Intraoperative brainstem auditory evoked potential observations after trigeminocardiac reflex during cerebellopontine angle surgery

Sinus arrest with prolonged asystole due to the trigeminocardiac reflex during application of local anaesthetic in the nasal mucosa

The trigeminocardiac reflex (TCR) is defined as a sudden onset of parasympathetic dysrhythmias during stimulation of the trigeminal nerve. We describe a peripheral variation of TCR during manipulation of the nasal mucosa. A 42-year-old patient suffering from severe obstructive sleep apnoea was scheduled for surgical treatment. After inducted anaesthesia, the surgeon infiltrated the nasal mucosa with a local anaesthetic. The patient immediately showed an asystole and was treated with ephedrine and five chest compressions, despite spontaneous sinus rhythm return after ceasing of manipulation. Treatment with atropine established this TCR episode and ensured an event-free surgery.The authors present here, for the first time, a prolonged asystole caused by the TCR, triggered by minimal manipulation of the nasal mucosa. This severe manifestation of peripheral TCR demonstrates its importance in daily clinical business. This case was treated according to a modified treatment algorithm for all subtypes of TCR which is presented here.

The clinical surrogate definition of the trigeminocardiac reflex: Development of an optimized model according to a PRISMA-compliant systematic review

BACKGROUND

The trigeminocardiac reflex (TCR) is defined as sudden onset of parasympathetic dysrhythmias including hemodynamic irregularities, apnea, and gastric hypermotility during stimulation of sensory branches of the trigeminal nerve. Since the first description of the TCR 1999, there is an ongoing discussion about a more flexible than the existing clinical definition. Aim of this work was to create a clinical surrogate definition through a systematic review of the literature.

METHODS

In this meta-analysis study, literature about TCR occurrences was, according to the Preferred Reporting Items for Systematic Reviews and Meta-Analysis statement, systematically identified through various search engines including PubMed (Medline), Embase (Ovid SP), and ISI Web of Sciences databases from January 2005 to August 2015. TCR was defined as a drop of heart rate (HR) below 60 bpm or 20% to the baseline. We extracted detailed data about hemodynamic changes and searched for connections between arterial blood pressure (BP) and HR changes during such episodes.

RESULTS

Overall 45 studies harboring 57 patients were included in the study but only 32 patients showed sufficient data for final analyze. HR showed a nonlinear behavior with a "tipping point" phenomena that differs in variance from the central/peripheral (20-30% drop) to ganglion (40-49% drop). BP showed a linear behavior with a "central limit" phenomena not differing in variance in the whole subgroup (30-39% drop). An analyzation of the correlation between BP and HR showed a trend to a linear correlation.

CONCLUSIONS

We can show for the first time that HR is the dominant variable in the TCR and present a new surrogate definition model. This model and the role of BP must be better investigated in further studies.

Effects of hyperbaric oxygen and nerve growth factor on the long-term neural behavior of neonatal rats with hypoxic ischemic brain damage

Purpose:

To evaluate the effects of HBO (Hyperbaric oxygen) and NGF (Nerve growth factor) on the long-term neural behavior of neonatal rats with HIBD (Neonatal hypoxic ischemic brain damage).

Methods:

The HIBD model was produced by ligating the right common carotid artery of 7 days old SD (Sprague-Dawley) rats followed by 8% O2 + 92% N2 for 2h. Totally 40 rats were randomly divided into 5 groups including sham-operated group, HIBD control group, HBO treated group, NGF treated group and NGF + HBO treated group. The learning and memory ability of these rats was evaluated by Morris water maze at 30 days after birth, and sensory motor function was assessed by experiments of foot error and limb placement at 42 days after birth.

Results:

The escape latency of HBO treated group, NGF treated group and NGF + HBO treated group was shorter than that of HIBD control group (p<0.01) and longer than that of sham-operated group. The piercing indexes of 3 treated groups were higher than that of HIBD control group (p<0.01).

Conclusion:

Hyperbaric oxygen and nerve growth factor treatments may improve learning and memory ability and sensory motor function in neonatal rats after hypoxic ischemic brain damage.

Nerve protective effect of Baicalin on newborn HIBD rats

OBJECTIVES

To investigate the nerve protective effect and mechanism of baicalin on newborn rats with hypoxic ischemic brain damage (HIBD).

METHODS

A total of 64 SD newborn rats were randomly divided into control group, model group, nerve growth factor group and baicalin group, with 16 in each group. Left carotid artery ligation method was adopted to establish the HIBD model except for in control group, which was treated with intraperitoneal injection of salin e10 mL/kg for 3 d. After oxygen recovery on hypoxia ischemia rats, intraperitoneal injection of saline 10 mL/kg was adopted in model group for 3 d. Intraperitoneal injection of nerve growth factor injection 50 μg/kg per day was adopted in nerve growth factor group for 3 d; intraperitoneal injection of radix scutellariae 16 mg/kg per day was adopted in baicalin group for 3 d after modeling. Four rats of each group were sacrificed at Day 1, 2, 3, 7 for microscopic observation of pathological morphological changes in brain tissue after HE staining, S-P immunohistochemical method was used for observation of Fas and FasL expression in brain cells.

RESULTS

Neat structure of cells was observed in control group; edema cells in disordered arrangement was observed in model group, with some cells necrosis and cavity change; tissue injury in nerve growth factor group and baicalin group was significantly lighter than that in model group; Fas and FasL expression in model group, nerve growth factor group and baicalin group were significantly higher than that in control group at different time points (P<0.05); Fas and FasL expression in nerve growth factor group and baicalin group were significantly lower than that in model group at different time points (P<0.05); There was no statistical difference of Fas, FasL expression at each time point between nerve growth factor group and baicalin group (P>0.05).

CONCLUSIONS

Baicalin can reduce expression of Fas and FasL in HIBD rats, inhibit apoptosis of nerve cells, thus achieve the protective effect on HIBD rat nerves.

Effect of G-CSF and TPO on HIBD in neonatal rats

OBJECTIVE

To observe effect of granulocyte colony-stimulating factor (G-CSF) and restructure human thrombopoietin on hypoxic-ischemic brain damage (HIBD) in new born rats.

METHODS

A total of 60 neonatal SD rats were selected and divided into 4 groups, with 15 in each group. Group A served as control group. Rats of Groups B-D were prepared for HIBD model by ligation of left common carotid artery combined with hypoxia method. Rats of Group A were only completed with free left common carotid artery without ligation and hypoxia operation. After HIBD model preparation, Group B was administrated with subcutaneous injection of normal saline for placebo treatment; Group C was administrated with cervical subcutaneous injection of 0.5 μg/10 g granulocyte colony stimulating factor (G-CSF) for 5 d (Once a day); Group D was administrated with intraperitoneal injection of 15 U/10 g recombinant human thromobopoietin (rhTPO) for treatment. After modeling for 7, 14 and 21 d, 5 rats were sacrificed in each group, respectively. Brain quality damage (%) conditions of experimental animals in each group were compared in different time points, and cerebral histopathological changes of each group were observed. Expression of nestin in rats of each group was detected by immunohistochemical method.

RESULTS

After modeling for 7, 14 and 21 d, brain quality damages (%) of Groups B, C and D were significant higher than that of in Group A (P<0.05), while brain quality damage (%) degree of Group B was the highest in different time points, followed by Groups D and C, respectively. It was significant different compared among groups (P<0.05). The histopathological observation showed that degrees of brain damages in Groups C and D were significant lower than that of in Group B. After modeling for 7, 14 and 21 d, nestin positive cell populations in Groups B, C, and D were significant higher than Group A (P<0.05). Nestin cell populations of Group C in different time points were significant higher than Groups B and D (P<0.05). There was no significant difference in nestin positive cell populations in the above time points between Groups B and D (P>0.05).

CONCLUSIONS

Both G-CSF and TPO can protect the nervous system of HIBD neonatal rats. G-CSF can promote the proliferation and differentiation of neural precursor cells to decrease the degeneration and necrosis of nerve cell. TPO can obviously ameliorate morphology index of HIBD rats. Through regulating ratio of TIMP-1 and MMP-9, TPO can maintain the integrity of blood brain barrier to relieve the occurrence of brain damage.

Altered brainstem auditory evoked potentials in a rat central sensitization model are similar to those in migraine

Migraine symptoms often include auditory discomfort. Nitroglycerin (NTG)-triggered central sensitization (CS) provides a rodent model of migraine, but auditory brainstem pathways have not yet been studied in this example. Our objective was to examine brainstem auditory evoked potentials (BAEPs) in rat CS as a measure of possible auditory abnormalities. We used four subdermal electrodes to record horizontal (h) and vertical (v) dipole channel BAEPs before and after injection of NTG or saline. We measured the peak latencies (PLs), interpeak latencies (IPLs), and amplitudes for detectable waveforms evoked by 8, 16, or 32 kHz auditory stimulation. At 8 kHz stimulation, vertical channel positive PLs of waves 4, 5, and 6 (vP4, vP5, and vP6), and related IPLs from earlier negative or positive peaks (vN1-vP4, vN1-vP5, vN1-vP6; vP3-vP4, vP3-vP6) increased significantly 2h after NTG injection compared to the saline group. However, BAEP peak amplitudes at all frequencies, PLs and IPLs from the horizontal channel at all frequencies, and the vertical channel stimulated at 16 and 32 kHz showed no significant/consistent change. For the first time in the rat CS model, we show that BAEP PLs and IPLs ranging from putative bilateral medial superior olivary nuclei (P4) to the more rostral structures such as the medial geniculate body (P6) were prolonged 2h after NTG administration. These BAEP alterations could reflect changes in neurotransmitters and/or hypoperfusion in the midbrain. The similarity of our results with previous human studies further validates the rodent CS model for future migraine research.

Usefulness of case reports to improve medical knowledge regarding trigemino-cardiac reflex in skull base surgery

We describe the discovery of the trigemino-cardiac reflex by Schaller in 1999 and the continued improvement of the knowledge about the trigemino-cardiac reflex involved in neurosurgery, especially in skull base surgery, during the past several years. The achieved medical progress could be gained only by the practical experience described by different case reports and later case series that have been published in several principal scientific journals. Additionally, we explain the scientific as well as clinical importance of the communication of the case reports on TCR. Special reference has been given to the validity of the case reports for new phenomena in clinical medicine.