Clinical Neuroscience

An endoscope-assisted craniometric cadaveric study for the brain stem and the cisternal segment of the trochlear nerve

BAŞAK Tulgar Ahmet 1, ÇAKICI Nazlı 2

JULY 30, 2022

Clinical Neuroscience - 2022;75(07-08)


Journal Article

This study analyzed the relationship of trochlear nerve with neurovascular structures using craniometric measurements. The study was aimed to understand the course of trochlear nerve and minimize the risk of injury during surgical procedures. Twenty trochlear nerves of 10 fresh cadavers were studied bilaterally using endoscopic assistance through the view afforded by the lateral infratentorial-supracerebellar, and the combined presigmoid-subtemporal transtentorial approaches. Trochlear nerves were exposed bilaterally taking seven parameters into consideration: the distance between the cisternal segment of trochlear nerve and vascular structures (superior cerebellar artery/SCA; posterior cerebral artery/PCA), the origin of the trochlear nerve in the brain stem, the angle in the level of tentorial junction, length, diameter, and length of nerve in the cisternal segment. We identified the brain stem and cisternal segments of the trochlear nerve. The lateral infratentorial supracerebellar approach allowed the exposure of the cisternal segments (crural and ambient cisterns), including the origin of the nerve in the brain stem. The combined presigmoid-subtemporal transtentorial approaches provided visualization of the cisternal segment of the nerve and the free edge of the tentorium. In this study, the mean length and width of the trochlear nerve in the cisternal segment were 30.3 and 0.74 mm, respectively. Length of the trochlear nerve from its origin to its dural entrance was 37.2 mm, tentorial dural entrance angle of the trochlear nerve and exit angle of the trochlear nerve from the brain stem were 127.0 degrees and 54 degrees, PCA to trochlear nerve in mid ambient cistern and SCA to trochlear nerve in mid ambient cistern were 7.3 mm and 6.8mm. Trochlear nerve is vulnerable to injury during the surgical procedures. Therefore, it is necessary to have a sufficient knowledge of the anatomy of cisternal segment and its relationship with adjacent neurovascular structures. The anatomical and craniometric data can be helpful in middle and posterior fossa surgery in minimizing the potential injury of the trochlear nerve.


  1. Neurosurgery Department, VKV American Hospital, Nişantaşı, İstanbul, Turkey
  2. Neurosurgery Department, Medicana Internatıonal Hospital, Beylikdüzü, İstanbul, Turkey



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MAGYAR Máté , KÖKÖNYEI Gyöngyi , BAKSA Dániel, GALAMBOS Attila, ÉDES Edit Andrea , SZABÓ Edina , KOCSEL Natália , GECSE Kinga , DOBOS Dóra , GYÜRE Tamás , JUHÁSZ Gabriella , ERTSEY Csaba

Previous studies using generic and disease specific instruments showed that both migraine and medication overuse headache are associated with lower health-related quality of life (HRQoL). The aim of our study was to assess HRQoL differences in migraineurs and in patients with MOH and to examine how headache characteristics such as years with headache, aura symptoms, triptan use, headache pain severity and headache frequency are related to HRQoL. In this cross-sectional study 334 participants were examined (248 were recruited from a tertiary headache centre and 86 via advertisements). The Comp­rehensive Headache-related Quality of life Questionnaire (CHQQ) was used to measure the participants’ HRQoL. Data showed normal distribution, therefore beside Chi-squared test parametric tests (e.g. independent samples t-test) were used with a two-tailed p<0.05 threshold. Linear regression models were used to determine the independent effects of sex, age, recruitment method, headache type (migraine vs. MOH) and headache characteristics (presence of aura symptoms, years with headache, headache pain severity, headache frequency and triptan use) separately for each domain and for the total score of CHQQ. Significance threshold was adopted to p0.0125 (0.05/4) to correct for multiple testing and avoid Type I error. Independent samples t-tests showed that patients with MOH had significantly lower scores on all CHQQ domains than migraineurs, except on the social subscale. Results of a series of regression analyses showed that triptan use was inversely related to all the domains of HRQoL after correction for multiple testing (p<0.0125). In addition, headache pain severity was associated with lower physical (p=0.001) and total scores (p=0.002) on CHQQ subscales. Based on the results, different headache characteristics (but not the headache type, namely migraine or MOH) were associated with lower levels of HRQoL in patients with headache. Determining which factors play significant role in the deterioration of HRQoL is important to adequately manage different patient populations and to guide public health policies regarding health service utilization and health-care costs.

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Acute oropharyngeal palsy is a rare variant of Guillain-Barré syndrome. In our study we present the case of a 63-year-old man with general symptoms who was diagnosed with diabetic ketoacidosis and prescribed insulin therapy. Two weeks later, the patient complained of paraesthesia of the perioral region and the tip of the tongue, dysphagia, and dysarthria. These symptoms were initially thought to be complications of the patient’s type-1 diabetes. Due to rapidly developing paraparesis, the patient became bedridden. Clinical symptoms, cerebrospinal fluid analysis and a nerve conduction study resulted in a diagnosis of acute oropharyngeal palsy, a variant of Guillain-Barré syndrome. After five consecutive days of intravenous immunoglobulin treatment, neurological symptoms improved and the need for insulin ceased. One year later, the patient’s only remaining neurological symptom was loss of tendon reflexes in the lower extremities. Furthermore, the patient’s blood glucose level was normal without the use of medications or a special diet. Here, we report that oropharyngeal palsy can co-occur with diabetic ketoacidosis, and that immuntherapy is effective in treating both oropharyngeal palsy and type-1 diabetes. To our knowledge, this is the first description of a patient presenting with acut oropharyngeal palsy concomitant with diabetic ketoacidosis.

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Multiple sclerosis is an autoimmune disease of the central nervous system, with myelin degeneration and Relapsing-Remitting Multiple Sclerosis (RRMS) as the most common type. The aim of this study was to determine the levels of Neurofilament Light Chain (NFL) and Orexin-A (OXA) in patients with RRMS and compare it with healthy control subjects’ data. In this case-control study of 61 subjects, serum and cerebrospinal fluid samples were collected from 23 RRMS patients and 38 healthy control subjects. NFL and OXA levels were determined in cerebrospinal fluid and serum samples using enzyme-linked immunosorbent assay kits. Self-reported questionnaires were also administered to evaluate fatigue severity and impact. Receiver operating characteristic curve analysis was used to determine the optimal cut-off value of NFL and OXA. The NFL and OXA concentrations in cerebro­spinal fluid of RRMS patients were significantly higher than those of the control group (p < 0.001), but no sig­nificant difference was found in the serum concentrations (p = 0.842, p = 0.597, respectively). The cut-off values were found to be 1.194 ng/ml for NFL and 77.81 pg/ml for OXA in cerebrospinal fluid. A positive correlation was found between the Expanded Disability Status Scale and Epworth Sleepiness Scale in RRMS patients (ρ = 0.49, p = 0.045). These results suggest that increased levels of both NFL and OXA in cerebrospinal fluid reflect neuronal destruction in RRMS. Further research of neurodegeneration should focus on neuropeptides to determine the possible roles in RRMS pathogenesis.

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Postoperative cognitive dysfunction (POCD) is a multifactorial image characterized by insufficiency in features such as the ability to perform tasks requiring high brain functions. Cognitive dysfunction such as memory loss and decreased concentration, confusion, and delirium are common conditions in some patients in the early period after major surgical interventions such as cardiac surgery. POCD causes delays in postoperative recovery, long return-to-work times, and decreased quality of life. This study aims to demonstrate POCD in early and late stages in patients undergoing cardiac surgery through the Montreal Cognitive Assessment (MoCA) and the Mini Mental Test (MMT). In addition, we aim to determine predictive factors with these neurocognitive tests. MMT and MoCA tests were applied to the patients included in the study before cardiac surgery, on the sixth postoperative day and third month. Neuro­cognitive dysfunction detected on the sixth postoperative day was accepted as an early period, its detection in the postoperative third month was accepted as a late period. 127 patients without neurocognitive dysfunction in the preoperative period were included in the study. For early neurocognitive impairment, age, mean platelet volume (MPV), New York Heart Association (NYHA) classification, x-clamp time, cardio-pulmonary bypass (CPB) time, postoperative intensive care and hospital stay duration, and an event of acute myocardial infarction (AMI) in the preoperative period were determined as predictive factors. In addition, in late-period of neurocognitive dysfunction age, MPV, NYHA classification, x-clamp duration, CPB time, postoperative intensive care and hospital stay duration were shown as predictors of neurocognitive dysfunction. The results of our study support the literature findings showing that delirium is associated with a decline in cognitive functions three months after cardiac surgery. As a result, the lack of agreed diagnostic tests in the definition of POCD makes it difficult to standardize and interpret the research in this area. Therefore, a consensus to be reached in the diagnosis of POCD will ensure the use and correct interpretation of neurophysiological tests. In our study, advanced age and long hospital and intensive care stays were shown as predictive factors for both early and late neurocognitive dysfunctions. Furthermore, smoking was shown as a predictive factor only for late neurocognitive dysfunction.

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