Nucleus accumbens changes in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS), a representative example of motor neuron disease, is a progressive and fatal neurodegenerative disorder. The nucleus accumbens (NA) is the ventral striatum's main part and is considered as a modulator of the human brain's reward network. The purpose of this article is to review the current knowledge regarding NA changes in ALS patients. The NA involvement in ALS includes volumetric, cellular and molecular changes. There are recent imaging and pathological studies revealing NA atrophy in ALS, a finding which seems to be related to neuronal loss and protein deposition in this area. The clinical significance of NA atrophy in these patients is not currently fully understood. Perhaps it could be correlated with apathy, behavioral disturbances and cognitive impairment that ALS patients sometimes manifest.

Nucleus accumbens atrophy in Parkinson's disease (Mavridis' atrophy): 10 years later.

Parkinson's disease (PD) is a common neurodegenerative disorder associated with gray matter atrophy. The human nucleus accumbens (NA) is a major part of the ventral striatum and modulator of the reward network of the brain. It plays an important role in several cognitive and emotional functions. In patients with PD, dysfunction of this nucleus is correlated not only with movement disorders but also with various neuropsychological deficits and psychiatric symptoms. The human NA suffers atrophy in PD, which is called Mavridis' atrophy (MA), a well established characteristic of PD that was first described 10 years ago. The purpose of this article is to review the current knowledge regarding the clinical significance of MA. We currently know that it begins in early-stage PD patients, precedes clinical phenotype, and is part of the degeneration of the dopaminergic nigrostriatal system in these patients. MA has several clinical consequences. It is, more specifically, associated with the expression (and severity) of specific neuropsychiatric PD symptoms, namely cognitive impairment, apathy, disinhibition, and impulsive behavior, while its association with motor symptoms remains unclear. MA was recently suggested as a marker of global dysfunction in the mesocorticolimbic network. With new research data, new questions about MA emerge and further research is obviously necessary in order to effectively apply MA, as an imaging finding, to clinical practice.

Pediatric stereo-electroencephalography: effects of robot assistance and other variables on seizure outcome and complications.

OBJECTIVE: The safety of stereo-electroencephalography (SEEG) has been investigated; however, most studies have not differentiated pediatric and adult populations, which have different anatomy and physiology. The purpose of this study was to assess SEEG safety in the pediatric setting, focusing on surgical complications and the identification of patient and surgical risk factors, if any. The authors also aimed to determine whether robot assistance in SEEG was associated with a change in practice, surgical parameters, and clinical outcomes. METHODS: The authors retrospectively studied all SEEG cases performed in their department from December 2014 to March 2020. They analyzed both demographic and surgical variables and noted the types of surgery-related complications and their management. They also studied the clinical outcomes of a subset of the patients in relation to robot-assisted and non-robot-assisted SEEG. RESULTS: Sixty-three children had undergone 64 SEEG procedures. Girls were on average 3 years younger than the boys (mean age 11.1 vs 14.1 years, p < 0.01). The overall complication rate was 6.3%, and the complication rate for patients with left-sided electrodes was higher than that for patients with right-sided electrodes (11.1% vs 3.3%), although the difference between the two groups was not statistically significant. The duration of recording was positively correlated to the number of implanted electrodes (r = 0.296, p < 0.05). Robot assistance was associated with a higher number of implanted electrodes (mean 12.6 vs 7.6 electrodes, p < 0.0001). Robot-assisted implantations were more accurate, with a mean error of 1.51 mm at the target compared to 2.98 mm in nonrobot implantations (p < 0.001). Clinical outcomes were assessed in the first 32 patients treated (16 in the nonrobot group and 16 in the robot group), 23 of whom proceeded to further resective surgery. The children who had undergone robot-assisted SEEG had better eventual seizure control following subsequent epilepsy surgery. Of the children who had undergone resective epilepsy surgery, 42% (5/12) in the nonrobot group and 82% (9/11) in the robot group obtained an Engel class IA outcome at 1 year (χ2 = 3.885, p = 0.049). Based on Kaplan-Meier survival analysis, the robot group had a higher seizure-free rate than the nonrobot group at 30 months postoperation (7/11 vs 2/12, p = 0.063). Two complications, whose causes were attributed to the implantation and head-bandaging steps, required surgical intervention. All complications were either transient or reversible. CONCLUSIONS: This is the largest single-center, exclusively pediatric SEEG series that includes robot assistance so far. SEEG complications are uncommon and usually transient or treatable. Robot assistance enabled implantation of more electrodes and improved epilepsy surgery outcomes, as compared to those in the non-robot-assisted cases.

Pineal region tumors: pathophysiological mechanisms of presenting symptoms.

Pineal region tumors (PRTs) affect all ages, with a remarkable proportion of cases occurring in children. They are mainly classified into three categories, namely germ cell tumors (GCTs), pineal parenchymal tumors (PPTs), and other tumors such as gliomas and tumors of the surrounding structures. The purpose of this article is to review the current literature regarding pathophysiological mechanisms of the presenting clinical features of patients with PRT. The usual presentation of PRTs is the symptoms of obstructive hydrocephalus and intracranial hypertension, such as headache and vomiting. However, there is a remarkable spectrum of clinical findings that can be caused by such lesions. These include ophthalmologic and endocrinologic disturbances, motor and sensory abnormalities, and cognitive and psychiatric symptoms. The unique anatomic location of the pineal gland, which is close to many vital brain structures, is crucial for the explanation of most of those findings. In rare cases, manifestations of intracranial bleeding may be the presenting feature of a PRT. Tumor histology and patient's age can affect the clinical presentation. Hydrocephalus is the most common clinical syndrome of a PRT because of the location of the pineal gland. Presenting symptoms also include ophthalmologic, endocrinologic, motor, sensory, cognitive, and psychiatric symptoms. Clinicians should be aware of the initial symptoms of PRTs, including the misleading ones, in order to avoid delay in the diagnosis and management of these life-threatening lesions.

Nervous system involvement in Pfeiffer syndrome.

Pfeiffer syndrome (PS) is a rare autosomal dominant craniofacial disorder characterized by primary craniosynostosis, midface hypoplasia, and extremities' abnormalities including syndactyly. The purpose of this article was to review the current knowledge regarding how PS affects the nervous system. Methodologically, we conducted a systematic review of the existing literature concerning involvement of the nervous system in PS. Multiple-suture synostosis is common, and it is the premature fusion and abnormal growth of the facial skeleton's bones that cause the characteristic facial features of these patients. Brain abnormalities in PS can be primary or secondary. Primary anomalies are specific developmental brain defects including disorders of the white matter. Secondary anomalies are the result of skull deformity and include intracranial hypertension, hydrocephalus, and Chiari type I malformation. Spinal anomalies in PS patients include fusion of vertebrae, "butterfly" vertebra, and sacrococcygeal extension. Different features have been observed in different types of this syndrome. Cloverleaf skull deformity characterizes PS type II. The main neurological abnormalities are mental retardation, learning difficulties, and seizures. The tricky neurological examination in severely affected patients makes difficult the early diagnosis of neurological and neurosurgical complications. Prenatal diagnosis of PS is possible either molecularly or by sonography, and the differential diagnosis includes other craniosynostosis syndromes. Knowing how PS affects the nervous system is important, not only for understanding its pathogenesis and determining its prognosis but also for the guidance of decision-making in the various critical steps of its management. The latter necessitates an experienced multidisciplinary team.

Chyloperitoneum following open myelomeningocele repair: dealing with an extremely rare finding.

PURPOSE: Chyloperitoneum is an extremely rare finding following myelomeningocele (MMC) repair in neonates. We aimed to describe the characteristics of such a case and explore its clinical significance. CASE REPORT: A male baby born at term with open MMC and hydrocephalus underwent MMC repair surgery with rotational flaps on the first postnatal day. The procedure was uneventful. Three days later, he underwent a right ventriculoperitoneal shunt (VPS) insertion. On opening the peritoneum, a remarkable amount of yellowish opaque fluid was observed. Chyloperitoneum was suspected, but the VPS procedure was completed as planned. Biochemical analysis was consistent with that of chyle. DISCUSSION: Neonatal chylous ascites is a rare condition; hence, available data on pathophysiology and therapy in the literature are scarce. It is postulated that the MMC repair in neonates causes abdominal tautness, which leads to rupture of small lymphatics and raised intraportal pressure. The combination of these two processes results in extravasation of chyle from the gastrointestinal tract. Presence of chyloperitoneum is not a contraindication for VPS insertion. CONCLUSION: Chyloperitoneum is an extremely rare sequela of MMC repair in neonates. Pediatric neurosurgeons should be aware of it, especially when a VPS procedure is to follow a repair, in order to know how to deal with it and avoid unnecessary abandonment of the shunt.

Toxocariasis of the Nervous System.

PURPOSE: Toxocariasis is a helminthozoonosis caused by the infection of a human host by the larva of Toxocara spp., predominately involving Toxocara canis and Toxocara cati, which are common nematodes in dogs and cats, respectively. Human transmission occurs through contact with animals or by consumption of food contaminated with parasite's eggs. The purpose of this article is to review the current knowledge regarding human neurotoxocariasis. METHODS: We conducted a systematic review of the existing literature concerning toxocariasis of the nervous system. RESULTS: Clinical spectrum of human toxocariasis varies widely from a subclinical course to significant organ morbidity. Clinical course depends on parasitic load, the migration route of the larvae and host response. Human neurotoxocariasis is a relatively rare entity yet associated with severe sequelae. Manifestations include meningitis (usually eosinophilic), encephalitis, myelitis, cerebellar vasculitis, space-occupying lesion, behavioral abnormalities, and optic neuritis. Even though valid diagnostic criteria are lacking, neurotoxocariasis should be suspected in patients with neurologic symptoms and cerebrospinal fluid (CSF) pleocytosis with eosinophilia, positive serology for anti-Toxocara antibodies, in serum and/or CSF, sterile CSF and clinical improvement after antihelminthic treatment. Neurotoxocariasis is treated by benzimidazole components, most frequently albendazole, corticosteroids, or diethylcarbamazine. CONCLUSION: Parasite larvae migrate through tissues and are able to reach the nervous system causing neurotoxocariasis. Its clinical spectrum varies and includes myelitis, meningoencephalitis, brain abscess, and vasculitis. Neurotoxocariasis should always be suspected in patients with neurologic symptoms accompanied by eosinophilia in blood and/or CSF. Early diagnosis and treatment could prevent long-term neurologic impairment.

The Parieto-Occipital Artery Revisited: A Microsurgical Anatomic Study.

BACKGROUND: The parieto-occipital artery (PoA) is the terminal posterior cerebral artery branch, which typically runs in the parieto-occipital sulcus. Previous studies have highlighted variation in the PoA origin and branching pattern and their clinical implications. Nevertheless, PoA anastomoses have not been systematically investigated. The present study aimed to assess whether putative variation in PoA origin and its branching as well as anastomotic pattern is associated with differences in demographic/anthropometric variables. METHODS: In 15 cadaveric heads, PoA anatomic features were quantified and assessed in relation to demographic/anthropometric variables. RESULTS: The mean distance of PoA origin from the posterior limit of the splenium and the occipital pole (OP) is 3.1 and 53.1 mm, respectively. The latter is significantly longer in taller individuals. The PoA supplies a mean of 10.5 and 9.1 branches to the precuneus and cuneus, respectively. PoA anastomoses primarily involve the precuneal artery complex (PAc) and the calcarine artery. The analysis indicated significant, positive correlations between the distance of PoA origin from the OP and the number of PoA anastomoses and between the number of PoA precuneal and cuneal branches. CONCLUSIONS: Although the PoA invariably supplies the precuneus and almost always the cuneus, its direct contribution to the former seems inferior to PAc. Nevertheless, the PoA frequently shows putative collateral supply networks to the precuneus and cuneus via anastomoses with the PAc and calcarine artery, respectively. The distance between PoA origin and OP varies with an individual's height; the frequency of intrahemispheric PoA anastomoses varies with its site of origin.

How Deep Brain Stimulation of the Nucleus Accumbens Affects the Cingulate Gyrus and Vice Versa.

The nucleus accumbens (NA) and the cingulate gyrus (CG) are two vital limbic brain structures. They have attracted attention as deep brain stimulation (DBS) targets in the treatment of common refractory psychiatric illness. The primary purpose of this article was to review the current knowledge regarding the way that NA DBS affects the CG and vice versa. Methodologically, a thorough literature review was performed. According to the current literature, NA DBS modulates the function of several brain areas including the CG cortex. It specifically causes activation in the ipsilateral CG cortex and voltage-dependent reduction of its blood oxygenation. It also reverses anterior mid-CG cortex dysfunction and decreases metabolism in the subgenual CG. Moreover, NA DBS that induces mirth inhibits the function of the anterior CG cortex and enhances effective connectivity from anterior CG to the ventral striatum. On the other hand, although it is highly probable that CG DBS affects the NA, the exact nature of its effects remains unclear. Despite the increasing interest in psychiatric DBS, the available data on how NA DBS affects the CG and vice versa are restricted. This conclusion probably reflects the high complexity of the limbic circuits and necessitates further research.

Stereotactically Standard Areas: Applied Mathematics in the Service of Brain Targeting in Deep Brain Stimulation.

The concept of stereotactically standard areas (SSAs) within human brain nuclei belongs to the knowledge of the modern field of stereotactic brain microanatomy. These are areas resisting the individual variability of the nuclear location in stereotactic space. This paper summarizes the current knowledge regarding SSAs. A mathematical formula of SSAs was recently invented, allowing for their robust, reproducible, and accurate application to laboratory studies and clinical practice. Thus, SSAs open new doors for the application of stereotactic microanatomy to highly accurate brain targeting, which is mainly useful for minimally invasive neurosurgical procedures, such as deep brain stimulation.

Delayed Intraventricular Hemorrhage following a Ventriculoperitoneal Shunt Placement: Exploring the Surgical Anatomy of a Rare Complication.

Ventriculoperitoneal shunt (VPS) placement is one of the commoner neurosurgical procedures worldwide. The purpose of this article is to report a case of delayed intraventricular hemorrhage (IVH) following a VPS and to review the literature regarding anatomic factors that could potentially explain this rare complication. A 78-year-old man with normal pressure hydrocephalus, who underwent an uneventful right VPS placement, suffered from a catastrophic isolated IVH five days later. The reported cases of delayed intracerebral hemorrhage (ICH) following VPS are rare and those with IVH are even rarer. Potential factors of surgical anatomy that could cause delayed ICH/IVH following a VPS procedure include erosion of vasculature by catheter cannulation, multiple attempts at perforation, puncture of the choroid plexus, improper placement of the tubing within the brain parenchyma, VPS system revision, venous infarction, vascular malformations, head trauma, and brain tumors. Other causes include generalized convulsion, VPS system malfunction, increased intracranial or blood pressure, sudden intracranial hypotension, and bleeding disorders. According to the current literature, our case is the first reported delayed isolated IVH after a VPS placement so far. Neurosurgeons should be aware of the delayed ICH/IVH as a rare, potentially fatal complication of VPS, as well as of its risk factors.

Brain Activation During Singing: "Clef de Sol Activation" Is the "Concert" of the Human Brain.

Humans are the most complex singers in nature, and the human voice is thought by many to be the most beautiful musical instrument. Aside from spoken language, singing represents a second mode of acoustic communication in humans. The purpose of this review article is to explore the functional anatomy of the "singing" brain. Methodologically, the existing literature regarding activation of the human brain during singing was carefully reviewed, with emphasis on the anatomic localization of such activation. Relevant human studies are mainly neuroimaging studies, namely functional magnetic resonance imaging and positron emission tomography studies. Singing necessitates activation of several cortical, subcortical, cerebellar, and brainstem areas, served and coordinated by multiple neural networks. Functionally vital cortical areas of the frontal, parietal, and temporal lobes bilaterally participate in the brain's activation process during singing, confirming the latter's role in human communication. Perisylvian cortical activity of the right hemisphere seems to be the most crucial component of this activation. This also explains why aphasic patients due to left hemispheric lesions are able to sing but not speak the same words. The term clef de sol activation is proposed for this crucial perisylvian cortical activation due to the clef de sol shape of the topographical distribution of these cortical areas around the sylvian fissure. Further research is needed to explore the connectivity and sequence of how the human brain activates to sing.

The Microsurgical Anatomy of the Orbitofrontal Arteries.

OBJECTIVE: The orbitofrontal (or frontobasal) arteries (OFAs) are the medial (MOFA) and lateral (LOFA) orbitofrontal artery, branches of the anterior and middle cerebral artery, respectively. They supply the orbitofrontal cortex. The purpose of this microscopic cadaveric study was the detailed and precise anatomic identification of the OFAs along their course. METHODS: Twenty formalin-fixed, colored latex-injected cadaveric heads were studied with the aid of an operating microscope and microsurgical instrumentation. The anatomy of the OFAs was examined after removing the cerebrum from the cranial vault. Anatomic features of the MOFA and LOFA were investigated and assessed in relation to demographic and anthropometric variables. RESULTS: The MOFA supplies approximately 15 branches and LOFA almost 16 branches. The MOFA provides 1 branch to the olfactory bulb and 4 branches to the olfactory tract, and there are approximately 2 MOFA-LOFA anastomoses per hemisphere (novel finding). The MOFA origin is located approximately 7.9 mm anterior to the anterior communicating artery and 4.7 cm posterior to the anterior limit of the gyrus rectus. The LOFA origin is located approximately 11.1 mm from the middle cerebral artery bifurcation. Younger, shorter, and lighter individuals have more MOFA-LOFA anastomoses. Finally, the number of MOFA branches for the olfactory bulb is positively correlated with the number of MOFA branches for the olfactory tract, as well as with the number of MOFA-LOFA anastomoses. CONCLUSIONS: The present study provides a detailed description of the OFAs' microsurgical anatomy and can help neurosurgeons to easily identify, manipulate, and preserve these vessels during surgery.

Microsurgical Anatomy of the Precuneal Artery: Does It Really Exist? Clarifying an Ambiguous Vessel Under the Microscope.

BACKGROUND: The ambiguous term precuneal artery (PA) has several synonyms and anatomic definitions. OBJECTIVE: To examine the arteries of the precuneus and describe the PA and its branching pattern. We defined the PA as the principal arterial supplier of the precuneus. METHODS: Twenty formalin-fixed, colored latex-injected cadaveric heads were studied with the aid of an operating microscope and microsurgical instrumentation. After removal of the cerebrum from the cranial vault, we examined this vessel's anatomy. Anatomic features of the PA were investigated and assessed in relation to demographic and anthropometric variables. RESULTS: The PA was always a pericallosal artery branch and, more specifically, the superior internal parietal artery (SIPA) in 86.84%, the inferior internal parietal artery in 2.63%, and their common stem in 10.53% of specimens. Anastomosing interhemispheric branches between the PAs were present in 20% of cases. Compared with the right PA, the left anastomosed nearly 3 times more often with the ipsilateral posterior cerebral artery. The average distance of the PA's origin from the posterior limit of the splenium was shown to be 9.4 mm longer in elderly individuals compared with younger ones. CONCLUSION: The term PA complex (rather than PA) can better describe the principal arterial supplier of the precuneus, and the SIPA, inferior internal parietal artery, and their common stem were shown as the 3 contributing arteries, with the SIPA predominating. The average distance of the PA complex origin from the splenium's posterior limit shows significant variation with respect to age.