Anterior transpetrosal resection of the lower ventral pontine cavernous malformation: A technical case report with operative video

Background

Surgical treatment of pontine cavernous malformations (CMs) is challenging due to the anatomical difficulties and potential risks involved. We successfully applied an anterior transpetrosal approach (ATPA) to remove a lower ventral pontine CM, and herein we discuss the outline of our procedure accompanied by a surgical video.

Case Description

A 50-year-old woman presenting with progressively worsening diplopia was urgently admitted to our hospital. Preoperative images showed a lower ventral pontine CM compressing the corticospinal tract posteriorly. Considering the location of the CM, we determined that an ATPA was the appropriate approach to achieve a more anterolateral trajectory. We performed extradural anteromedial petrosectomy and penetrated the brainstem from the point just below the anterior inferior cerebellar artery and above the root exit zone of the abducens nerve, which might be located in the somewhat lowest border of actual maneuverability in the ATPA. Maneuverability through this corridor was sufficient without hindering and darkening the high magnification microscopic view, as demonstrated in our surgical video.

Conclusion

This report demonstrates surgical treatment of a lower ventral pontine CM using the ATPA. The surgical video we present provides information that is useful for understanding this technique's maneuverability and working window.

Management of brain metastasis from eccrine porocarcinoma: illustrative case

BACKGROUND

Eccrine porocarcinoma (EP) is a rare malignant skin neoplasm, and there are still many unknowns regarding its natural history and treatment. Due to its scarcity, associated brain metastasis is a far rarer condition.

OBSERVATIONS

A 71-year-old-woman with a history of EP was diagnosed with brain metastasis. In her clinical course, the patient underwent tumor removal surgery twice and Gamma Knife radiosurgery (GKRS) four times. The tumor showed a good response to radiotherapy. The histopathological findings of the brain tumor were consistent with those of the primary skin tumor.

LESSONS

There are only a few case reports referring to the detailed treatment, especially with GKRS, of brain metastasis from EP. Few reports have presented a detailed histopathological comparison between the primary skin lesion and the metastatic brain lesion. Herein, the authors have described the clinical course, histological features, and results of multidisciplinary treatment for brain metastasis of EP.

[Catamenial pneumothorax due to diaphragmatic endometriosis confirmed by histological examination; report of a case]

We reported a case of catamenial pneumothorax caused by diaphragmatic endometriosis that was histologically confirmed. A 49-year-old female who had recurrent chest pain and cough appearing on the day preceding each menstruation from 5 years ago. These episode suggested catamenial pneumothorax. Thoracotomy revealed the characteristic appearances of catamenial pneumothorax such as blueberry spots and multiple small holes on the central tendon of the right diaphragm. But there were no lesions on the visceral pleura of the lung. Partial resection of the diaphragm including these lesions were performed. Histological examination showing positive for estrogen receptor and progesterone receptor confirmed the presence of endometrial tissue on the diaphragm. The patient has been well controlled by therapy with gonadotropin releasing hormone, without recurrence of catamenial pneumothorax.

[Primary clear cell adenocarcinoma of the lung with endobronchial polypoid growth: report of a case]

Clear cell adenocarcinoma with endobronchial polypoid growth of the lung is extremely rare. A 65-year-old male with hemosputum was found to have an abnormal shadow in the hilum of the left lung. Computed tomography of the chest revealed that a heterogeneous mass occupied the lumen extending outside the upper lobe bronchus of the left lung. By biopsy, the tumor was determined to be adenocarcinoma. The patient underwent left pneumonectomy with mediastinal lymph node dissection. Macroscopically, the tumor showed a polypoid growth along with the bronchial tree. Microscopically, most of the tumor was composed of large clear cells with partial glandular formation, indicating the tumor to be adenocarcinoma Lymph node metastasis was seen in #5 and #12u. The lung cancer was diagnosed as clear cell adenocarcinoma with endobronchial polypoid growth.

Intracortical inhibition of the motor cortex in Segawa disease (DYT5)

BACKGROUND

Segawa disease (autosomal dominant guanosine triphosphate cyclohydrolase I [GTP-I] deficiency, DYT5) is a hereditary dopa-responsive generalized dystonia.

OBJECTIVE

To investigate the pathophysiologic mechanisms for dystonia in Segawa disease, we studied intracortical inhibition of the primary motor cortex in patients with Segawa disease.

METHODS

We studied 9 patients with Segawa disease (8 genetically confirmed patients and 1 with abnormally low GTP-I activity) and 12 age-matched normal control subjects. We studied the active motor threshold (AMT) using single pulse transcranial magnetic stimulation (TMS) and the short-interval intracortical inhibition (SICI) of the motor cortex using the previously reported paired pulse TMS method. Responses were recorded from the first dorsal interosseous (FDI) and tibialis anterior (TA) muscles.

RESULTS

The AMT was not significantly different between the patients and normal subjects. For both studied muscles, in Segawa disease, normal amount of SICI was evoked at interstimulus intervals (ISIs) of 1 to 4 msec even though they had dystonia in those muscles.

CONCLUSION

Normal SICI of the motor cortex in Segawa disease stands in remarkable contrast to the previously reported reduction of SICI in focal dystonia. This suggests that the gamma-aminobutyric acid A system of the motor cortex is intact in Segawa disease. The pathophysiologic mechanisms for dystonia must be partly different between Segawa disease and focal dystonia.

[Interesting pulmonary metastasis from spindle cell carcinoma of the breast]

We experienced a case of interesting pulmonary metastasis from spindle cell carcinoma of the breast. A 68-year-old female who had undergone a radical mastectomy 32 months earlier was admitted to our hospital for the pulmonary tumor in the left S10 in January 2005. Pathological study of the breast tumor revealed mixture of carcinomatous portion and sarcomatoid portion with spindle cells. Because of the presence of transitional areas from one portion to the other, the tumor was diagnosed as spindle cell carcinoma of the breast. Partial resection of the left lower lobe was performed. Pathological examination of the pulmonary tumor revealed that the tumor was composed of the component similar to carcinomatous element of the breast cancer. In June 2005, She was admitted to our hospital again for the pulmonary tumor in the right S7. Partial resection of the right lower lobe was performed. The tumor was composed of both carcinomatous and sarcomatoid elements. After operation, as she complained of epigastralgia, a gastroscopic examination was performed. It showed 2 white polypi of the stomach. The biopsy specimen of the polypi were composed of the tumor similar to the sarcomatoid element of the breast cancer. She died of widespread metastasis 43 months after mastectomy.

[Pleomorphic carcinoma of the lung rapidly developed multiple metastases after surgery]

Pleomorphic carcinoma of the lung is a type of carcinoma with spindle and/or giant cells with a poor diagnosis. A 73-year-old male was referred to our hospital because of the pulmonary tumor. Lung biopsy revealed that the tumor was poorly differentiated adenocarcinoma. No distant metastasis were observed by systemic examination. A right middle lobectomy with partial resection of the right upper lobe and lymph node dissection were performed, because the tumor (5.3 x 4.0 x 4.0 cm) was located in peripheral S' and invaded S3 via the interlobular space. Histological findings showed adenocarcinoma comprised of spindle cell components that reacted positively to epithelial membrane antigen (EMA) and no lymph node metastasis. Therefore, he was diagnosed with pleomorphic carcinoma of the lung, pT2N0M0, stage IB. But metastatic lesions newly appeared in the thoracic skin, the liver, the diaphragm, the bilateral adrenal glands, and the retroperitoneal space on the 30th postoperative day. He died of peritonitis and pleuritis on only 60 days after the operation.

Differential effects of sex steroid hormones on the expression of multiple first exons including a novel first exon of prolactin receptor gene in the rat liver

In addition to the known four alternative first exons E1(1), E1(2), E1(3) and E1(4) of the rat prolactin receptor (PRL-R) gene, a novel first exon, E1(5), was identified by cDNA cloning of the 5'-end region of PRL-R mRNA in the rat liver. Genomic fragments containing E1(5) and its 5'- or 3'-flanking regions were also cloned from rat kidney genomic DNA. A sequence search for E1(5) revealed that E1(5) is located 49 kb upstream of exon 2 of the PRL-R gene in rat chromosome 2q16. RT-PCR analysis revealed that E1(5) was preferentially expressed in the liver, brain and kidney. Expression profiles of E1(2)-, E1(3)- and E1(5)-PRL-R mRNAs in the liver of male and female rats at 5 days of age and those at 8 weeks of age were examined by RT-PCR. The levels of E1(2)-PRL-R mRNA in the female rat increased remarkably in rats at 8 weeks of age compared with those at 5 days of age, and the levels of E1(5)-PRL-R mRNA in the male rat decreased markedly at 8 weeks of age compared with those at 5 days of age. In the female rat, the levels of E1(2)-PRL-R mRNA at 8 weeks of age decreased with ovariectomy performed at 4 weeks of age and recovered with the administration of beta-oestradiol. On the contrary, the levels of E1(5)-PRL-R mRNA increased with ovariectomy and decreased with the oestrogen treatment. In the male rat liver, the levels of E1(2)-PRL-R mRNA at 8 weeks of age increased strikingly with castration performed at 4 weeks of age and became undetectable with the administration of testosterone. The levels of E1(5)-PRL-R mRNA increased slightly with castration and were restored by testosterone treatment. Removal of gonadal tissues and sex steroid hormone treatment had no effect on the expression levels of E1(3)-PRL-R mRNA in both female and male rat livers. These results indicated that the expression of the PRL-R gene in the liver is regulated by the differential effects of sex steroid hormones on the transcription of the multiple first exons including the novel one.

Heterogeneity in residual function of MeCP2 carrying missense mutations in the methyl CpG binding domain

Rett syndrome is a neurodevelopmental disorder with severe mental retardation caused by mutations in the MECP2 gene. Mutations in the MECP2 gene are also associated with other genetic disorders, including X linked mental retardation in males. Missense mutations identified so far are present primarily in the methyl CpG binding domain (MBD) of MECP2. Here, the functional significance of 28 MBD missense mutations identified in patients were analysed by transient expression of the mutant proteins in cultured cells. The effects of mutations were evaluated by analysis of the affinity of MeCP2 to pericentromeric heterochromatin in mouse L929 cells and on transcriptional repressive activity of MeCP2 in Drosophila SL2 cells. These analyses showed that approximately one-third (9/28) of MBD missense mutations showed strong impairment of MeCP2 function. The mutation of the R111 residue, which directly interacts with the methyl group of methyl cytosine, completely abolished MeCP2 function and mutations affecting beta-sheets and a hairpin loop have substantial functional consequences. In contrast, mutations that showed marginal or mild impairment of the function fell in unstructured regions with no DNA interaction. Since each of these mutations is known to be pathogenic, the mutations may indicate residues that are important for specific functions of MeCP2 in neurones.

Discussant--pathophysiologies of Rett syndrome

Studies on sleep parameters of Rett syndrome revealed hypoactivity of the noradrenaline (NA) and the serotonin (5HT) neuron in early infancy while preserving the function of the dopamine (DA) and the cholinergic neurons of the pons normally. The sleep-wake cycle remains in its development at the level of 4 months of age. Polysomnographies also showed a decrease of the function of the nigrostriatal (NS)-DA neuron in early childhood and suggested the development of receptor supersensitivity in late childhood. Neurohistochemical and neuroimaging (PET) studies revealed the hypofunction of the NS-DA neuron with receptor supersensitivity and of involvement of the cholinergic neurons to the cortical pathology, whereas no substantial pathological or histochemical abnormalities were observed in the NA and the 5HT neurons in the brainstem. The decrease of tyrosine hydroxylase without neurodegenerative changes observed in the substantia nigra of Rett syndrome had similarity to the pathology caused by excitotoxic lesion of the pedunculopontine nuclei (PPN) observed in an animal experiments. Clinically the grade of disability of locomotion was shown to correlate to the grade of the disabilities of language. These clinical manifestations were also correlated to the specific loci of the mutation in the methyl binding domain of the MECP2 gene. In rodents the axons of the brainstem 5HT neuron involved in the morphogenesis of the brain in the early developmental course disappear in neonates without apoptotic or degenerative changes in the neurons. This period corresponds to the first 1.5-2 years in humans. Thus, in Rett syndrome, the primary lesion appears in the brainstem NA and 5HT neurons which affects development of synaptogenesis of the cortex and also dysfunction of the PPN. The latter causes dysfunction of the DA neuron and the cholinergic neuron in the midbrain. The mutation of the MECP2 gene may cause early transcription of the genes which prune the axons of the aminergic neurons for the developmental morphogenesis of the central nervous system in early infancy.

R133C and R168X mutations in Japanese Rett syndrome patients: a caution for misdiagnosis

Rett syndrome is a neurodevelopmental disorder characterized by regression of motor and mental abilities in females after a period of normal development. The gene, MECP2, has been reported to be responsible for Rett syndrome. Here, we report the cases who were at first misdiagnosed as having homozygous mutations, and later corrected as heterozygous ones. We analyzed the MECP2 gene in three sporadic Japanese patients with Rett syndrome. Direct sequencing by using a primer set that was originally used in the first report of MECP2 mutation suggested two types of homozygous mutations (R133C and R168X). Previous reports of these mutations with heterozygous status, as well as the general nature of dominant inheritance in Rett syndrome females and lethality in hemizygous males, urged us to confirm the homozygosity of these mutations. By using a newly designed PCR primer, we found that these mutations actually occurred heterozygously in these patients. Sequence analyses of PCR products suggested that a C/T polymorphism found upstream of these mutations caused the preferential PCR amplification of the mutated alleles. These results recommend paying attention to biased PCR amplification that may lead to misjudgment of the result for mutational analysis of the MECP2 gene.

Functional analyses of MeCP2 mutations associated with Rett syndrome using transient expression systems

Rett syndrome, an X-linked neurodevelopmental disorder, is a major cause of mental retardation in females. Recent genetic analyses have revealed that mutations in the methyl-CpG-binding protein gene encoding MeCP2 are associated with Rett syndrome. In this study, we used transient expression systems to investigate the functional significance of mutations seen in patients with Rett syndrome. Missense mutations in the methyl-CpG-binding domain were analyzed by the transfection in mouse L929 cells and Drosophila SL2 cells. The L929 cells were utilized to investigate the effects of mutations on the affinity for heterochromatin, where methylated CpG dinucleotides are extremely enriched. The SL2 cells were utilized to analyze their effects on transcriptional repression activities. R106W and F155S mutations led to the substantial impairment of MeCP2 functions, showing the loss of accumulation of the mutated protein to mouse heterochromatin and the reduction of the transcriptional repressive activity in Drosophila SL2 cells. Intriguingly, the R133C mutant retained the functionality equivalent to MeCP2 in these analyses. On the other hand, the T158M mutation exhibited the intermediate level of the impairment of functions in both analyses. Thus, these functional assays are useful to evaluate the consequences of mutation in the methyl-CpG-binding domain of MeCP2 and provide an insight into the relationship between the genotype and the severity of Rett syndrome.

Pathophysiology of Rett syndrome from the stand point of clinical characteristics

In this report, we reviewed the characteristics of motor development and motor symptoms of Rett Syndrome (RTT) and demarcated the early and pathognomonic motor symptom which correlates to the impairment of the higher cortical function (HCF) assessed by the ability of language. It is suggested that failure of locomotion in late infancy is the primary and pathognomonic symptom. Thus, the impairment of the neurons or neuronal systems involving locomotion is suggested as the primary lesion in the pathophysiology of RTT not only for motor dysfunction but also for the failure in the development of language and cognitive function. On the other hand the neuronal systems involving the loss of purposeful hand use and the stereotyped hand movement, the most characteristic and diagnostic symptoms of RTT appearing in early childhood, are affected later or secondarily but induce further degradation of the HCF. Hypofunction of the aminergic neurons in the brainstem and midbrain is suggested as the cause of dysfunction of these neuronal systems, for those of locomotion, the noradrenarlin (NA) and/or the serotonin (5HT) neurons and for the stereotyped hand movement the dopamine (DA) neurons. The NA and/or the 5HT neurons in the brain stem may be involved primarily and may cause dysfunction of the midbrain DA neuron directly or indirectly through affecting the pedunculopontine nuclei.

Development of language in Rett syndrome

Ninety-nine cases of Rett syndrome (RTT) diagnosed clinically (age range 3 years 6 months to 29 years 9 months) were evaluated for the ability of language. The presence of meaningful words, vocabularies, and ages at the start and disappearance of speech were assessed. Phenotype/genotype correlation was evaluated in 22 cases in whom mutations of the genes of methyl-CpG-binding protein 2 (MECP2) existed. Fifty-five cases (55.5%) could speak some words, and of them eight cases (14.5%) spoke two-word sentences. No case had more than 40 words. The vocabularies were mainly bilabial words, known as the characteristics of the initial words in normal children. They began to utter a word between 12 and 48 months, and most of them (85.4%) before 20 months. Those who spoke two-word sentence(s) began to utter a word earlier (10.4+/-3.7 months) than others (17.1+/-9.8 months). Thirty-three cases lost their word(s) in 12-36 months. Among 22 gene-proven cases two cases with mutation of R133C and two cases with R294X had word(s), but another two cases with T158M had not. In RTT a delay in the neuronal systems involved in normal speech development was suggested and its severity seemed to depend on the loci of mutation.