The evaluation of brain CBF and mitochondrial function by a fiber optic tissue spectroscope in neurosurgical patients.

The brain of neurosurgical patients are exposed to various manipulations in the ICU or during surgery. Under such conditions brain O2 balance may become negative and as a result brain vitality and function will deteriorate. In order to evaluate brain vitality in real time it is important to measure more than one parameter. The multiparametric monitoring system used in our previous study to monitor comatose patients (Mayevsky et al., Brain Res. 740: 268-274, 1996) was changed into a "simplified" tissue spectroscope for real time monitoring of brain O2 balance. Mitochondrial function was evaluated by monitoring the NADH redox state by surface fluorometry. Microcirculatory blood flow was assessed by laser Doppler flowmetry. The combined optical probe was located on the surface of the brain during various neurosurgical procedures and the responses were recorded and presented in real time to the surgeon. A total of 32 patients were monitored during various procedures. The results could be summarized as follows: 1. Hypercapnia led to 3 different types of responses. In two patients the 'stealing' like event was recorded. In the other 7 patients the responses to high CO2 was not detectable. In the last group of 6 patients a clear CBF elevation was recorded with variable response of mitochondrial NADH. 2. Our monitoring device was able to evaluate the efficacy of the STA-MCA anastomosis during aneurysm surgery. 3. A significant correlation was recorded between CBF and NADH redox state during changes in blood pressure, papaverine injection, spontaneous drop in blood supply to the brain or during releasing of high ICP levels. We conclude that in order to evaluate the metabolic state of the brain during neurosurgical procedures it is necessary to monitor both CBF and mitochondrial NADH by using the tissue spectroscope.

Microsurgical anatomy of the facial nerve trunk.

Dissection and manipulation of the facial nerve (FN) trunk between its exit from the cranial base through the stylomastoid foramen (SMF) and its bifurcation is a critical step in various otologic, plastic and neurosurgical procedures. This study demonstrates the anatomical relationships and variability of the FN trunk with emphasis on some important morphometric data, particularly with relevance to hypoglossal-facial nerve anastomosis (HFA). Bilateral microsurgical dissection was performed on twenty-three human cadavers fixed with formalin. The whole trunk of the FN was exposed, its diameter at the SMF and its length were measured, its branches were observed and the site of its bifurcation was determined. Anastomotic connections with other nerves and blood supply of the trunk were studied. The FN invariably emerged from the cranial base through the SMF. Its diameter upon its emergence from the foramen was 2.66 +/- 0.55 mm. Two branches consistently originated from the trunk: the posterior auricular nerve and the nerve to the digastric muscle. Less consistent were the communicating branch with the glossopharyngeal nerve and the nerve to the stylohyoid muscle. The bifurcation of the FN occurred before its penetration into the parotid gland in 15% of cases and within the gland in 85%. The length of the FN trunk was 16.44 +/- 3.2 mm. Anastomoses between the FN and other nerves were observed in one-third of the dissections. The blood supply to the FN trunk was provided by the stylomastoid artery that was identified in 91% of cases. Understanding the microsurgical anatomy of the FN trunk is essential for performing any surgical procedure in the relevant region. Surgical implications of this study are presented with emphasis on HFA surgery.

Paraganglioma of the pituitary fossa: diagnosis and management.

Paraganglioma of the sellar area is extremely rare with only six cases having been reported in the literature. Surgical removal of these tumors is difficult, and the transsphenoidal approach usually results in limited resection. Most authors who published reports on this tumor recommended radiation therapy after partial removal of the tumor. However, considering the benign nature of these tumors, the risk of radiation-induced endocrine insufficiency and optic neuropathy and the lack of proven effectiveness of radiotherapy, its value remains controversial. We describe a 48-year-old woman with parasellar paraganglioma who presented with headaches, visual loss and oligomenorrhea. Magnetic resonance imaging (MRI) showed an invasive tumor in the sellar and parasellar areas which extended to both cavernous sinuses and compressed the optic chiasm and the left internal carotid artery. Surgery by the transsphenoidal approach enabled only limited biopsy of the tumor. The patient was reoperated by an extended pterional approach which resulted in a subtotal removal of the tumor and adequate decompression of the adjacent structures. She received no adjuvant treatment during the 8-year postsurgical follow-up and remained in good health. A repeated MRI showed no change in the size of the residual tumor. Contrary to the therapeutic recommendations described in previous reports, we favor postoperative adjuvant therapy only if the symptoms or signs of cranial nerve compression persist following maximal tumor removal, or if there is evidence of subsequent growth of residual tumor.

Diagnosis and management of posttraumatic oculorrhea.

Posttraumatic cranio-orbital cerebrospinal fluid (CSF) fistula is very rare. Diagnosis of these fistulas may be difficult, and it is possible that this complication of craniofacial injury is underdiagnosed. Early recognition and adequate treatment is of paramount importance to prevent hazardous complications. The authors report the case of a 20-year-old woman in whom a CSF leak developed through the medial canthus area of her eye after she sustained a mild sports-related injury. Clinical examination and chemical analysis of the fluid led to the correct diagnosis, and the leak was stopped with conservative treatment. It is proposed that a CSF leak through the eye be termed "oculorrhea" as compared with otorrhea and rhinorrhea. The mechanism of the fistula in this patient is discussed, as is the pertinent radiologically demonstrated anatomy and the mechanism of injury. Management and controversies are also discussed.

TRH is a tonic secretagogue in growth hormone secreting but not in nonfunctioning pituitary tumors.

In most patients with growth hormone (GH) secreting pituitary adenomas and clinically nonfunctioning pituitary tumors (NFPT) the intravenous injection of thyrotropin releasing hormone (TRH) augments the secretion of GH and subunits of gonadotropin hormones respectively. Similar hormone responses to TRH have been detected in rat pituitary cell lines and in primary human pituitary tumor cultures in vitro. Nevertheless the TRH effect on tumor hormonal secretion has not been well characterized. In the present study we examined TRH-induced hormone secretion in GH secreting tumors and in NFPT in vitro. Cultured cells secreted betaLH and betaFSH (NFPT) or GH (GH secreting adenomas) up to 14 days in culture. In NFPT TRH (10(-8) mol/l) elicited peak betaLH and betaFSH secretion at 60 to 90 min, with no further increase at 24 h. TRH-stimulated GH secretion peaked at 90-120 min, and decreased after 3 h, but a secondary rise occurred after 24 h of incubation. Chronic daily exposure to TRH followed by an acute TRH challenge resulted in a further increase of GH secretion after one hour. In contrast, acute TRH administration following chronic exposure did not elicit increased P-subunits secretion in NFPT. Coadministration of cycloheximide did not change TRH induced beta-subunits secretion in NFPT. However, when it was administered 24 h prior to TRH, it blocked both basal and TRH induced beta-subunits levels in NFPT. Cycloheximide had no effect on basal or stimulated GH secretion when administered concomitantly or 24 h before TRH. Incubation of cultured GH secreting tumors with cycloheximide during 5 days blocked both basal and TRH stimulated GH secretion, thus indicating dependency on protein synthesis during the chronic, secondary phase. Since the acute secretion was not affected by coadministration of cycloheximide, these early increases in hormone levels apparently reflect the release of stored hormone. In summary, GH secreting adenomas and NFPT differ significantly in their hormonal response to continuous exposure to TRH. The mechanisms underlying the sustained effect of TRH on GH secretion in vitro remain to be investigated. If endogenous TRH exerts a similar continuous effect it may contribute to the disregulated GH secretion in acromegaly.

Brain viability and function analyzer: multiparametric real-time monitoring in neurosurgical patients.

We have developed the Brain Viability (BVA) and Brain Function (BFA) Analyzers for monitoring the following parameters from the human cerebral cortex cerebral blood flow: (CBF), NADH redox state, Electro corticography (ECoG), brain temperature, extracellular K+, DC potential and intracranial pressure (ICP). The BVA monitors the first 4 parameters only. The Brain viability probe (BVP) and Brain function multiprobe (BFM) were used during 11 operations and in 18 ICU patients, respectively. Preliminary results from the OR showed that 5 patients exhibited a typical increase in CBF in response to changes in end-tidal CO2 without a significant change in the NADH redox state. In 4 other patients no changes in CBF and NADH were observed. Two patients exhibited a "steeling response", i.e., a decrease in CBF and an increase in NADH. In 18 comatose patients monitored in the ICU, the ICP, CBF and ECoG were measured correctly in most patients, whereas NADH and K+ were more problematic. One patient exhibited a typical response, may be due to repeated cortical spreading depression cycles and an ischemic depolarization event. Continuous realtime multiparametric monitoring in neurosurgical patients is feasible and practical in the OR and the ICU. The information provided could be used as a diagnostic tool to guide the procedures or treatment given to the patients.

Real-time multiparametric monitoring of the injured human cerebral cortex--a new approach.

Intracranial pressure (ICP) is currently the main parameter monitored following severe head injury or during the post operative period in neurosurgical patients. The normal cerebral cortex depends upon a continuous supply of O2, and direct coupling exists between adequate cerebral blood flow (O2 supply) and ion homeostasis as well as electrical activities. We have developed a new "Brain Function Analyzer-BFA" which enabled monitoring of the following parameters continuously in real time from the surface of the cortex: ICP; tissue blood flow & volume; intramitochondrial NADH redox state; DC steady potential; electrocorticography; tissue temperature. The probes were assembled in a Brain Function Multiprobe (BFM) which was connected to the brain via the burr hole procedure used for ICP monitoring. Measurements were performed in 18 comatose patients after severe head injury (GCS < or = 8) who were monitored in the ICU for 48-72 hours. The basic concept of the multiparametric monitoring approach was proven to be practical in neurosurgical patients. Clear correlations were recorded between hemodynamic, metabolic, ionic and electrical activities under various treatments administered to the patients or after pathological events. Responses similar to cortical spreading depression and ischemic depolarization were recorded from a severely head injured patient.

Primary intramedullary spinal melanoma: diagnostic and treatment problems.

A 76-year old female patient with 9 year history of right mastectomy for an infiltrating ductal breast cancer and no evidence of recurrent nor metastatic disease, was admitted due to pain in the lower thoracic area radiating bilaterally to the posterior aspect of the chest wall at the same level, difficulties in micturition, urinary hesitancy, and progressive weakness of the lower limbs. Primary intramedullary spinal tumor was demonstrated by a MRI study of the spine, partially resected, and found to be a malignant melanoma on pathological study. Postoperative irradiation and administration of dexamethasone did not improve the neurologic status.

Cortical spreading depression recorded from the human brain using a multiparametric monitoring system.

The number of parameters (i.e., EEG or ICP-intracranial pressure) routinely monitored under clinical situations is limited. The brain function analyzer described in this paper enables simultaneous, continuous on-line monitoring of cerebral blood flow (CBF) and volume (CBV), intramitochondrial NADH redox state, extracellular K+ concentrations, DC potential, electrocorticography and ICP from the cerebral cortex. Brain function of 14 patients with severe head injury (GCS < or = 8), who were hospitalized in the neurosurgical or general intensive care unit was monitored using this analyzer. Leao cortical spreading depression (SD) has been reported in many experimental animals but not in the human cerebral cortex. In one of the patients monitored, spreading depression was observed. This is the first time that spontaneous repetitive cortical SD cycles have been recorded from the cerebral cortex of a patient suffering from severe head injury. Typical SD cycles appeared 4-5 h after the beginning of monitoring this patient. During the first 3-4 cycles the responses of this patient were very similar to the responses to SD recorded in normoxic experimental animals. Electrocorticography was depressed whereas extracellular K+ levels increased. The metabolic response to spreading depression was characterized by oxidation of intramitochondrial NADH concomitant to a large increase in CBF. During brain death, an ischemic depolarization, characterized by decrease in CBF and an irreversible increase in extracellular K+, was recorded.

Organization of layers II-III connections in human visual cortex revealed by in vitro injections of biocytin.

In the search for cortical mechanisms subserving psychological phenomena, a better understanding of human cortical circuitry is crucial. In this report we describe aspects of intrinsic connectivity of supragranular layers in human visual cortex, revealed by extracellular injections of the anterograde tracer biocytin in vitro. Human cortical slices were obtained from visual association cortex in the posterior-medial portion of the dorsal bank of the occipital lobe, removed during neurosurgical tumor ablations. Small iontophoretic injections of biocytin into layers II-III revealed intense Golgi-like staining of axonal projections emanating from the injection sites. Vertically descending axons are grouped in bundles 20 microns in diameter which are spaced 15 microns apart. Some of these axons enter the white matter and send long oblique and horizontal collaterals. The main horizontal spread of the axons could be observed in layers II-III and V. The bulk of projections extends to a distance of 1.5 mm in layers II-III and 1.1 mm in layer V. Few individual axons could be observed at greater distances. In contrast, layer IV is almost devoid of horizontal connections, forming a clear gap between supra- and infragranular layers. Axon collaterals in the infragranular layers project mostly in a descending oblique direction with long horizontal collaterals in lower layer VI.

New trend in neuroscience: low-power laser effect on peripheral and central nervous system (basic science, preclinical and clinical studies).

The present review summarizes findings in our continuing study of the use of low-power laser irradiation (LPLI) in the treatment of severely injured peripheral (PNS) and central nervous systems (CNS). The radiation method was proposed by Rochkind and has been modified over the last 13 years. LPLI in specific wavelengths and energy density maintains the electrophysiological activity of severely injured peripheral nerve in rats, preventing scar formation (at injury site) as well as degenerative changes in the corresponding motor neurons of the spinal cord, thus accelerating regeneration of the injured nerve. Laser irradiation applied to the spinal cord of dogs following severe spinal cord injury and implantation of a segment of the peripheral nerve into the injured area diminished glial scar formation, induced axonal sprouting in the injured area and restoration of locomotor function. The use of laser irradiation in mammalian CNS transplantation shows that laser therapy prevents extensive glial scar formation (a limiting factor in CNS regeneration) between a neural transplant and the host brain or spinal cord. Abundant capillaries developed in the laser-irradiated transplants, and was of crucial importance in their survival. Intraoperative clinical use of laser therapy following surgical treatment of the tethered spinal cord (resulting from myelomeningocele, lipomyelomeningocele, thickened filum terminale or fibrous scar) increases functional activity of the irradiated spinal cord. In a previous experimental work, we showed that direct laser treatment on nerve tissue promotes restoration of the electrophysiological activity of the severely injured peripheral nerve, prevents degenerative changes in neurons of the spinal cord and induces proliferation of astrocytes and oligodendrocytes. This suggested a higher metabolism in neurons and improved ability for myelin production under the influence of laser treatment. The tethering of the spinal cord causes mechanical damage to neuronal cell membranes leading to metabolic disturbances in the neurons. For this reason, we believe that using LPLI may improve neuronal metabolism, prevent neuronal degeneration and promote improved spinal cord function and repair. The possible mechanism of LPLI is investigated. Using electron paramagnetic resonance in cell culture models, we found that at low radiation doses, singlet oxygen is produced by energy transfer from porphyrin (not cytochrome as commonly assumed) which is known to be present in the cell. At low concentration, singlet oxygen can modulate biochemical processes taking place in the cell and trigger accelerated cell division. On the other hand, at high concentration, singlet oxygen damages the cell.(ABSTRACT TRUNCATED AT 400 WORDS)

Microsurgical anatomy of the pituitary gland and the sellar region. 1. The pituitary gland.

The microsurgical anatomy of the pituitary gland was studied on dissections of 250 cadaver sphenoidal blocks and on detailed operative reports of 266 patients who underwent transsphenoidal hypophysectomy (185 breast cancer patients and 81 patients with diabetic retinopathy). Whereas the various measurements (width, length, height, weight) and the structures of the two lobes of the pituitary gland were studied in cadavers, texture, consistency, color, and attachment to surrounding structures were best observed during surgical procedures. These latter aspects of the pituitary gland were correlated with the age, sex, and hormonal status of the patients. Variations in the shape, size, and appearance of the pituitary gland are frequent. Knowledge of such variations is important for a precise microsurgical approach to the sellar region.

Microsurgical anatomy of the pituitary gland and the sellar region. 2. The bony structures.

Measurements of the sella turcica (depth, length, width, volume, thickness of the floor, intraclinoid distance, length of tuberculum sellae) were made in cadaver sphenoid blocks, skulls, and in patients undergoing transsphenoidal surgery. Variations in the sphenoidal septae, sinuses and bulging of surrounding structures (carotid arteries and optic nerves) were studied. Results were compared with observations made during surgery and with data reported in the literature. Anatomic variations of the sella turcica and sphenoid sinus may complicate surgical intervention in the region of the sella turcica. However, these variations were never, in our experience, the cause for interruption of transsphenoidal surgery.

[Syndrome of redundant nerve roots of the cauda equina. Apropos of 2 cases]. / Le syndrome des racines redondantes de la queue de cheval. A propos de 2 cas.

Redundant nerve roots of the cauda equina (RNR) are considered to be extremely rare. This finding was reported for the first time in 1953 by Verbiest and since then several articles have being published on this subject. In an extensive review of the literature we have found 60 cases of RNR, 54 cases of which were operated including two new cases that we report in the present article. The RNR consist of elongated, tortuous and serpiginous nerve roots of the cauda equina. This disorder mainly affects males and the clinical history ranges from few months to three decades. The illness often start by a low back pain or sciatica associated or not with weakness or parasthesia of the lower limbs. There is sometimes a medullar claudication with gait ant sphincters disturbances. The electromyogram shows signs of chronic denervation and there is a high protein level in the CSF exam. X-rays of the lumbosacral spine show spondylarthrosis generally associated with a narrow spinal canal. The diagnosis is made by a lumbar myelogram which shows a partial or complete block of the column contrast. Serpentine defects suggest an arteriovenous medullar malformation, but the aortic angiogram is normal. At the opening of the dura-mater there is a sudden extrusion of the roots which are under pressure. The elongated roots are generally knotten or curled. One or several roots are very long but their diameter and aspect are normal. The treatment includes a decompressive lumbar laminectomy associated with a decompressive duroplasty.(ABSTRACT TRUNCATED AT 250 WORDS)

[Late post-traumatic syringomyelia. Discussion apropos an atypical case]. / Syringomyélie post-traumatique tardive? Discussion à propos d'un cas atypique.

Late post-traumatic syringomyelia is uncommon, the clinical signs appearing several years after severe trauma to the cervical spinal cord. It is due to progressive cavitation in the spinal cord. In the case reported here progress was atypical because there were no immediate neurological signs and the symptoms of syringomyelia developed only 3 weeks after injury. Several possibilities are open to discussion. Was the trauma responsible for the syringomyelia? Did it cause an aggravation of a pre-existing hydromyelia or were both lesions purely coincidental? A silicon tube draining the cavity in the cord to the subarachnoid space resulted in a real improvement in the neurological condition.

[Multiple intracranial aneurysms associated with primary hyperaldosteronism]. / Anévrysmes intracrâniens multiples associés à un hyperaldostéronisme primaire.

Multiple intracranial aneurysms have been reported in association with polycystic disease of the kidney, brain tumor, pituitary adenoma and coarctation of the aorta. We report the association of multiple aneurysms with primary hyperaldosteronism due to bilateral adrenal hyperplasia in an 18 year old left-handed man who presented with subarachnoid hemorrhage and arterial hypertension. We report the excellent outcome of this patient in spite of a difficult and surgical management. Ligation of all three intracranial aneurysms was performed after an extra-intracranial arterial bypass was done as a protective measure.

Hydrocephalus and headaches in Paget's disease of the skull: complete relief by ventriculo-atrial shunt.

A 76 year old patient with a long history of headaches was found to have Paget's disease and communicating hydrocephalus. There were (otherwise) no neurological or musculo-skeletal manifestations of Paget's disease, but moderate impairment of intellectual function was present. Treatment with disphosphonates did not bring any significant improvement, but three days following a ventriculo-atrial shunting procedure, the patient became headache-free for the first time in several years. In the literature, patients with hydrocephalus have been shown to respond quite unevenly to atrio-ventricular shunting, but in most instances the descriptions concerned advanced cases with well-established symptoms of dementia, ataxia and incontinence. Our case is reported to stress the importance of early diagnosis and management of hydrocephalus in Paget's disease for the prevention of widespread neurological dysfunction.