Substance P and somatostatin metabolism in sympathetic and special sensory ganglia in vitro.

Mechanisms regulating the content of the putative peptide transmitters, substance P and somatostatin, were examined in several neuronal populations in culture. Substance P levels increased more than 25-fold within 48 h in sympathetic neurons in the explanted rat superior cervical ganglion, and remained elevated for 4 weeks. Identity of the peptide was authenticated by combined high pressure liquid chromatography-radioimmunoassay. Veratridine prevented the increase of substance P in vitro, and tetrodotoxin blocked the veratridine effect, suggesting that sodium ion influx and membrane depolarization prevent peptide elevation. Veratridine (or potassium)-induced membrane depolarization released substance P into the culture medium through a calcium-dependent process. Consequently, at least some veratridine effects are attributable to release and subsequent depletion of ganglion peptide. However, the inhibitory effects of veratridine were far greater than could be accounted for by the quantity of peptide released, suggesting a separate influence on net synthesis (synthesis less catabolism) of substance P. Viewed in conjunction with previous in vivo studies, our observations suggest that trans-synaptic impulses, through the mediation of postsynaptic sodium flux, release substance P from sympathetic neurons and also regulate intracellular peptide metabolism. To determine whether the processes regulating substance P in sympathetic neurons reflect generalized mechanisms, a different peptide, somatostatin, was examined in sympathetic neurons; moreover, substance P was examined in a different neuronal population, special sensory neurons in the nodose ganglion. Substance P levels increased significantly in both sympathetic and sensory neurons after explantation, and somatostatin levels increased in sympathetic neurons. In each instance, the increase was dependent upon the presence of the calcium ions. Moreover, these increases were all prevented by veratridine, in a tetrodotoxin-sensitive manner. Our observations suggest that common regulatory mechanisms govern peptide transmitter metabolism in diverse neuronal populations.

Substance P levels differ in sympathetic target organ terminals and ganglion perikarya.

Regulation of the putative neurotransmitter, substance P (SP), was examined in the rat iris and pineal, targets of the peptide-containing superior cervical sympathetic ganglion (SCG). Decentralization (denervation) of the SCG, which is known to increase ganglion SP, did not alter the peptide in either target. Conversely, surgical or pharmacologic (6-hydroxydopamine) ablation of the SCG actually increased SP in both targets. Moreover, destruction of the trigeminal sensory innervation reduced iris SP to virtually blank levels. Finally, trigeminal ablation abolished the rise in iris SP subsequent to sympathetic destruction with 6-hydroxydopamine. Our observations suggest that sympathetic terminals in targets, in contrast to ganglion perikarya and processes, contain negligible quantities of SP. Consequently, SP may not be transported from ganglion to periphery, but may serve an intraganglionic function. Our studies also suggest that sympathetic terminals modulate sensory peptidergic innervation of the iris.

Retractor for lumbar microdiscectomy: technical note.

The authors describe a modification of an existing lumbar spine retractor for use in lumbar microdiscectomy.

Simple decompression and occasional microsurgical epineurolysis under local anesthesia as treatment for ulnar neuropathy at the elbow.

Decompression of the ulnar nerve in the cubital tunnel will reverse ulnar neuropathy at the elbow in most patients. We believe that operating under local anesthesia has allowed us to identify those few patients who will not respond to simple decompressive surgery. Among the 20 cases of ulnar neuropathy managed in this fashion, intraoperative motor-sensory improvement occurred after simple decompressive surgery in 16. Four patients who failed to improve after cubital tunnel decompression underwent microsurgical epineurolysis immediately thereafter, under the same local anesthetic, with prompt improvement. Local anesthesia and microsurgical epineurolysis seem to be useful adjuncts to simple decompressive surgery for ulnar neuropathy.

Arachnoid cysts of the posterior fossa.

Arachnoid cysts of the posterior fossa are an uncommon clinical entity. The two cases presented in this review were evaluated without vertebral angiography. We think that the development of magnetic resonance imaging may obviate the need for angiography in selected cases.

Symptomatic Arnold-Chiari malformation: review of experience with 22 cases.

Twenty-two patients with closed myelomeningoceles, shunted hydrocephalus, and symptomatic Arnold-Chiari malformations were studied retrospectively. Seventeen of the 22 patients were aged 6 months or younger; five patients were aged 3 to 23 years. Patients in the younger group presented with stridor, apnea, and/or feeding difficulty; those in the older group presented with hemiparesis, quadriparesis, oscillopsia, nystagmus, or opisthotonos. Fourteen of the 17 younger patients underwent surgical decompression of the Arnold-Chiari malformation: 10 within 18 days following the onset of symptoms and four on Day 19 or later. Of the 10 infants with early treatment, five eventually died secondary to continued symptoms and five survived. Of those surviving, three were asymptomatic and two had continuing symptoms but were improved over their preoperative state. Among the four patients undergoing surgery later, two died, one had lessening of stridor, and one had complete relief of symptoms. Of the three infants not undergoing decompression, two died and one eventually became asymptomatic. All five of the older patients underwent decompression and all had complete resolution of their preoperative symptoms and signs. The authors conclude that while decompression of a symptomatic Arnold-Chiari malformation may be effective in children and adults, this treatment does not always improve the clinical condition of infants. This may be the result of ischemic/hypoxic effects on the infant's brain stem, which may not be organized normally at birth.

Cottonoid as an acoustical marker for intraoperative ultrasound scanning. Technical note.

The authors demonstrate the use of cottonoid as a marker for ultrasound localization of a subcortical tumor.

Leptomeningeal spread of intramedullary spinal cord tumors. Report of three cases.

Three patients with intramedullary spinal cord tumors and secondary leptomeningeal spread of their tumors are presented. Two patients had astrocytomas and one had a ganglioglioma. Two tumors were located in the cervical spinal cord and one within the thoracic spinal cord. Review of the past and recent literature shows leptomeningeal dissemination of spinal cord tumors to be relatively rare, but it should be suspected and investigated in any patient whose condition deteriorates following removal of a spinal cord neoplasm.

Venous air embolism after craniotomy closure: tension pneumocephalus implicated.

The authors present a case of venous air embolism occurring immediately upon skin closure after craniotomy in the prone position. This 5-year-old patient had a third ventricle tumor resected with bipolar cautery via a frontal trans-collosal approach into the lateral ventricle and through the foramen of Monroe. Doppler monitoring was utilized during the case since the patient's head was extended upwards in 10 degrees reverse Trendelenburg position. No air was detected during the operation. The ventricles were filled with saline presumably displacing air, prior to dural closure. However, with an increase in nitrous oxide from 55 to 68% prior to skin closure, venous air embolism was subsequently detected by Doppler and confirmed by end-tidal/arterial pCO2 gradient. The authors speculate that tension pneumocephalus caused the venous air embolism and describe the probable route of entry into the venous system.

Migration of a ventriculoperitoneal shunt into the pulmonary artery.

Ventriculoperitoneal (VP) shunts have been reported to migrate into a number of unusual locations within the abdomen, chest, and pelvis. We report a case in which a documented, correctly placed VP shunt subsequently migrated to an intravascular location. This intravascular migration led to malposition of the shunt tubing within the pulmonary artery. Attempts to remove the catheter via a postauricular incision were complicated by arrhythmias induced by traction on the shunt tubing. Eventual removal of the shunt was accomplished in stages, through the use of an intravascular, radiographically guided snare, introduced through the femoral vein.

One-stage meningomyelocele closure and ventriculoperitoneal shunt placement.

Thirteen myelodysplastic neonates were observed to have birth head circumferences below the 90th percentile but ventriculomegaly on preoperative computed tomograms. These infants all required later shunting for hydrocephalus. We then began performing a one-stage procedure of meningomyelocele closure and shunt insertion in all neonates with ventriculomegaly on preoperative computed tomograms without regard to head circumference. Seventeen of 24 additional patients have had the one-stage procedure; 4 have required later shunting; 1 shunt infection (6%) was encountered. We conclude that neonatal head circumference does not predict hydrocephalus, and that ventriculomegaly on preoperative computed tomograms identifies neonates who will require shunting.

Granuloma annulare: a rare occipital lesion in infants and children.

Subcutaneous granuloma annulare is a rare scalp lesion that occurs in infants and children. Occurrence in the occipital region, absence of bone involvement, slow growth, and foci of necrosis of collagen surrounded by palisading granulomatous inflammation are characteristic of this lesion. Although the cause remains unknown, it is not infectious and is more likely due to a defect in cell-mediated immunity. The prognosis after excision is excellent. Increased awareness that this peculiar granulomatous lesion can rarely occur in the soft tissue of the occipital region will help prevent confusion with neoplastic or infectious processes.

Surgical repair of aneurysms of the posterior inferior cerebellar artery--a clinical series.

Aneurysms of the posterior inferior cerebellar artery are relatively rare. Fourteen such aneurysms (10 vertebral, 4 peripheral) are reported, and their clinical presentation, surgical therapy, and outcome are discussed. All 14 patients had suffered a subarachnoid hemorrhage; 93% (n = 13) underwent direct clipping of the aneurysm while 7% (n = 1) underwent coating of the aneurysm. Two patients died in the perioperative period (one from vasospasm and one from rebleeding). Full activity was achieved by all but one (92%) of the remaining patients in extended follow-up.

Functional neurosurgery for psychiatric disorders: a historical perspective.

Functional neurosurgery for psychiatric disorders ('psychosurgery') has a colorful, and sometimes dubious, history. From the time of the first operations in 1935 to today, its usefulness has been overshadowed by doubts and ethical questions. Psychosurgery became popular in the 1940s and early 1950s, especially in the United States. Its main indications were for intractable mental illness, in particular, depression, anxiety, and obsessive-compulsive disorders. However, its side effects, especially the 'frontal lobe syndrome', led to the need for more refined surgical approaches; the most important of these was the use of stereotaxis. Cingulotomy, subcaudate tractotomy, limbic leucotomy, and anterior capsulotomy are generally the stereotactic treatments of choice today. Indications and postoperative sequelae vary slightly across treatments. The indications remain as affective, anxiety, and obsessive-compulsive disorders. Despite approval by the United States Department of Health, Education, and Welfare in 1978, psychosurgery is still not a common treatment. This low acceptance is perhaps due to continued concern over ethical problems and inadequate reporting of outcomes.

The significance of ventriculomegaly in the newborn with myelodysplasia.

Hydrocephalus occurs in 69% to 92% of the meningomyelocele population, but rarely becomes manifest until after the meningomyelocele is closed. Ventriculomegaly is common at birth, even in neonates without overt hydrocephalus. Thus, palpating the anterior fontanel and cranial sutures and measuring the head circumference may be misleading. We report a means of identifying spina bifida neonates who will subsequently develop hydrocephalus. Dubowitz gestational age, birth weight, birth head circumference, head circumference percentile, and the lateral ventricular ratio (LVR) from ultrasonograms were analyzed for each of 25 neonates with meningomyelocele. The mean head circumference percentile was 47.7 +/- 7.7 SE (range: less than 5 to greater than 95). Ventriculomegaly, however, defined by an LVR of greater than 0.32, was present in all but 2 of the neonates. Pearson's correlation test showed that only one-third of the elevated LVRs could be explained by the head circumference. Later ventricular shunting was eventually required in all but 3 infants. We concluded that (1) clinical examination of the myelodysplastic neonate usually does not reveal evidence of hydrocephalus and (2) ventriculomegaly on ultrasonography predicts the later development of hydrocephalus following meningomyelocele closure.

Interactions between the sympathetic and sensory innervation of the iris.

The interaction between peptidergic, sensory nerves and sympathetic fibers was examined in the rat iris. The putative peptide neurotransmitter, substance P, was used as an index of the sensory innervation, because the peptide is exclusively localized in the iris to trigeminal sensory fibers. Extirpation of the sympathetic, superior cervical ganglion resulted in an increase in iris content of substance P-like immunoreactivity (henceforth SP), suggesting that sympathetic terminals influence the peptidergic sensory innervation of the iris. The increase in iris peptide after sympathetic ganglionectomy was reversed by implantation of sympathetic ganglia into the anterior chamber of the eye. Pharmacological stimulation or blockade of sympathetic nerve impulse activity and pharmacological blockade of sympathetic axonal transport did not alter iris peptide, suggesting that these procedures did not mediate the sympathetic-sensory interaction. However, injection of nerve growth factor (NGF) systemically or into the anterior chamber increased iris peptide, reproducing the effects of ganglionectomy. Conversely, injection of antiserum to NGF (anti-NGF) into the anterior chamber decreased iris SP suggesting that endogenous trophic protein normally regulates sensory peptide. The effects of anti-NGF were transitory; iris peptide returned to normal after cessation of treatment. Consequently, anti-NGF administration apparently did not lead to sensory neuron destruction, but rather altered either the number of sensory fibers in the iris or the amount of peptide per fiber. Finally, injection of anti-NGF into the anterior chamber reversed the effects of sympathetic ganglionectomy, suggesting that NGF may mediate the sympathetic-sensory interaction. Our observations suggest that competition for target NGF may result in reciprocal regulation of the iris sympathetic and sensory innervation.

Contraindications to lumbar puncture as defined by computed cranial tomography.

Papilloedema is not always an adequate predictor of potential complications from lumbar puncture, and many clinicians are using computed tomography (CT) before lumbar puncture in an effort to identify more accurately the "at risk" patient. This paper identifies the following anatomical criteria defined by CT scanning that correlate with unequal pressures between intracranial compartments and predispose a patient to herniation following decompression of the spinal compartment: lateral shift of midline structures, loss of the suprachiasmatic and basilar cisterns, obliteration of the fourth ventricle, or obliteration of the superior cerebellar and quadrigeminal plate cisterns with sparing of the ambient cisterns. These criteria should be considered to be contraindications to lumbar puncture.

An increase in infant cranial deformity with supine sleeping position.

Abnormalities of the occipital cranial suture in infancy can cause significant posterior cranial asymmetry, malposition of the ears, distortion of the cranial base, deformation of the forehead, and facial asymmetry. Over the past 2 years, we have noted a dramatic increase in the incidence of deformation of the occipital skull in our tertiary referral center. Our patient referral base has not changed appreciably over the past 5 years and patients have been referred from the same primary practitioner base. The timing of this increase correlates closely with the acceptance in our area of recommended changes in sleeping position to supine or side positioning for infants because of the fear of sudden infant death syndrome (SIDS). A total of 51 infants with occipital cranial deformity, with a mean age of 5.5 months at presentation, have been evaluated and treated by a single craniofacial surgeon in the 16-month period from September 1993 to December 1994. Older infants were treated with continuous positioning by the parent keeping the infant off the involved side. Younger infants and those with poor head control were treated with a soft-shell helmet. Mean timing of initial diagnosis and start of treatment was 5.5 months. Mean duration of helmet for positional treatment was 3.8 months. To date, only 3 of 51 patients have required surgical intervention, and other patients demonstrated spontaneous improvement of all measured parameters. Follow up has ranged from 8 to 24 months. We believe that most occipital plagiocephaly deformities are deformations rather than true cranio-synostoses. Despite varying amounts of suture abnormality evidenced on computed tomographic scans, most deformities can be corrected without surgery. In cases where progression of the cranial deformity occurs, despite conservative therapy, surgical intervention should be undertaken at approximately 1 year of age. The almost universal acceptance in the State of North Carolina of positioning neonates on their backs to avoid SIDS, may well increase the incidence of these deformities in the future.

Prenatal diagnosis and pediatric neurosurgery.

Advances in realtime ultrasound imaging and a greater availability of high-quality ultrasound equipment have resulted in an increased number of congenital abnormalities being diagnosed prenatally in the last 10-15 years. In addition, testing for maternal serum alpha-fetoprotein, beta-human chorionic gonadotropin, and serum unconjugated estriol has allowed for more sensitive screening for congenital abnormalities. In response to this, in 1989 the Prenatal Diagnosis and Treatment Center was established at our institution to coordinate the care of fetuses and newborns with congenital malformations and to provide alternatives for the parents should the fetus not be carried to term. From January 1990 through June 1993, our group diagnosed 50 singleton pregnancies with various types of central nervous system disorders by the methods outlined above. Thirty-seven fetuses were diagnosed with neural tube defects. Of these, 5 were anencephalic and 1 had an encephalocele. The remaining 31 fetuses had meningomyeloceles with associated hydrocephalus. Of these 31, 18 fetuses were terminated prior to the age of viability as a result of our counseling and 13 fetuses were brought to term. Of the remaining 13 fetuses, 8 had hydrocephalus and 5 had various other diagnoses. Three of the eight hydrocephalic fetuses were either terminated, stillborn, or died following birth. Of the other 5 fetuses with hydrocephalus, 3 had shunts placed, 1 was followed with normal head growth, and 1 had normal ventricular size at birth. Using the methods available, the accuracy of diagnosis is very high, with only 1 fetus in this series being incorrectly diagnosed. Additionally the advantages of being able to counsel the parents regarding their unborn child allows them to make informed decisions. Accurate prenatal diagnosis plays a major role in the care of the fetus and in counseling parents prenatally for pediatric neurosurgical problems.