaluated 12 months and five years after TBI, and 17 of them also had a third-year evaluation. Growth hormone (GH) deficiency is the most common pituitary hormone deficit at one, three, and five years after TBI. Although most of the pituitary hormone deficiencies improve over time, there were substantial percentages of pituitary hormone deficiencies at the fifth year (28% GH, 4% adrenocorticotropic hormone [ACTH], and 4% gonadotropin deficiencies). Pituitary dysfunction was significantly higher in strongly AHA- and APA-positive (titers ≥1/16) patients at the fifth year. In patients with mild and moderate TBI, ACTH and GH deficiencies may improve over time in a considerable number of patients but, although rarely, may also worsen over the five-year period. However in severe TBI, ACTH and GH status of the patients at the first year evaluation persisted at the fifth year. Therefore, screening pituitary function after TBI for five years is important, especially in patients with mild TBI. Moreover, close strong associations between the presence of high titers of APA and/or AHA and hypopituitarism at the fifth year were shown for the first time.

Growth hormone deficiency due to sports-related head trauma is associated with impaired cognitive performance in amateur boxers and kickboxers as revealed by P300 auditory event-related potentials

OBJECTIVES

It has been recently reported that boxing and kickboxing may cause pituitary dysfunction, GH deficiency in particular. The strong link between poor cognitive performance and GH deficiency due to causes other than head trauma and the improvement of cognitive function after GH replacement therapy have been previously shown. P300 auditory event-related potential (ERP) measure is widely used to evaluate cognitive performance. In this study, we investigated the relation between the GH-IGF-I axis and cognitive performance in boxers and kickboxers.

DESIGN AND PATIENTS

Forty-one actively competing or retired male boxers (n: 27) and kickboxers (n: 14) with a mean age of 29·04 ± 9·30 year and 14 age- and education-matched healthy male controls were included in the study. For neuropsychological tests, the mini-mental state examination (MMSE) and Quality of Life Assessment of GH Deficiency in Adults (QoL-AGHDA) questionnaires were administered. Moreover, cognitive performance was evaluated according to P300 ERPs.

RESULTS

Nine of 41 (21·9%) athletes had GH deficiency. P300 amplitudes were lower at all electrode sites in the GH-deficient group than in controls, and the differences were statistically significant at Fz and Oz electrode sites (P < 0·05). When GH-deficient athletes were compared with GH-sufficient athletes, the P300 amplitudes were lower at all electrode sites in the GH-deficient group; these differences were statistically significant at Fz, Pz and Cz electrode sites (P < 0·05). In all athletes, there were significant negative correlations between IGF-I levels vs P300 latencies, and there were significant positive correlations between IGF-I levels vs P300 amplitudes (P < 0·05).

CONCLUSION

This study provides the first electrophysiological evidence for the close relation between the P300 ERPs and the GH-IGF-I axis in boxers and kickboxers.

Prospective investigation of pituitary functions in patients with acute infectious meningitis: is acute meningitis induced pituitary dysfunction associated with autoimmunity?

Previous case reports and retrospective studies suggest that pituitary dysfunction may occur after acute bacterial or viral meningitis. In this prospective study we assessed the pituitary functions, lipid profile and anthropometric measures in adults with acute bacterial or viral meningitis. Moreover, in order to investigate whether autoimmune mechanisms could play a role in the pathogenesis of acute meningitis-induced hypopituitarism we also investigated the anti-pituitary antibodies (APA) and anti-hypothalamus antibodies (AHA) prospectively. Sixteen patients (10 males, 6 females; mean ± SD age 40.9 ± 15.9) with acute infectious meningitis were included and the patients were evaluated in the acute phase, and at 6 and 12 months after the acute meningitis. In the acute phase 18.7% of the patients had GH deficiency, 12.5% had ACTH and FSH/LH deficiencies. At 12 months after acute meningitis 6 of 14 patients (42.8%) had GH deficiency, 1 of 14 patients (7.1%) had ACTH and FSH/LH deficiencies. Two of 14 patients (14.3%) had combined hormone deficiencies and four patients (28.6%) had isolated hormone deficiencies at 12 months. Four of 9 (44.4%) hormone deficiencies at 6 months were recovered at 12 months, and 3 of 8 (37.5%) hormone deficiencies at 12 months were new-onset hormone deficiencies. At 12 months there were significant negative correlations between IGF-I level vs. LDL-C, and IGF-I level vs. total cholesterol. The frequency of AHA and APA positivity was substantially high, ranging from 35 to 50% of the patients throughout the 12 months period. However there were no significant correlations between AHA or APA positivity and hypopituitarism. The risk of hypopituitarism, GH deficiency in particular, is substantially high in the acute phase, after 6 and 12 months of the acute infectious meningitis. Moreover we found that 6th month after meningitis is too early to make a decision for pituitary dysfunction and these patients should be screened for at least 12 months. In addition, the occurrence of AHA and APA positivity due to acute infectious meningitis was demonstrated for the first time. Further longer-term prospective investigations need to be carried out on a larger cohort of patients to understand the role of autoimmunity in the pathogenesis of late hypopituitarism after acute infectious meningitis.

Posterior pituitary functions are not altered after growth hormone replacement therapy in hypopituitarism due to Sheehan's syndrome

OBJECTIVE

The aim of the present study was to investigate the effects of growth hormone (GH) replacement on posterior pituitary functions of GH-deficient Sheehan's syndrome (SS) patients.

DESIGN

Ten patients with SS and 14 healthy control women were included in this prospective study. All patients were given appropriate hormone replacement therapy other than GH, according to present hormone deficiencies. Patients were euthyroid and eucortisolemic at the time of baseline evaluation. Patients and the control group were evaluated with water-deprivation and saline-infusion tests at baseline and the tests were repeated in patients with SS after 3 months of GH replacement therapy.

RESULTS

According to the water deprivation test, 3 patients had partial central DI at baseline. Urine osmolalities of the patients were slightly lower and plasma osmolalities were significantly higher than the control group at baseline, after water deprivation and following DDAVP injection and after hypertonic saline infusion. The osmotic threshold of serum for thirst perception was found to be significantly higher in SS patients than the control group, GH replacement therapy did not influence the results of water deprivation and saline infusion tests in SS patients.

CONCLUSION

Patients with SS have subtle abnormalities in posterior pituitary functions and the threshold for thirst perception is increased. However GH replacement therapy does not seem to reverse or adversely affect the mildly deteriorated posterior pituitary functions of SS patients.

Hypopituitarism due to sports related head trauma and the effects of growth hormone replacement in retired amateur boxers

Traumatic brain injury (TBI) has been recently recognized as a leading cause of pituitary dysfunction. Current data clearly demonstrated that sports related head trauma due to boxing, kickboxing, and soccer might results in pituitary hormone deficiencies, isolated growth hormone (GH) deficiency in particular. In the present report physiologic dose GH replacement therapy (GHRT) was performed in two GH deficient retired amateur boxers for the first time. The boxers received recombinant GH for 6 months. After 6 months of GHRT there were substantial improvements, but not complete normalization, in the body composition parameters, lipid profiles and quality of life scores in both boxers. These preliminary results suggest that GHRT may have beneficial effects in retired boxers with severe isolated GH deficiency due to sports related head trauma. But more data with higher number of boxers and longer GHRT duration are warranted.

Sleep architecture in Sheehan's syndrome before and 6 months after growth hormone replacement therapy

OBJECTIVE

To characterize the sleep parameters in patients with growth hormone (GH) deficiency in Sheehan's syndrome adults and to assess the effects of 6-month GH replacement therapy (GHRT).

METHODS

Twenty-two women with Sheehan's syndrome, (mean age; 49.1+/-2.2 years), and 12 women with similar age (mean age; 51.3+/-3.8 years) and body mass index as control subjects were included in the study. Under baseline conditions, women received adequate hormone replacement therapy for all hormonal deficiencies other than GH. Twelve patients received recombinant GH (Genotropin; Pfizer Stockholm, Sweden) (treatment group) and eight patients received placebo (placebo group) for 6 months. Two patients had only baseline evaluation and were not followed up prospectively. Two polysomnography (PSG) recordings were performed on the patients group, one in the baseline period and the other at the sixth month of treatment (either GH or placebo). Control group had only baseline PSG.

RESULTS

GH deficient females with Sheehan's syndrome have more NREM (95.9+/-1.5% and 88.6+/-0.9%, respectively; p<0.05), particularly in stage 4 sleep (11.4+/-1.9% and 4.9+/-1.6, respectively; p<0.05), less REM sleep (4.2+/-1.5% and 11.4+/-0.9, respectively; p<0.05) and also less sleep efficiency (69.7+/-3.4% and 81.1+/-2.8%, respectively; p<0.05) when compared to healthy controls. After 6 months of GHRT there was no significant difference in sleep parameters.

CONCLUSION

GH deficiency has sleep disturbing effects on Sheehan's syndrome patients under baseline conditions.

Evaluation of cognitive performance by using P300 auditory event related potentials (ERPs) in patients with growth hormone (GH) deficiency and acromegaly

CONTEXT

Impaired cognitive performance has been demonstrated in adults with GH deficiency and acromegaly by using different neuropsychological tests. P300 event related potential (ERP) application is a well established neurophysiological approach in the assessment of cognitive performance.

OBJECTIVES

Evaluation of cognitive performance by using P300 ERPs has not been reported in acromegaly, and the comparisons of the P300 ERPs between the patients with GH deficiency and GH excess have not been done yet. Therefore present study was designed to investigate the effects of GH deficiency and GH excess on cognitive performance by using P300 ERPs.

DESIGN AND METHODS

The study comprised 19 patients with severe GH deficiency, 18 acromegalic patients and 16 age, education and sex matched healthy controls. Baseline auditory ERPs were obtained at Fz (frontal), Cz (central), Pz (parietal) and Oz (occipital) electrode sites in GH deficient group, GH excess group and control group.

RESULTS

There was a significant difference between mean serum IGF-I levels in the GH deficient and acromegalic patients (48+/-38 ng/ml and 742+/-272 ng/ml, respectively) (P=0.01). The mean P300 latency of the patients with GH deficiency was significantly (P=0.0001) prolonged when compared with that of normal controls and acromegalic patients at all electrode sites. The mean P300 amplitude of the patients with acromegaly was significantly (P=0.005) lower when compared with that of normal controls and GH deficient patients at all electrode sites.

CONCLUSIONS

Using ERPs recordings, the present study indicates the prolongation of P300 latencies in patients with severe GH deficiency and reduction of P300 amplitudes in patients with acromegaly. This study provides the electrophysiological evidence for the presence of cognitive dysfunction in both GH deficiency and GH excess, and different components of the cognitive performance are impaired in these conditions.