面神经液压与面神经电图的相关性研究

目的　探讨面神经电图作为面神经减压手术指征的病理生理学基础。方法　利用电生理仪和伺服微变量微压系统 ,对正常和压榨伤后面瘫不同时期的豚鼠 ,作面神经电图检查 ,再采用微创测压法进行面神经液压的测量 ,得出面神经损伤后不同时期的面神经动作电位降幅及相应的面神经液压 ,并观察不同时期面神经光镜和电镜下的组织学改变。结果　面神经损伤 3d至 3周 ,随着面神经液压的升高 ,面神经动作电位降幅百分数亦增加 ,二者间有明显相关性 ,损伤后 2周和 3周 ,面神经液压和面神经动作电位降幅的相关系数分别为 0 88和 0 51。神经液压的变化与面神经Wallerian变性各期组织学改变相一致。结论　在面瘫 3周内 ,面神经电图的改变可间接反映面神经液压的变化 ,并可为面神经减压术的时机提供客观、可靠的实验依据。     

Research of relationship between endoneurial fluid pressure and electroneurography of the facial nerve]

OBJECTIVE: The relationship between endoneurial fluid pressure (EFP) and electroneurography (ENoG) of the facial nerve was studied in order to evaluate the ENoG as the basis of pathophysiology of the decompression of the facial nerve. METHODS: The values of ENoG were recorded by an instrument of physiology on the normal and crushed facial nerves of guinea pigs. Endoneurial fluid pressures were measured by a servo-nulling micropipette system at the same time. After the EFP were measured, the facial nerves were removed and fixed properly for examination under the light and electron microscope in order to determine the differences from various periods after injury. RESULTS: EFP in the facial nerve was changed significantly during the period of three days to three weeks later after crushed injury, and the percentage of degenerated facial nerve fibre was the same. There was positive correlation between ENoG and EFP. After crushed injury 2 and 3 weeks, the coefficient was 0.88 and 0.51, respectively. It could be found that extensive edema in endoneurial and perivascular spaces of the facial nerve occurred in early stage of injury, but numerous Schwann cells proliferation appeared in the later period. CONCLUSION: The change of ENoG could reflect the value of EFP relatively within three weeks after crushed injury. It was suggested that ENoG could be useful in evaluating the pathogenesis underlying facial palsy. And it could be provided a basis indication for decompression of the facial nerve.     

面神经损伤后面神经内压的变化

目的研究面神经损伤后神经内压和神经直径的变化，以探讨面神经减压术的必要性以及减压时机的选择。方法采用伺服微变量系统和测微尺对面神经挤压伤后不同时期的豚鼠分别进行神经内压及神经直径的测量。结果面神经高位挤压伤后，神经内压明显改变，压力高峰期在损伤后１周末，平均可达（１２．９４±１．６９）ｍｍＨｇ，为正常值的４～５倍，神经内压的升高持续２周，至第３和第４周恢复正常。面神经直径在伤后１周末最大，平均可达（１．０１±０．０８）ｍｍ。结论伺服测压系统测量实验动物的面神经内压将有助于面瘫病理生理的研究，为临床实施面神经减压术的时机选择提供实验参考。     

Changes in endoneurial fluid pressure in the crushed facial nerve]

OBJECTIVE: To investigate the changes in endoneurial fluid pressure (EFP) and diameter of the crushed facial nerves in guinea pigs in order to determine whether there is necessity and the opportunity of the facial nerves decompression in different stage after injury. METHODS: EFP were measured using a servo-nulling micropipette system in the normal and crushed facial nerves. RESULTS: The results showed that the EFP in the facial nerve increased significantly after compression. The highest pressure of EFP 12.94 +/- 1.69 mmHg occurred at the end of the first week after injury, which was 4 to 5 times as great as that of normal ones. This change lasted about two weeks, then it returned to normal at the third or the fourth week. The largest diameter of the facial nerve 1.01 +/- 0.08 mm was seen at the end of the first week after crush injury. CONCLUSION: It suggested that the servonulling micropiette system was useful in evaluating the pathogenesis of facial palsy. It could provide the laboratory basis for facial nerve decompression.     

Endoneurial fluid pressure in the facial nerve of guinea pigs and rabbits

Endoneurial fluid pressure (EFP) was measured in the facial nerve in rabbits and guinea pigs using a servo-controlled micropipette system. EFP in the tympanic segment was 5.3 +/- 1.2 cm H2O in rabbits and 4.1 +/- 0.9 and 4.2 +/- 0.9 cm H2O in the tympanic and mastoid segment respectively in guinea pigs, while EFP in the sciatic nerve was around 2 cm H2O. The higher pressure in the facial nerve may be related to the proximo-distal flow of the endoneurial fluid in peripheral nerves.     

A correlation study of endoneurial fluid pressure and electroneurography of the facial nerve

OBJECTIVE: The relationship between endoneurial fluid pressure (EFP) and electroneurography (ENoG) of the facial nerve was studied in order to evaluate the pathophysilogical basis of ENoG to serve as the criteria for decompression of the facial nerve. METHODS: While the values of ENoG were recorded by an instrument for physiology on the normal and crushed facial nerves of guinea pigs, EFPs were measured at the same time by a servo-nulling micropipette system. After the elevated EFP was measured, the facial nerves were removed and then fixed properly for examination under the light and electron microscope in order to determine the differences from various periods after injury. RESULTS: With the change of EFP in the facial nerve during the period from day 3 to the third week after crushed injury, the percentage of degenerated facial nerve fiber increased. There was a positive correlation between ENoG and EFP. The coefficient was 0.88 and 0.51 in the second and third week after crushed injury, respectively. Extensive edema in endoneurial and perivascular spaces of the facial nerve could be found at the early stage of injury, while proliferation of numerous Schwann cells appeared at the later stage. CONCLUSION: The change of ENoG could reflect the value of EFP relatively within 3 weeks after crushed injury. Our data indicate that ENoG could be useful to evaluate the pathogenesis underlying facial palsy.     

面神经内压微创测量的实验研究

目的：研究豚鼠面神经内压的正常值。方法：采用伺服微变量测压系统对２４只正常豚鼠进行面神经内压测量。结果：正常面神经内压：鼓室段和乳突段分别为２．８７±０．５１ｍｍＨｇ和２．７０±０．４３ｍｍＨｇ,鼓室段与乳突段的面神经内压约相等,神经内压在一定范围内呈规律性波动。结论：伺服测压系统将有助于研究面瘫患者的面神经病理生理活动。     

Effects of glycerol and mannitol on the interstitial fluid pressure of the facial nerve.

The pressure lowering effect of glycerol and mannitol on the interstitial fluid pressure of the facial nerve was studied in normal guinea pigs. The effect of low-molecular dextran on the interstitial fluid pressure of the facial nerve was also studied. Both peroral administration of glycerol and intravenous administration of mannitol lowered the interstitial fluid pressure of the facial nerve as well as the cerebrospinal fluid pressure. The pressure decrease in the facial nerve may be the result of a decreased cerebrospinal fluid pressure, caused by the administration of glycerol or mannitol. Low-molecular dextran did not cause significant pressure changes in the facial nerve.     

The relationship between spontaneous cerebrospinal fluid leak and idiopathic intracranial hypertension

Surgical treatment of spontaneous cerebrospinal fluid (CSF) leak is now performed by ENT surgeons, endonasal endoscopy being preferred to craniotomy as less invasive. However, it is often the symptom of underlying idiopathic intracranial hypertension, which lies outside the traditional sphere of ENT competence. Surgery is a necessary step, but should not obscure the need to treat the underlying pathology. This treatment is complex, and requires multidisciplinary team-work between otorhinolaryngologist, ophthalmologist, neurologist, neurosurgeon, radiologist, dietician, endocrinologist and psychotherapist. The present update details this multidisciplinary management to which the ENT surgeons must be attentive before and after spontaneous CSF leak repair.     

Positional relationship between the facial nerve and other structures of the temporal bone

The quantitative relationships between the position of the mastoid segment of the facial nerve, mastoid pneumatization and the positions of neighbouring structures are undetermined. Using high resolution computed tomography (HRCT), the positions of these structures were measured in 66 normal temporal bones. A new method for measuring the volume of pneumatization in the temporal bone based on the serial digital images of CT was designed. The method of partial correlation analysis was used to find the real relationship of the two variables. The results suggest that the factors that influence the position of the mastoid segment of the facial nerve are complicated and multiple. The development of the cranium including the temporal bone, the temporal bone pneumatization and the variable position of the jugular bulb are considered to be important factors.     

Congenital cerebrospinal fluid pressure labyrinth]

The audiograms and CT scans of three children with a bilateral congenital mixed deafness are presented. Two children underwent an exploratory tympanotomy revealing a fixed stapes footplate: a perilymph gusher arose during platinotomy in both cases. The gusher was controlled successfully with a large fat graft in both children, and hearing remained unchanged. Two of the children were brothers: they had no other deformities except an enlarged fundus of the auditory canal on CT scans, and no clearly defined bony barrier to the vestibule, suggesting a cerebrospinal fluid fistula. Neither a patent nor an abnormal cochlear aqueduct could be detected in all three cases. It is likely that the three patients present an X-linked mixed deafness syndrome with fixation of the stapedial foot plate and perilymph gusher. A classification of congenital perilymph-CSF shunts is proposed.     

Opening cerebrospinal fluid pressure guides the management of cerebrospinal fluid leakage after acoustic neuroma surgery.

OBJECTIVE: To assess the value of cerebrospinal fluid pressure as a decisional factor for immediate surgical revision in cerebrospinal fluid leakage after acoustic neuroma removal. STUDY DESIGN: Prospective study. SETTING: Tertiary referral center. PATIENTS: Between 1998 and 2001, 220 patients were operated on for acoustic neuroma by different transpetrosal approaches. Among 24 patients (12%) presenting postoperative cerebrospinal fluid leakage, those with meningitis or with hydrocephalus were excluded. Fifteen patients were included in this study. METHODS: Each patient had initial conservative treatment with serial depletive lumbar punctures and cerebrospinal fluid pressure measurements associated with oral acetazolamide. Surgical revision was decided on in case of persistent cerebrospinal fluid leakage. RESULTS: In eight patients with high cerebrospinal fluid pressure (18+/-1.4 cm H2O; range, 14-28 cm H2O), cerebrospinal fluid leak disappeared in 3 days after conservative treatment. Seven other patients required surgical revision for persistent cerebrospinal fluid leakage. Revision surgery was efficient in six patients with low cerebrospinal fluid pressure (8+/-1.3 cm H2O, range, 3-12 cm H2O). In the remaining patient with high cerebrospinal fluid pressure (18 cm H2O), cerebrospinal fluid leakage continued despite surgical revision, requiring lumboperitoneal shunting. CONCLUSION: The cerebrospinal fluid pressure value may be used as a decisional indicator for cerebrospinal fluid leakage treatment after acoustic neuroma surgery. Low cerebrospinal fluid pressure leakage would imply a revision surgery procedure without delay, whereas high cerebrospinal fluid pressure leakage would imply conservative treatment.     

Hearing loss and cerebrospinal fluid pressure: case report and review of the literature

A decrease in cerebrospinal fluid pressure may result in an endolymphatic hydrops through a patent cochlear aqueduct or through the fundus of the internal auditory canal. This hydrops typically leads to low-frequency sensorineural hearing loss. We describe the case of a man who presented with a subjective and objective hearing loss in addition to a headache 4 days after he had undergone a dural puncture. We treated him with a standard epidural blood patch. Immediately after treatment, his hearing improved and his headache resolved.     

The anatomic relationship between the second genu of the facial nerve and the incus: a high-resolution computed tomography study

OBJECTIVE: This study defines the three-dimensional location of the posterior-most point of the tympanic segment of the facial nerve (TSFN) relative to the posterior-most point of the short process of the incus, using ultrahigh-resolution computed tomography (CT) of the temporal bone. STUDY DESIGN, SETTING, AND PATIENTS: Included were patients who had been referred for CT of the temporal bone for various reasons other than suspected pathologic conditions of the middle ear. The decision whether to include a patient in the study was based on the referring physician's referral note for the examination. INTERVENTION: All of the patients underwent axial CT of the temporal bone, with consecutive slices of 1.1 mm width and 0.5-mm increments. MAIN OUTCOME MEASURES: The posterior-most point of the short process of the incus was identified on axial CT and was superimposed onto a lower axial slice in which the posterior-most point of the TSFN was identified. Its shortest distance to the TSFN was measured. Afterward, the length of the TSFN that remained posterior to the perpendicular of the posterior-most point of the short process of the incus was measured by measuring the length of TSFN that could be seen posterior to the point of bisection of the line marking the shortest distance between the posterior-most point of the short process of the incus and the FN in the previous measurement. The measurements were performed on 30 normal temporal bones. RESULTS: The shortest distance measured between the posterior-most point of the short process of the incus and the TSFN was, on average, 3.31 mm for all 30 ears (range 2-4.8 mm). The length of TSFN that could be seen posterior to the perpendicular of the most posterior point of the short process of the incus was, on average, 2.70 mm (range 1.80-3.90 mm). CONCLUSIONS: In addition to defining the spatial location of the posterior-most point of the TSFN, this study also offers a practical method by which the surgeon can evaluate, preoperatively, how far medial to the incus and how much posterior to the posterior-most point of the short process of the incus the facial nerve is located.     

Search for Herpesviruses in cerebrospinal fluid of facial palsy patients by PCR

CONCLUSIONS: Herpes simplex virus 1 (HSV-1) and varicella-zoster virus (VZV) DNA were not detected in the cerebrospinal fluid (CSF) of patients with acute idiopathic peripheral facial palsy (Bell's palsy). Our results indicate either the absence of these viruses or the presence of technical shortcomings. The role of human herpesvirus 6 (HHV-6) in this disorder and the significance of a positive HHV-6 DNA finding in the central nervous system need further investigation. OBJECTIVE: Our goal was to determine whether DNA of HSV-1, VZV, or HHV-6 can be found by polymerase chain reaction (PCR) in the CSF of peripheral facial palsy patients. MATERIALS AND METHODS: We used PCR to detect the presence of HSV-1, VZV, and HHV-6 DNA in CSF. This was a retrospective case control study with 33 peripheral facial palsy patients (34 CSF samples) in the study group (26 with Bell's palsy, 5 with simultaneously diagnosed herpesvirus infection, 1 with puerperal facial palsy, 1 with Melkersson-Rosenthal syndrome). The control group included 36 patients, most with diagnosed or suspected Borreliosis and facial palsy or sudden deafness. RESULTS: One patient with Bell's palsy had HHV-6 DNA in CSF. Neither HSV-1 nor VZV DNA was detected in patients or controls.     

Basic principles of cerebrospinal fluid metabolism and intracranial pressure homeostasis

Significant progress has been made in understanding the production,circulation, and absorption of CSF. In part because of autoregulation, rapid changes in arterial pressure produce parallel but significantly dampened changes in CSF pressure. Chronic arterial hypertension rarely affects ICP,but changes in venous pressure are transmitted directly into the CSF, taking precedence over arterial effects. An understanding of basic CSF physiology,particularly in relation to ICP homeostasis, is important for surgeons treating intracranial hypertension, low ICP pressure, and spontaneous,traumatic, or iatrogenic CSF leakages. The principles discussed in this article are valuable to remember when planning surgical procedures in the head and neck, both to prevent and to treat potential complications related to increased or decreased CSF pressure.