Analysis of intracranial volume in apert syndrome genotypes

OBJECTIVE

Apert syndrome is caused by a mutation of the fibroblastic growth factor type 2 gene and in nearly all of the cases where the mutation has been identified it occurs in one of two adjacent sites of the gene, either position 252 or position 253. There is currently uncertainty whether a worse neurosurgical outcome occurs in association with a particular genotype. We investigated whether there were clinically subtle (but relevant) morphological differences in the craniofacial skeleton, which would result in differences in the intracranial volume, which might account for apparent differences in surgical outcome.

METHOD

Three-dimensional CT scans of pre-operative Apert syndrome whose genotype had been identified had the intracranial volume measured using the Cavalieri estimator with correction for partial voluming effects. The values were compared to age and sex normals and then the two genotypes compared.

RESULTS

Intracranial volumes were measured for 22 cases, 16 with the 252 mutation and 6 with the 253 mutation.

CONCLUSIONS

All cases except two had greater than their sex- and age-adjusted mean normal intracranial volumes. For the 252 and 253 genotypes there were no discernible differences in intracranial volumes between the two genotypes.

Frontoethmoidal encephalomeningocele: new morphological findings and a new classification

Given a lack of a comprehensive classification for the frontoethmoidal encephalomeningocele (FEEM), clinical, photographic, and computed tomography (CT) data of 23 nonoperated patients were reviewed. Extracranial pathological findings of interest included herniation masses, facial deformities, and frontonasal bone morphology. Intracranial pathological findings of interest included morphology of the anterior cranial floor and brain malformations. Stereographic software processed data from a new-generation CT scanner into three-dimensional pictures that revealed some interesting morphological findings not often appreciated (eg, herniation mass without underlying external bone defect; mass at location far from external bone defect ["sequestrated cephalocele"]; new type of external bone defect characterized by a combination of nasoethmoidal and naso-orbital defects; correlation between mass, external bone defect, and exit pathway of herniation). Given these observations plus current knowledge available in the medical literature, a new classification system was developed that covers phenotypes and severity of the disease. The "FEEM classification" is an alphanumeric system based on facial deformities, external bone defect, exit pathway of herniation, and malformation of brain. It was tested in 42 patients for usability and validity. When combined with a newly designed "FEEM diagram," relevant pathological findings can be recorded in an objective manner so that diagnosis becomes more precise and uniform and comparison of outcome is possible. It also emphasizes the fact that FEEM has a range of manifestations governed by dynamic interaction between structural defects and herniation. Each clinical entity is a final result of its own disease course (stable, progressive, or regressive FEEM), with a varying degree of communication between the external mass and the central nervous system.

From Birth to Maturity: A Group of Patients Who Have Completed Their Protocol Management. Part I. Unilateral Cleft Lip and Palate

The optimal management of the cleft lip and palate patient from birth to completion of treatment presents a formidable challenge to the plastic surgeon and the associated health care system. The multidisciplinary team approach for the management of these patients is widely accepted. However, a paucity of literature exists discussing specific protocol management, interventions, and the long-term outcomes of patients who have completed a strict treatment protocol with a consistent multidisciplinary team. The aim of this study was to present the details of the specific management protocol at the Australian Craniofacial Unit for cleft lip and palate patients and to present a group of patients who have completed this specific protocol and discuss the details of their long-term care. During a 28-year period from 1974 to 2002, the records of 337 patients treated for unilateral cleft lip and palate were evaluated. Of these 337 patients, 22 have completed the same specific protocol management. The same surgeon (David, the senior author) has been responsible for performing all operative interventions and for overseeing the care of each of the 22 patients, ensuring that the treatment protocol has been executed appropriately and without deviation. The interventions and outcomes were analyzed on the basis of speech, hearing, nasal airway, occlusion, psychosocial adjustment, and appearance. Because of the large volume of data and potential differences in outcomes, the authors' intention is to present this as part I of a four-part series beginning with unilateral cleft lip and palate. The results of isolated cleft palate, isolated cleft lip, and bilateral cleft lip and palate will be presented as parts II, III, and IV, respectively. Speech results were assessed as normal speech, mild abnormality, or severe abnormality by objective measures, and intervention for velopharyngeal insufficiency was noted. Seventeen patients were rated as having normal speech. Four patients were rated as having mild speech abnormality, one patient was rated as having severe speech abnormality, and seven patients required surgery for velopharyngeal insufficiency. Hearing results were measured objectively, and good hearing results were obtained in 18 cases. Five patients required tympanoplasty. All patients required alveolar bone grafting. The high Le Fort I osteotomy was performed in six cases. Bimaxillary surgery was performed in one case. Of all the patients assessed from birth to maturity, 13 required between three and five surgical interventions, and nine required six operations or more. Further details and photographs of preoperative and postoperative examples are provided.

World War I: the genesis of craniomaxillofacial surgery?

Herbert Moran enlisted in the Royal Army Medical Corps early in World War I. His autobiography captures the impact of contemporary experience of wartime gunshot wounds, seen in vast numbers and with little understanding of the requirements of wartime surgery. Wounds of the face and brain were numerous, especially in trench fighting. In France, Germany, Britain and elsewhere, surgeons and dentists collaborated to repair mutilated faces and special centres were set up to facilitate this. The innovative New Zealand surgeon Harold Gillies developed his famous reconstructive techniques in the Queen's Hospital at Sidcup, with the help of dental surgeons, anaesthetists and medical artists. The treatment of brain wounds was controversial. Many surgeons, especially on the German side, advocated minimal primary operative surgery and delayed closure. Others advocated early exploration and immediate closure; among the first to do so was the Austro-Hungarian otologist Robert Bárány. In 1918, the pioneer American neurosurgeon Harvey Cushing published well-documented proof of the desirability of definitive operative management done as soon as possible. Few World War I surgeons developed their knowledge of plastic surgery, neurosurgery and oral surgery in post-war practice. An exception was Henry Newland, who went on to pioneer the development of these specialties in Australasia. After World War II, the French plastic surgeon Paul Tessier created the multidisciplinary subspecialty of craniomaxillofacial surgery, with the help of his neurosurgical colleague Gérard Guiot, and applied this approach to the correction of facial deformities. It has become evident that the new subspecialty requires appropriate training programs.

Mandibular Lengthening by Distraction for Airway Obstruction in Treacher-Collins Syndrome: The Long-Term Results

Mandibular lengthening by distraction was performed in a 6-year-old severely affected Treacher-Collins syndrome patient who was tracheostomy dependent. As previously reported, this procedure permitted tracheostomy removal once distraction was complete. Now that the patient is skeletally mature, the long-term results of this intervention are reported with regard to his clinical outcome and an assessment of the anatomical changes in the upper airway during growth. Although the distraction could be considered a success in that it enabled permanent decannulation and improved the minimum cross-sectional area of the upper airway, there was no further increase in the minimum cross-sectional area of the upper airway during childhood growth. It is significant that the abnormal growth pattern of the mandible, which is characteristic of this syndrome, did not alter from its preoperative pattern once distraction was completed.

Teratomas of the head and neck region

BACKGROUND

Teratomas are exceptionally rare malformations in the head and neck region. They are mostly benign but as a direct result of their rarity, most clinician's experience of these tumours is very limited, and consequently most of the associated literature consists of single case reports. In this paper, however, all the cases managed by a major Craniofacial Unit (the Australian Craniofacial Unit) were reviewed to attempt to identify common problems encountered in their management.

MATERIAL AND METHODS

All cases managed by the Australian Craniofacial Unit over the last 25 years were reviewed. In total a series of nine cases was identified, but two were seen and operated on in overseas centres and the data in these cases were incomplete, and have been excluded from the study. Case note, radiology and pathology review was undertaken to collect data.

RESULTS

In total a series of seven cases was identified as suitable for inclusion in this study. Six of these have had a minimum of 9 years follow-up, three having completed growth.

CONCLUSION

The initial and subsequent management demonstrates that these tumours when benign can be successfully removed, but depending on the affected site may require continued multidisciplinary management until growth has finished.

Advances in the management of the craniosynostoses

The spectacular beginning of craniofacial surgery in the modern era involved a case of craniosynostosis. Progress from that time to the present in the development of our understanding of this disease process and its management reflects the wider progress in the development and institutionalization of the discipline of craniofacial surgery. Complex surgical interventions have led the way to multidisciplinary units that have developed a greater understanding of the pathology and natural history of the craniosynostoses. New technologies have been developed to further advance the surgical techniques and these can now be evaluated by the institutions that have spawned them. This paper deals with the development of the discipline, the current status of the management of craniosynostosis, both syndromal and non-syndromal, and discusses the technological advances including imaging, distraction osteogenesis and the current status of genetic investigations.

Effects of chronic paroxetine treatment on dialysate serotonin in 5-HT1B receptor knockout mice

The role of serotonin (5-HT)1B receptors in the mechanism of action of selective serotonin re-uptake inhibitors (SSRI) was studied by using intracerebral in vivo microdialysis in conscious, freely moving wild-type and 5-HT1B receptor knockout (KO 5-HT1B) mice in order to compare the effects of chronic administration of paroxetine via osmotic minipumps (1 mg per kg per day for 14 days) on extracellular 5-HT levels ([5-HT]ext) in the medial prefrontal cortex and ventral hippocampus. Basal [5-HT]ext values in the medial prefrontal cortex and ventral hippocampus, approximately 20 h after removing the minipump, were not altered by chronic paroxetine treatment in both genotypes. On day 15, in the ventral hippocampus, an acute paroxetine challenge (1 mg/kg i.p.) induced a larger increase in [5-HT]ext in saline-pretreated mutant than in wild-type mice. This difference between the two genotypes in the effect of the paroxetine challenge persisted following chronic paroxetine treatment. Conversely, in the medial prefrontal cortex, the paroxetine challenge increased [5-HT]ext similarly in saline-pretreated mice of both genotypes. Such a challenge produced a further increase in cortical [5-HT]ext compared with that in saline-pretreated groups of both genotypes, but no differences were found between genotypes following chronic treatment. To avoid the interaction with raphe 5-HT1A autoreceptors, 1 micro m paroxetine was perfused locally through the dialysis probe implanted in the ventral hippocampus; similar increases in hippocampal [5-HT]ext were found in acutely or chronically treated wild-type mice. Systemic administration of the mixed 5-HT1B/1D receptor antagonist GR 127935 (4 mg/kg) in chronically treated wild-type mice potentiated the effect of a paroxetine challenge dose on [5-HT]ext in the ventral hippocampus, whereas systemic administration of the selective 5-HT1A receptor antagonist WAY 100635 did not. By using the zero net flux method of quantitative microdialysis in the medial prefrontal cortex and ventral hippocampus of wild-type and KO 5-HT1B mice, we found that basal [5-HT]ext and the extraction fraction of 5-HT were similar in the medial prefrontal cortex and ventral hippocampus of both genotypes, suggesting that no compensatory response to the constitutive deletion of the 5-HT1B receptor involving changes in 5-HT uptake capacity occurred in vivo. As steady-state brain concentrations of paroxetine at day 14 were similar in both genotypes, it is unlikely that differences in the effects of a paroxetine challenge on hippocampal [5-HT]ext are due to alterations of the drug's pharmacokinetic properties in mutants. These data suggest that there are differences between the ventral hippocampus and medial prefrontal cortex in activation of terminal 5-HT1B autoreceptors and their role in regulating dialysate 5-HT levels. These presynaptic receptors retain their capacity to limit 5-HT release mainly in the ventral hippocampus following chronic paroxetine treatment in mice.

Modified costochondral graft osteotomy in hemifacial microsomia

Hemifacial microsomia is the second most common facial clefting condition after cleft lip and palate. The deformity affects the skeleton and soft tissues in the temporal region of the affected side, although the degree of involvement is markedly variable. We describe a modification of surgical technique in a skeletally mature case who had previously undergone mandibular reconstruction with a costochondral graft.

Blindness and severe visual impairment in facial fractures: an 11 year review

We present an 11 year review of facial fractures treated in the Australian Craniofacial Unit and the Department of Plastic and Reconstructive Surgery at the Royal Adelaide Hospital, specifically looking at those fractures in adults that resulted in blindness or severe visual impairment. During the period 1989-2000, a total of 2516 patients with facial fractures were treated operatively. From our facial-fracture database, 317 patients were identified as having an ophthalmological complication on presentation. Of these, 19 had severe visual impairment or blindness. The exact fracture pattern and craniofacial disruption score were recorded for each of these 19 cases using the Cooter-David facial-fracture scoring system. Laterally directed forces are implied as major causative factors in these injuries. Recommendations are made based on these findings.

Oblique facial clefting associated with unicoronal synostosis

Oblique facial clefts are said to account for 0.25% of all clefts. Craniosynostosis is not known to be associated with oblique facial clefting, although craniofrontonasal dysplasia is well described. Craniosynostosis and oblique facial clefting presenting together in the same patient is a rare event. We present such a case, and detail the treatment plan to allow simultaneous correction of both deformities.

Are there gender differences in the temperature profile of mice after acute antidepressant administration and exposure to two animal models of depression?

Numerous studies have reported gender differences in the rates of depression in humans, but few behavioural observations of antidepressant drug effects have been investigated in female mice. The forced swimming test (FST) is widely used as a predictor of antidepressant activity in rodents, as is the tail suspension test (TST), where immobility is objectively measured and in this last test, no hypothermia is induced by immersion in cold water. The present study investigated gender differences in the temperature profile of mice after acute antidepressant administration (imipramine and paroxetine) and exposure to two animal models of depression. Imipramine and paroxetine were active at 32 mg/kg in male mice in the FST, whereas they were active at 8, 16 and 32 mg/kg in female mice. In the TST, for both antidepressants immobility duration was reduced at a dose of 16 and 32 mg/kg in male mice and at 32 mg/kg in female mice. No significant difference was observed between male and female mice for immobility duration. Imipramine administration, but not paroxetine, decreased the temperature at the higher dose (32 mg/kg) in male and female mice in the FST. The body temperature was reduced in male and female mice for all treatment groups after FST challenge. Imipramine (16 and 32 mg/kg in male and 32 mg/kg in female mice), paroxetine (4, 16 and 32 mg/kg in male and 4 to 32 mg/kg in female mice) attenuated the reduction in temperature due to the FST. In the TST, imipramine tends to decrease the temperature in male and female mice, even though only imipramine at a dose of 32 mg/kg in female mice significantly decreases the temperature. Paroxetine had no effect on temperature. The TST enhanced the body temperature in male and female mice. In mice, there was no difference between the sexes after imipramine or paroxetine administration in the FST and TST. Both tests can be used to predict the activity of antidepressants as the decrease or enhancement of temperature is not correlated with a reduction in immobility duration.

Comparison of antidepressant activity in 4- and 40-week-old male mice in the forced swimming test: involvement of 5-HT1A and 5-HT1B receptors in old mice

RATIONALE

A recent study suggested that selective serotonin reuptake inhibitors were inactive in 40-week-old male mice in the mouse forced swimming test, possibly because of alteration of 5-HT1 receptors.

OBJECTIVES

The present study was aimed at investigating the action of various antidepressant drugs in 4- and 40-week-old male mice using the mouse forced swimming test and determining the involvement of 5-HT1A and 5-HT1B receptors mediating the effects.

METHODS

Different classes of antidepressants [imipramine (tricyclic), maprotiline (noradrenline reuptake inhibitor), venlafaxine (mixed serotonin and noradrenaline reuptake inhibitors), fluvoxamine and sertraline (selective serotonin reuptake inhibitor)] were tested in the same randomised experimental session, alone and in combination with 5-HT1A and 5-HT1B receptor agonists [buspirone (partial 5-HT1A agonist), anpirtoline (5-HT1B agonist)] in the mouse forced swimming test.

RESULTS

All antidepressants were found to be active in the mouse forced swimming test in 4-week-old mice and 40-week-old mice, with the exception of fluvoxamine in the 40-week-old mice. The anti-immobility effect after antidepressant administration was higher in 4-week-old male mice than in 40-week-old male mice. Venlafaxine is the most active antidepressant drug in 40-week-old mice. Prior administration of buspirone (0.06 mg/kg, i.p.) or anpirtoline (1 mg/kg, i.p.) enhanced the antidepressant-like effects in 4-week-old mice (except in the case of sertraline, 8 mg/kg). In elderly mice, only prior administration of buspirone enhanced the antidepressant-like effects of fluvoxamine. A neurochemical study showed that significantly higher serotonin and dopamine concentrations were found in 40-week-old control mice brains than 4-week-old control mice brains but that the noradrenaline concentration is higher in 4-week-old mice.

CONCLUSION

Tricyclic, noradrenaline reuptake inhibitors and serotonin reuptake inhibitors are more active in 4-week-old mice than 40-week-old mice. Our results suggested that 5-HT1B receptors may be more altered than 5-HT1A receptors in 40-week-old mice.

Occipital plagiocephaly

The diagnosis of occipital plagiocephaly has remained a complex and controversial issue in the field of craniofacial surgery. Over the past 30 years, numerous studies have been published describing the management and treatment for 'posterior plagiocephaly', 'plagiocephaly without synostosis', 'deformational plagiocephaly' and 'occipital plagiocephaly', with surgical 'correction' being chosen as the primary modality of treatment irrespective of the patency status of the lambdoid sutures. Two hundred and four patients with unilateral occipital plagiocephaly have been seen at the Australian Craniofacial Unit over the past 16 years. Each patient was evaluated by a craniofacial surgeon, paediatric neurosurgeon and paediatric geneticist. All children underwent plain radiographs of the skull to define the sutural anatomy. In those patients where the sutural anatomy was equivocal, 2-D and 3-D CT scans were performed. Only two of the 204 patients (approximately 1%) manifested the clinical, radiographic and pathological features of true unilambdoid synostosis. There was radiographic evidence of sutural fusion on plain films, 2-D and 3-D CT scans. Pathology specimens showed bony sutural fusion. Two hundred and two patients presented with unilateral occipital deformities and patent sutures on radiography. These patients with occipital plagiocephaly in the absence of true synostosis were initially managed conservatively (head positioning, and physiotherapy in those patients with torticollis). Those patients who underwent surgical correction in infancy (21/204) included patients with severe plagiocephaly not responding to conservative therapy (19/204) and the two patients with true unilambdoid synostosis (2/204).One hundred and ninety-one of the total patients (94%) were noted by their parents to have acceptable improvement in their head shape. Thirteen patients were seen within the past year and are too early to assess. Two surgical patients (one fronto-orbital advancement, one occipital craniectomy) and one patient followed conservatively were judged by their parents to be without notable improvement. In our series it is apparent that the majority of cases of occipital plagiocephaly are not secondary to true synostosis and can be managed by conservative positional measures.

CT-determined intracranial volume for a normal population

Intracranial volume comparisons of patients with craniosynostosis and normal have been contrary to expectations, leading to questioning of the validity of the current normal reference material. Computed tomography-determined intracranial volume is presented for a white normal population. Specifically, intracranial volumes for 157 subjects (82 female and 75 male) were measured from computed tomography data using the Cavalieri estimator: volume determination was based on measuring the area in each computed tomography section. Monomolecular and Gompertz models were applied to find curves of best fit to the intracranial volume as a function of the age. The best fit was obtained using the monomolecular model when the response variable was the logarithmically transformed intracranial volume, and the independent variable was the logarithm of the age from conception. For example, the mean (standard deviation) for male subjects at 1 year and 20 years were 1,125.6 (89.6) ml and 1,472.9 (117.2) ml, respectively, and for female subjects 1,024.9 (84.0) ml and 1,321.7 (108.3) ml, respectively. Although the shape and rate of increase of the female and male curves is similar, the female mean is 1.3 standard deviations below the male mean at 20 years. These curves were compared with the commonly referenced curves of Blinkov (1941), Lichtenberg (1960), and Dekaban (1977). Our male curve is substantially higher than these curves in the age range 8 months to 4 years. Our female curve, however, is approximately 1 standard deviation below Lichtenberg's curve from birth to 7 months. There are then only minor differences between our female curve and Lichtenberg's curve until his curve crosses ours at 41 months, where they significantly diverge from approximately 4.5 years. Our curves indicate that 95% of the final intracranial volume has been attained by 42 months for girls and 46 months for boys.

Outcome measurement of the treatment of maxillary fractures: a prospective analysis of 100 consecutive cases

We performed a prospective study of 100 consecutive patients presenting to our unit with complex maxillary fractures. Fracture severity was assessed according to the alpha-numeric scoring system of Cooter and David and correlated with outcome. Regional maxillary and total fracture scores demonstrated a positive correlation with complication rates, with correlation coefficients of 0.89 and 0.98 respectively. Ocular and orbital complications were most commonly seen with these complex injuries, but occlusal problems were much less common. Despite close consultant-led supervision in a specialised centre, these injuries frequently result in long term problems.

Tissue expansion in the reconstruction of Tessier craniofacial clefts: a series of 17 patients

Tessier craniofacial clefts are among the most surgically challenging examples of craniofacial dysmorphology. These clefts are characterized by hypoplasia of soft-tissue and skeletal elements throughout the three-dimensional extent of the cleft. Whereas bone grafting and craniofacial osteotomies have been successful toward correcting the underlying skeletal abnormalities, the ultimate success of these reconstructions has been limited by the deficiency of skin and soft tissue. This deficiency demands reconstruction ideally with tissue of like texture, consistency, and, especially in the face, color. Craniofacial tissue expansion was used toward reconstructing these facial clefts with like-quality tissue, allowing for tension-free reconstruction after osteotomy and bone grafting. Seventeen patients with Tessier craniofacial clefts underwent preoperative craniofacial soft-tissue expansion in the surgical management of their clefts. Tissue expansion was used in the primary correction of facial clefts in eight patients, with nine patients undergoing expansion before secondary surgery. In this series, tissue expansion has evolved as an important element in overcoming the skin and soft-tissue deficiency associated with these clefts, allowing for tension-free closure and improved aesthetic results in these surgically challenging patients.

Computer generated mandibular model: surgical role

A life-size nylon model of a traumatized mandible was produced from CT scan data by the process of laser sintering. The model was used for pre-operative planning and for production of surgical aids in order to facilitate the restoration of a large bony defect. Vascularized iliac crest bone was harvested, titanium implants placed and the bone then grafted to the mandible.

Computer tomography determined intracranial volume of infants with deformational plagiocephaly: a useful "normal"?

Over the last 10 years, children with deformational (nonsynostotic) plagiocephaly have undergone computed tomography scans using the same protocols as children with lambdoid craniosynostosis because of their similarly distorted head shapes. These children are believed to have normal intracranial volume. Given the recent questioning of what is the normal range of intracranial volume in human populations, the authors have undertaken a comparison of the intracranial volume of children with deformational plagiocephaly and Lichtenberg's normal population (Lichtenberg R. Radiographie du crane de 226 enfants normaux de la naissance a 8 ans: Impressions digitiformes, capacite, angles et indices [thesis]. Paris: University of Paris, 1960). The intracranial volume was determined for 20 females and 46 males with deformational plagiocepahly ranging in age from 2.5 to 20.7 months using computed tomography scan data. Although no significant differences were found for the females, the authors found that the intracranial volume of the males with deformational plagiocephaly were significantly larger than Lichtenberg's population. The authors conclude that this is because Lichtenberg's data do not adequately reflect the normal range of intracranial volume for males ranging in age from 2.5 to 20.7 months, rather than gender differences associated with deformational plagiocephaly. Further, until a more suitable normal becomes available, the deformational (nonsynostotic) plagiocephaly data could be used as substitute normal reference material in the measured age range for assessment of the intracranial volumes of children with craniosynostosis.

Nicotine-evoked nitric oxide release in the rat hippocampal slice

The effects of cholinergic agonists on nitric oxide (NO) release in hippocampal slices from male Sprague-Dawley rats were investigated using electrochemical recording procedures using Nafion and O-phenylenediamine-treated carbon fiber microelectrodes. These microelectrodes are highly selective for NO versus other interferents. Acetylcholine (Ach) with neostigmine, or nicotine was delivered by pressure ejection from pipettes placed within 300 microm of the NO sensors. Both Ach and nicotine produced NO signals ranging from 0.04 to 2.14 microM in the CA1, CA3, and dentate gyrus of the rat hippocampus that lasted for 2-5 min. The Ach responses were not antagonized by the muscarinic antagonist atropine. However, nicotine-evoked responses were partially antagonized by alpha-bungarotoxin, a finding consistent with alpha7-nicotinic cholinergic receptors being involved with the effects of nicotine. These data support the hypothesis that nicotine is capable of evoking long lasting NO release in the hippocampus.

In vivo electrochemical studies of dopamine clearance in subregions of rat nucleus accumbens: differential properties of the core and shell

The dopamine (DA) uptake/clearance properties of the DA transporter (DAT) in the core and shell of the nucleus accumbens were measured using in vivo electrochemical recordings. Calibrated amounts of a DA solution were pressure-ejected from a micropipette/electrode assembly placed in the core or shell of the nucleus accumbens in anesthetized male Fischer 344 rats. Initial studies in the two brain regions revealed that the core and shell have different DA clearance properties as measured by the extracellular DA signal amplitudes, clearance times, and clearance rates. Although the same number of picomoles of DA were applied, DA clearance signals recorded in shell had significantly greater amplitudes but faster clearance rates than those recorded in the core. Systemic administration of 20 mg/kg cocaine, a monoamine transporter inhibitor, greatly increased the signal amplitude from the locally applied DA in both the core and shell. Signal amplitudes were increased to a greater extent in the shell, compared with the core, after cocaine administration. However, cocaine affected the clearance time of DA only in the core and the DA clearance rate only in the shell. Taken together with previously reported data, these studies further support differential activity of the DAT in the core versus shell subregions of the nucleus accumbens. In addition, these data indicate that DATs are more sensitive to the effects of psychomotor stimulants, such as cocaine, in the shell of the nucleus accumbens.

Transcranial correction of orbital neurofibromatosis

Neurofibromatosis is a systemic disease that often produces striking disfigurement. Orbital manifestations are common and include sphenoid dysplasia with or without infiltration of the periorbital soft tissues. The resultant deficiency of the posterolateral orbital wall may lead to protrusion of the temporal lobe into the orbit, displacement of the globe, and pulsatile exophthalmos. Treatment at our unit has consisted of transcranial orbital reconstruction with bone grafts and periorbital soft-tissue correction. Observation of complete bone graft resorption in one patient prompted an assessment of the Australian Craniofacial Unit's experience with particular attention paid to the stability of operative correction. Of 36 patients with head and neck neurofibromatosis treated during the period from 1981 to 1995, 14 patients underwent transcranial correction of orbital deformities secondary to sphenoid dysplasia. The treatment and outcomes of this transcranial group are reviewed. The most notable finding was that of recurrent globe pulsation in four patients following initial resolution. Computed tomography scans have documented partial to complete bone graft resorption in three of these patients. Titanium mesh is now being utilized to provide a more durable reconstruction.