UPDATES IN AGGRESSIVE PITUITARY TUMORS.

Aggressive pituitary tumors lie between pituitary adenomas and carcinomas, displaying a particular behavior, with invasion, resistance to conventional therapy and early recurrence. The radiological grading, along with prognostic markers such as Ki-67 proliferation index, p53, MGMT and transcription factors are important factors in establishing the benign, aggressive, or malignant nature of pituitary tumors, with a more accurate treatment strategy. In this article, we report the novelties in defining, classifying, and managing aggressive pituitary tumors and their malignant potential, focusing on clinicopathological, histological, molecular and radiological data.

Muscle activity during mandibular movements in normal and mandibular retrognathic subjects.

PURPOSE: The masticatory muscles function as a unit during precise mandibular positioning movements that occur during such activities as speech, singing, or playing musical instruments. This investigation was designed to assess jaw muscle recruitment patterns during controlled mandibular movement in normal subjects and in patients with mandibular retrognathism. PATIENTS AND METHODS: A computer-integrated electromyography (EMG) and movement monitoring (Selspot) system was used to collect data over 7 seconds of a sagittal border movement (Posselt envelope) of the mandible and 4 seconds each of rest position, light tooth contact, and maximum clench. Fine wire bipolar electrodes were placed into the inferior belly of the lateral pterygoid muscles bilaterally and surface electrodes were placed bilaterally over the anterior belly of the temporalis muscles and the masseter muscles. Ten subjects with Class I occlusion, normal cephalometric values, and an absence of temporomandibular joint (TMJ) dysfunction were compared with 12 patients with mandibular retrognathism, Class II malocclusion, and an absence of clinical signs of TMJ internal derangement before and after a bilateral sagittal split and advancement of the mandible. RESULTS: There was a wide variation in standard deviations of EMG activity for the lateral pterygoid muscles in the retrognathic patients compared with normal controls before surgery (P < .05). In light tooth contact, temporalis muscle activity increased after surgery with respect to both control and the presurgical levels (P < .05, P < .005, respectively). In maximum clench, activity in all muscle groups in the retrognathic patients, both before and after surgery, were below that of control subjects (P < .005). The lateral pterygoid muscles showed late recruitment, with low EMG activity levels during the forward movement phase of the envelope, before surgery compared with controls (P < .001). After surgery, the lateral pterygoid muscle showed early recruitment in the forward movement similar to control levels. CONCLUSION: The masticatory muscles function as a unit during mandibular positioning movements. Patients with mandibular retrognathism have different muscle recruitment patterns from those of normal subjects with the mandible at rest and during mandibular movement. After orthognathic surgery, adaptation occurs in the phasic timing of jaw muscle activity.

Agonist and antagonist activity during voluntary upper-limb movement in patients with stroke.

Forty-four patients with hemiplegia following stroke and 10 nondisabled subjects were studied to examine the contributions inadequate motor unit recruitment and co-contraction attributable to impaired antagonist inhibition play in the movement disorder of the hemiplegic arm. Electromyographic data were recorded from agonist and antagonist muscles while subjects attempted six specified tasks. Data from subjects who could complete the tasks were compared with those who could not complete the tasks. Differences between the two groups were found in the electromyographic data obtained from the agonist muscles. Electromyographic values were consistently and significantly lower in patients who were unable to complete the tasks than in patients who were able to complete the tasks. In the antagonist muscles, a significant difference was noted only once; in this case, the EMG values were again lower in the group of patients who were unable to complete the task. Inadequate recruitment of agonists, not increased activity in the antagonists, was a consistent finding in patients who were unable to carry out the movement tasks. This study theoretically supports aiming treatment efforts at improving motoneuron recruitment rather than reducing activity in antagonists while retraining arm function.

Effects of chronic cerebellar stimulation (CCS) setting on the gait and speech of a spastic cerebral palsy adult.

A single (N = 1) spastic cerebral palsy adult who had experienced Chronic Cerebellar Stimulation (CCS) for 9 years without any change in the stimulator settings was assessed at six different stimulator settings. These voltage settings varied from 0 volts to 40 volts and frequencies of stimulation from 0 to 200 Hz. Stimulation was with bipolar rectangular pulses with less than 0.2 C/mm2 charge per phase. Responses measured at each setting were quantitative gait, speech, and somatosensory evoked potential measurements. Additional clinical assessments were done by a neurologist and speech therapist. Alteration in stimulator settings occurred 1 week apart to allow for stabilization and all assessments were completed in the same sequence each day. None of the individual stimulator settings were known to any of the assessors or to the patient. The results showed consistently that the patient's gait and speech were poorest when the stimulator was switched off completely. Switching on the stimulator caused improved function according to all assessments. There was consistent improvement in gait and speech when the rate of the cerebellar stimuli was high (for voltages between 0 and 40 V). Changing the voltage (within the range 0 to 40 V), while keeping the frequency of stimulation constant, did not appear to have as much effect. This preliminary evaluation suggests that the technique of CCS is safe and can improve function in a measurable manner.

The effects of prostanoids on estrogen-dominated rat myometrial longitudinal muscle in vitro.

The purpose of these experiments was to characterize the contractile response of longitudinal muscle from the estrogen-dominated rat uterus to natural and synthetic prostanoids. The biological significance is 1) to provide evidence for or against a physiological role for each natural prostanoid in the regulation of myometrial activity, 2) to determine if each prostanoid has pharmacological potential for the manipulation of myometrial activity, and 3) to understand the structural requirements for prostanoid action on the myometrium. All analogs tested produced excitation of the myometrium in vitro through what appeared to be a direct action on the muscle. The order of potency of the natural prostanoids was prostaglandin (PG) F2 alpha = PGD2 = PGE2 = PGE1 greater than PGA2 = PGB2 = 6-keto-PGF1 alpha. This order of potency was not consistent with any single currently recognized prostanoid receptor. Furthermore, PGF2 alpha had an EC50 (effective concentration that produces 50% of the maximal response) of 0.5 microM, which was low in comparison to other PGF2 alpha-sensitive tissues. There were large differences in the maximum tension developed in response to the prostanoids tested, only PGF2 alpha, PGE2 and 6-keto PGF1 alpha were full agonists. Although the simplest explanation of these data was that the rat uterus contains a single novel type of prostanoid receptor, the existence of multiple receptor subtypes could not be disproved. Evidence from the effect of synthetic analogs suggested that neither thromboxane A2 nor PGI2 are physiological regulators of activity in this tissue.

Lateral pterygoid muscle activity in mandibular retrognathism and response to mandibular advancement surgery.

Electromyographic patterns of muscle activity were recorded in 11 patients with mandibular retrognathism and compared with ten normal subjects. Categorization of facial morphology was based on standard cephalometric data. Seven patients in the retrognathic group have been studied 1 year after mandibular-lengthening surgery. A computer-based data acquisition and analysis system with a Selspot movement monitoring system was used to record and quantify simultaneously both mandibular movement patterns and associated electromyographic data. Of particular interest was the pattern of activity for the lateral pterygoid muscles of all patients in the retrognathic group compared with controls. Both the ipsilateral and contralateral lateral pterygoids contracted during either right or left lateral excursions for eight of the 11 patients in the retrognathic group compared to aphasic activity during this movement as expected in the control group. However, all seven of the patients tested 1 year after mandibular lengthening demonstrated normal aphasic firing patterns of the lateral pterygoid muscles (inferior belly) during right and left lateral excursions. The retrognathic group of patients also demonstrated abnormal recruitment patterns of the lateral pterygoid muscles during border movements of the mandible in the preoperative stage. Recruitment patterns approached normal levels after mandibular advancement surgery. The number of patients studied did not permit accurate statistical analysis. However, a trend is apparent that demonstrates previously unreported abnormal activity patterns of the lateral pterygoid muscles and an adaptive response of these muscles to orthognathic surgery.