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Neurology(R) Neuroimmunology &... May 2021
Topics: Encephalitis; Humans; Magnetic Resonance Angiography; Magnetic Resonance Imaging; Middle Aged; Pons
PubMed: 33771838
DOI: 10.1212/NXI.0000000000000989 -
Irish Journal of Medical Science Apr 2024The diagnosis of central pontine hyperintensities on cranial magnetic resonance imaging has wide-spectrum clinical entities, and the pro-type diagnosis of these is... (Review)
Review
The diagnosis of central pontine hyperintensities on cranial magnetic resonance imaging has wide-spectrum clinical entities, and the pro-type diagnosis of these is central pontine myelinolysis. The rapid changes in extracellular environment due to an imbalance of electrolytes or metabolic or toxic stress to the myelin sheath can cause demyelination of white matter tracts in pons, which is why this situation could have different etiologies than just rapid sodium changes. Central pontine myelinolysis can be presented with different clinical scenarios from asymptomatic to death. Here, we present eight patients who had central pontine hyperintensities on radiological imaging but showed various clinical symptoms and different etiologies. The etiologies of these cases are hypertriglyceridemia, alcohol consumption, antidepressant usage, immunocompromised situations, uncontrolled diabetes mellitus, liver and kidney failure, electrolyte changes, and adrenal insufficiency. We aimed to take attention with this case series to the fact that not only fast correction of hyponatremia is the cause of central pontine myelinolysis, but also different etiologies could play a role in this situation, and making the central pontine myelinolysis diagnosis considering different diagnosis is very important.
Topics: Humans; Myelinolysis, Central Pontine; Pons; Hyponatremia; Magnetic Resonance Imaging; Liver
PubMed: 37831360
DOI: 10.1007/s11845-023-03538-9 -
The Journal of Comparative Neurology Sep 2014The medial prefrontal cortex (mPFC) of both rats and rabbits has been shown to support trace eyeblink conditioning, presumably by providing an input to the cerebellum...
The medial prefrontal cortex (mPFC) of both rats and rabbits has been shown to support trace eyeblink conditioning, presumably by providing an input to the cerebellum via the pons that bridges the temporal gap between conditioning stimuli. The pons of rats and rabbits, however, shows divergence in gross anatomical organization, leaving open the question of whether the topography of prefrontal inputs to the pons is similar in rats and rabbits. To investigate this question, we injected anterograde tracer into the mPFC of rats and rabbits to visualize and map in 3D the distribution of labeled terminals in the pons. Effective mPFC injections showed labeled axons in the ipsilateral descending pyramidal tract in both species. In rats, discrete clusters of densely labeled terminals were observed primarily in the rostromedial pons. Clusters of labeled terminals were also observed contralateral to mPFC injection sites in rats, appearing as a less dense "mirror-image" of ipsilateral labeling. In rabbits, mPFC labeled corticopontine terminals were absent in the rostral pons, and instead were restricted to the intermediate pons. The densest terminal fields were typically observed in association with the ipsilateral pyramidal tract as it descended ventromedially through the rabbit pons. No contralateral terminal labeling was observed for any injections made in the rabbit mPFC. The results suggest the possibility that mPFC inputs to the pons may be integrated with different sources of cortical inputs between rats and rabbits. The resulting implications for mPFC or pons manipulations for studies of trace eyeblink in each species are discussed.
Topics: Animals; Dextrans; Efferent Pathways; Fluorescent Dyes; Functional Laterality; Imaging, Three-Dimensional; Male; Microscopy, Fluorescence; Pons; Prefrontal Cortex; Rabbits; Rats; Rats, Sprague-Dawley; Species Specificity
PubMed: 24639247
DOI: 10.1002/cne.23566 -
World Neurosurgery Feb 2022The surgical management of lesions within or around the brainstem is usually associated with significant morbidity. Even though several safe entry zones have been...
The surgical management of lesions within or around the brainstem is usually associated with significant morbidity. Even though several safe entry zones have been described for brainstem lesions, especially cavernous malformations (CMs), their resection remains a challenge due to the convergence of highly functional nerve tracts and nuclei in this rather small structure. Moreover, the ventral location of some of these lesions usually calls for complex surgical approaches involving extensive bone drilling and significant manipulation of neurovascular structures. The expanded endoscopic endonasal approach has been subject to considerable advancements, widening the range of lesions accessible through this route. In this operative video, we describe the surgical nuances of an endoscopic endonasal transclival resection of a ventral pontine CM (Figures 1 and 2). A pedicled nasoseptal flap was harvested for reconstruction, gaining access to the sphenoid rostrum, which was resected. The sellar floor was removed to expose the middle third of the clivus, which was drilled out until posterior fossa dura mater was identified. A centered dural incision was performed to expose the ventral pons and basilar artery. Using image guidance, a limited pial incision over the most superficial aspect of the lesion allowed a prompt drainage of the hematoma and resection of the CM. The surgical cavity was directly inspected through the endoscope, confirming a complete resection. Reconstruction was carried out in a multilayered fashion. The patient presented a postoperative cerebrospinal fluid leak, which resolved with a lumbar drain. Neurologic status remained unchanged after surgery, with the patient displaying a favorable clinical outcome (Video 1).
Topics: Cranial Fossa, Posterior; Endoscopy; Humans; Nose; Pons; Skull Base
PubMed: 34740828
DOI: 10.1016/j.wneu.2021.10.142 -
Neurocirugia (English Edition) 2019To describe the anatomical measurements of the trigeminal nerve in patients with trigeminal neuralgia (TN) during Linac (linear accelerator)-based stereotactic...
PURPOSE
To describe the anatomical measurements of the trigeminal nerve in patients with trigeminal neuralgia (TN) during Linac (linear accelerator)-based stereotactic radiosurgery (SRS) simulation, targeting the root entry zone (REZ), with a 30% isodose line tangential to the pons, using 4-mm and 6-mm collimators.
METHODS
In this retrospective study, 53 TN patients, who underwent Fiesta sequence scanning prior to any treatment modality, were assessed. Bilateral measurements were obtained from the cisternal segment of the trigeminal nerve, the trigeminal-pontine angle, and the lateral width of the pontine cistern on the Fiesta MRI sequence. Linac-based SRS simulations were estimated with a radiation dosage of 90Gy to 30% isodose line tangential to the pons, with both 4- and 6-mm collimators. Distances from the calculated targets to the pons and the Gasserian ganglion were measured for later analysis. The statistical analysis was performed comparing the affected side against the unaffected side.
RESULTS
Right trigeminal nerve was affected in 36 patients (67.9%), and left one in 17 (32.1%) patients. The mean length of the trigeminal nerve was 9.8mm (range: 4.6-16.8mm) on the affected side, and 10.5mm (range: 5.6-18.4mm) on the unaffected side (p=.02). The mean trigeminal-pontine angle was 12.5° (range: 5.4° to 19.5°) on the affected side, and 10.2° (range: 5.0° to 30.5°) on the unaffected side (p=.01). In the simulations, the distances from the estimated targets to the pons and the Gasserian ganglion were not statistically different between sides. The variation of target-pons and target-ganglion distances was statistically significant on the affected side with the change of collimators (p<.001).
CONCLUSIONS
In this anatomical study, significant differences were identified in the length of the affected trigeminal nerve and trigeminal-pontine angle compared to the unaffected side in TN patients in Fiesta sequences prior to surgery or radiosurgery. Significant variation of the target location was found on the REZ between the 4- and 6-collimators during the Linac-based SRS simulations with the estimated radiation dosage of 90Gy and 30% isodose line tangential to the pons.
Topics: Adult; Aged; Aged, 80 and over; Cross-Sectional Studies; Female; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Pons; Radiosurgery; Radiotherapy Dosage; Retrospective Studies; Trigeminal Ganglion; Trigeminal Nerve; Trigeminal Neuralgia
PubMed: 30424930
DOI: 10.1016/j.neucir.2018.10.001 -
Cerebrovascular Diseases (Basel,... 2022Early neurological deterioration (END) occurs in patients with pontine infarction that is adversely associated with a long-term functional outcome. As basilar artery... (Review)
Review
BACKGROUND
Early neurological deterioration (END) occurs in patients with pontine infarction that is adversely associated with a long-term functional outcome. As basilar artery (BA) tortuosity may alter hemodynamics, we investigated whether factors including BA tortuosity are associated with END and poor outcome at 3 months.
METHODS
We reviewed patients with acute (<7 days from stroke onset) unilateral pontine infarction mainly involving the pontine base and/or tegmental regions from January 2017 through April 2021. END was defined as increase of ≥2 in total National Institutes of Health Stroke Scale (NIHSS) score or ≥1 in motor NIHSS score within first 72 h. A poor clinical outcome was defined as modified Rankin Scale (mRS) 3-6 at 3 months. The BA tortuosity index (TI) was measured: ([actual/straight length -1] x 100). To assess interobserver agreement, TI measurements were obtained by 2 independent raters.
RESULTS
The study included 245 patients; END occurred in 72 (29.3%) and 35 (14.2%) showed poor outcome at 3 months. Old age (odds ratio [OR] = 1.03, 95% confidence interval [CI] 1.004-1.062; p = 0.027), previous stroke history (OR = 2.36, 95% CI: 1.176-4.717; p = 0.016), lower initial NIHSS (OR = 0.72, 95% CI: 0.628-0.827; p < 0.001), and high BA TI (OR = 1.17, 95% CI: 1.062-1.295; p = 0.002) were associated with END. On the other hand, old age (OR = 1.04, 95% CI: 1.002-1.073; p = 0.037) and END (OR = 3.03, 95% CI: 1.429-6.403; p = 0.004) were associated with poor outcome at 3 months.
CONCLUSIONS
High BA tortuosity may be a factor associated with END in patients with pontine infarction. As END was related to unfavorable clinical outcome, this risk may have to be carefully considered in patients with high BA tortuosity.
Topics: Basilar Artery; Brain Stem Infarctions; Humans; Infant; Odds Ratio; Pons; Retrospective Studies; Stroke; Treatment Outcome
PubMed: 35240597
DOI: 10.1159/000522142 -
Neurosurgical Review Oct 2016Surgical approaches to the pons lump together different areas of the pons, such as the anterosuperior and the anteroinferior pons. These areas are topographically... (Comparative Study)
Comparative Study
Quantitative analysis of surgical exposure and surgical freedom to the anterosuperior pons: comparison of pterional transtentorial, orbitozygomatic, and anterior petrosal approaches.
Surgical approaches to the pons lump together different areas of the pons, such as the anterosuperior and the anteroinferior pons. These areas are topographically different, and different approaches may be best suited for one or the other area. We evaluated the exposure of the anterosuperior pons using different surgical approaches. We quantify the surgical exposure and surgical freedom to the anterosuperior pons afforded by the pterional transtentorial (PT), the orbitozygomatic with anterior clinoidectomy (OZ), and the anterior petrosal (AP) approaches. Five embalmed cadaver heads were used. The three approaches were executed on each side, for a total of 30 approaches. The area of maximal exposure of the anterosuperior pons was measured with the aid of neuronavigation. We also evaluated the feasible angles of approach in the vertical and horizontal planes. We were able to successfully expose the anterosuperior pons using all the selected approaches. In the PT and OZ approaches, mobilization of the sphenoparietal sinus can prevent over-retraction of the temporal bridging veins, while use of the endoscope can help in preserving the integrity of the fourth nerve while cutting the tentorium. The mean exposure area was largest for the AP and smallest for the PT; the surgical freedom was similar among all the approaches. However, there was no statistically significant difference among all the approaches in the exposure area or in the surgical freedom. There is no significant difference among the three evaluated approaches in exposure of the anterosuperior pons.
Topics: Cadaver; Cavernous Sinus; Craniotomy; Dura Mater; Humans; Neuronavigation; Neurosurgical Procedures; Pons
PubMed: 27075862
DOI: 10.1007/s10143-016-0710-2 -
BMJ Case Reports Apr 2022Millard-Gubler syndrome (MGS) is a ventral pontine syndrome due to an ipsilateral involvement of abducens and facial nerve with a contralateral hemiparesis or...
Millard-Gubler syndrome (MGS) is a ventral pontine syndrome due to an ipsilateral involvement of abducens and facial nerve with a contralateral hemiparesis or hemiplegia. Although classically described as a vascular brainstem syndrome, various other aetiologies such as infection or demyelination may lead to MGS. In this case, a young female presented with MGS, which was attributed to a strategically located infective granuloma of the brainstem. In countries, where tuberculosis is still considered an endemic, central nervous system involvement due to tuberculosis may have protean manifestations.
Topics: Brain Stem Infarctions; Facial Nerve; Facial Paralysis; Female; Hemiplegia; Humans; Pons
PubMed: 35414579
DOI: 10.1136/bcr-2021-248590 -
The Journal of Physiology May 2018Phasic activation of M1 muscarinic receptors generates transient inhibition followed by longer lasting excitation in neocortical pyramidal neurons. Corticopontine...
KEY POINTS
Phasic activation of M1 muscarinic receptors generates transient inhibition followed by longer lasting excitation in neocortical pyramidal neurons. Corticopontine neurons in the mouse prefrontal cortex exhibit weaker cholinergic inhibition, but more robust and longer lasting excitation, than neighbouring callosal projection neurons. Optogenetic release of endogenous ACh in response to single flashes of light (5 ms) preferentially enhances the excitability of corticopontine neurons for many tens of seconds. Cholinergic excitation of corticopontine neurons involves at least three ionic mechanisms: suppression of K 7 currents, activation of the calcium-dependent non-specific cation conductance underlying afterdepolarizations, and activation of what appears to be a calcium-sensitive but calcium-permeable non-specific cation conductance. Preferential cholinergic excitation of prefrontal corticopontine neurons may facilitate top-down attentional processes and behaviours.
ABSTRACT
Pyramidal neurons in layer 5 of the neocortex comprise two broad classes of projection neurons: corticofugal neurons, including corticopontine (CPn) neurons, and intratelencephalic neurons, including commissural/callosal (COM) neurons. These non-overlapping neuron subpopulations represent discrete cortical output channels contributing to perception, decision making and behaviour. CPn and COM neurons have distinct morphological and physiological characteristics, and divergent responses to modulatory transmitters such as serotonin and acetylcholine (ACh). To better understand how ACh regulates cortical output, in slices of mouse prefrontal cortex (PFC) we compared the responsivity of CPn and COM neurons to transient exposure to exogenous or endogenous ACh. In both neuron subtypes, exogenous ACh generated qualitatively similar biphasic responses in which brief hyperpolarization was followed by longer lasting enhancement of excitability. However, cholinergic inhibition was more pronounced in COM neurons, while excitatory responses were larger and longer lasting in CPn neurons. Similarly, optically triggered release of endogenous ACh from cholinergic terminals preferentially and persistently (for ∼40 s) enhanced the excitability of CPn neurons, but had little impact on COM neurons. Cholinergic excitation of CPn neurons involved at least three distinct ionic mechanisms: suppression of K 7 channels (the 'M-current'), activation of the calcium-dependent non-specific cation conductance underlying afterdepolarizations, and activation of what appears to be a calcium-sensitive but calcium-permeable non-specific cation conductance. Our findings demonstrate projection-specific selectivity in cholinergic signalling in the PFC, and suggest that transient release of ACh during behaviour will preferentially promote corticofugal output.
Topics: Acetylcholine; Action Potentials; Animals; Calcium; Cholinergic Agents; Female; Male; Mice; Mice, Inbred C57BL; Neurons; Optogenetics; Pons; Prefrontal Cortex; Visual Cortex
PubMed: 29330867
DOI: 10.1113/JP275194 -
Cerebellum (London, England) Apr 2024The term Pontocerebellar Hypoplasia (PCH) was initially used to designate a heterogeneous group of fetal-onset genetic neurodegenerative disorders. As a descriptive...
The term Pontocerebellar Hypoplasia (PCH) was initially used to designate a heterogeneous group of fetal-onset genetic neurodegenerative disorders. As a descriptive term, PCH refers to pons and cerebellum of reduced volume. In addition to the classic PCH types described in OMIM, many other disorders can result in a similar imaging appearance. This study aims to review imaging, clinical and genetic features and underlying etiologies of a cohort of children with PCH on imaging. We systematically reviewed brain images and clinical charts of 38 patients with radiologic evidence of PCH. Our cohort included 21 males and 17 females, with ages ranging between 8 days to 15 years. All individuals had pons and cerebellar vermis hypoplasia, and 63% had cerebellar hemisphere hypoplasia. Supratentorial anomalies were found in 71%. An underlying etiology was identified in 68% and included chromosomal (21%), monogenic (34%) and acquired (13%) causes. Only one patient had pathogenic variants in an OMIM listed PCH gene. Outcomes were poor regardless of etiology, though no one had regression. Approximately one third of patients deceased at a median age of 8 months. All individuals had global developmental delay, 50% were non-verbal, 64% were non-ambulatory and 45% required gastrostomy feeding. This cohort demonstrates that radiologic PCH has heterogenous etiologies and the "classic" OMIM-listed PCH genes underlie only a minority of cases. Broad genetic testing, including chromosomal microarray and exome or multigene panels, is recommended in individuals with PCH-like imaging appearance. Our results strongly suggest that the term PCH should be used to designate radiologic findings, and not to imply neurogenerative disorders.
Topics: Male; Child; Female; Humans; Infant; Cerebellar Diseases; Cerebellum; Pons; Magnetic Resonance Imaging; Developmental Disabilities; Nervous System Malformations
PubMed: 36971923
DOI: 10.1007/s12311-023-01544-2