Marjan Vandersteen

Anatomy and surgery of the infected dermal sinus of the lower spine

ObjectCases of infected dermal sinus are scarce and detailed surgical anatomical descriptions are hardly found in literature. The clinical, radiological, and surgical findings in four cases of an infected dermal sinus located at the lower spine are presented to elucidate the pathological anatomical configuration.Clinical materialThe first case showed two dermal sinuses with a parallel course extra- and intradurally, ending in a confluence of cavities connected to the conus. In this case, as well as in the fourth case, the signs and symptoms were those of meningitis. The second case presented with meningitis and a subdural empyema, while the third case presented with an intradermoid–intramedullary abscess at the junction between the DS and the conus. This child probably showed signs and symptoms of conus involvement as early as during pregnancy.ConclusionThe anatomy of the nervous elements in this congenital anomaly is heavily disturbed, more particularly in case of infection, due to extensive arachnoidal scarring. The latter renders dissection laborious and recognition of anatomical details difficult, resulting in complete excision of a dermal sinus in less than half of the cases. Despite their variability in presentation, most cases of an infected dermal sinus show similar characteristic features.

The microanatomical environment of the subthalamic nucleus

High-frequency stimulation of the subthalamic nucleus (STN) is a widely performed method to treat advanced Parkinson disease. Due to the limitations of current imaging techniques, the 3D microanatomy of the STN and its surrounding structures in the mesencephalon are not well known. Using images they obtained using a 9.4-tesla magnetic resonance (MR) imaging unit, the authors developed a 3D reconstruction of the STN and its immediate surroundings. During the postmortem investigation of a human brain, a sample of tissue in the area around the STN was isolated. This brain tissue was scanned in the three orthogonal planes at 1-mm slice thickness. The images generated were compared with photographs of conventionally stained brain tissue slices in different neuroanatomical books, and a 3D reconstruction was made. High-field MR imaging is an appropriate method for visualizing the microanatomy of the STN and its surroundings. The images allow an optimal analysis of the microenvironment of the STN in the three orthogonal planes and can be used for 3D reconstructions of this area with possible clinical applications in the future.

The Arnold-Chiari type II malformation at midgestation.

The Arnold-Chiari malformation type II (ACMII) is reported to be reversible after closure of a myelomeningocele at midgestation. To elucidate the developmental state of the ACMII malformation at the approximate time fetal surgery is performed, the ACMII of a 20-week human fetus was investigated in vitro using high-field magnetic resonance microscopy at 9.4 T and compared with the hindbrain of a neurologically intact fetus of the same gestational age. Up to 20 weeks of gestation, the developmental failures caused by the early embryonic herniation of the posterior fossa contents are the dominant feature of fetal ACMII, but after 20 weeks, the accelerated and disproportionate growth of the cerebellum dominates. As midgestational surgery stops the leakage of cerebrospinal fluid, the posterior fossa will expand in time to allow further normal growth of both the cerebellum and brain stem. Some early developmental anomalies already present in the primitive rhombencephalon due to early embryonic hindbrain herniation as well as some intra-axial anomalies are probably not reversible.

Junctional zone thickness in young nulliparous women according to menstrual cycle and hormonal contraception use

This prospective study aims to determine the optimal menstrual phase and uterine location to detect the thickest junctional zone by magnetic resonance imaging (MRI). Healthy nulliparous women were subdivided according to their use of hormonal contraception. Each women was investigated three times during their menstrual cycle. Eighteen nulliparous non-users and 29 nulliparous users of hormonal contraception (mean age 26.4 and 25.8 years, respectively) underwent a pelvic MRI (1.5T) examination during the follicular, ovulatory and luteal phase. The junctional zone thickness was measured at six locations in the uterine wall. A significantly thinner junctional zone was observed at the anterior and posterior wall of the midcorpus (P = 0.01 and P = 0.004 respectively) and fundus (P = 0.009 and P = 0.023 respectively), in the contraception users compared with the non-users. No differences in junctional zone thickness were noticed between the menstrual phases and the uterine wall locations. The ratio of junctional zone versus total myometrial thickness was also different between both groups and between the assessed uterine locations. To conclude, any phase in the menstrual cycle and location within the uterine wall was validated to determine the junctional zone thickness on MRI, although the fundal location is preferred.

Anaesthesia of the inferior alveolar and lingual nerves following subcondylar fractures of the mandible

A retrospective chart review of 387 patients with condylar and subcondylar fractures revealed 2 cases of inferior alveolar nerve (IAN) and lingual nerve (LN) anaesthesia following the subcondylar fracture. Only 5 cases have been reported previously. The mechanism of action remains unknown but a review of the literature and an analysis of 120 dry human skulls supported the hypothesis that compression of the mandibular nerve at a high level, close to the foramen ovale, could cause anaesthesia. This complication is rare, because it requires compression at a particular angle. The antero-median angulation of the condyle must be close to the foramen ovale, and the fracture must be a unilaterally displaced fracture. The presence of an enlarged lateral pterygoid plate appeared to enhance the risk of compression. The IAN and LN anaesthesia could be resolved after open reduction of the fracture and IAN and LN anaesthesia constitute a strict indication for an early open fracture reduction.

Perfusion of the uterine junctional zone in nulliparous and primiparous women assessed by DCE-MRI as a function of menstrual cycle and hormonal contraception.

PURPOSE To evaluate the perfusion parameters of inner and outer myometrium in healthy nulliparous and primiparous women who are and who are not currently using hormonal contraceptives by means of dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). MATERIAL AND METHODS We performed pelvic 1.5T DCE-MRI on 98 women: 18 nulliparous non-users, 30 nulliparous users, 12 primiparous non-users and 38 primiparous users of hormonal contraception (mean age respectively 26.4, 25.8, 30.23 and 28.18years). The nulliparous non-users underwent DCE-MRI investigations during their follicular, ovulatory and luteal phase. Perfusion parameters (iAUC/volume, Ktrans, Kep and Ve) were assessed in the anterior and posterior junctional zone (JZ), outer myometrium and cervix. RESULTS In nulliparous non-users, the mean Ktrans and iAUC/volume showed a decrease from follicular to luteal phase (0.82 vs 0.55min-1 for Ktrans, p=0/027 and 1.28 vs 0.68 for iAUC/volume, p<0.001). The anterior JZ demonstrated lower Ktrans (p=0.050) and higher Kep (p=0.012), in nulliparous non-users, lower Ktrans in nulliparous users (p<0.001) and lower Ve in primiparous users (p=0.012) than the anterior outer myometrium. Ktrans at the anterior and posterior JZ wall in nulliparous users was lower than in non-users (p=0.001 and p=0.013) and Ve at the anterior JZ wall in primiparous users was lower than in non-users (p=0.044). CONCLUSION This study provides data on normal perfusion parameters of inner and outer myometrium, which may be potentially useful in assisted reproductive therapy.

Uterine junctional zone thickness in infertile women evaluated by MRI

To prospectively evaluate and compare the junctional zone (JZ) and outer myometrial thickness in infertile and healthy nulliparous women at different locations in the uterine wall during the menstrual cycle by magnetic resonance imaging (MRI).