Third cervical nerve root and ganglion compression: clinical syndrome, surgical anatomy, and pathological findings.

OBJECTIVE: The aim of this study is to determine whether C3 nerve root and ganglion compression occurs and, if so, to provide a preliminary description of the associated clinical syndrome and surgical pathological findings. METHODS: The normal anatomy of the C2-C3 foramen was studied bilaterally in five fresh cadaver dissections and on 10 normal vertebral angiograms. Six patients were selected whose C3 dermatome sensory deficits resolved after C2-C3 facetectomy for C3 nerve root and ganglion decompression. RESULTS: Patients with C3 nerve root and ganglion compression presented with radiating pain, dysesthesias, and numbness referred to the C3 pain dermatome: the scalp area behind and over the ear, the pinna, and the angle of the mandible. At physical examination, the presence of analgesia/dense hypalgesia in the C3 pain dermatome established the diagnosis. Imaging studies were suggestive but inconclusive. Surgical pathological findings showed the C3 nerve root and medial portion of the ganglion flattened by C2-C3 facet and uncovertebral joint spurs and the lateral part of the ganglion stretched and flattened by C2-C3 arthrosis and the C2-C3 vertebral loop. Decompression was obtained by a complete facetectomy. Complications required four operations: recurrence, contralateral C3 root decompression, bilateral C2 nerve root decompression, and C2-C3 fusion. CONCLUSION: C3 nerve root and ganglion compression, although uncommon, does occur. It presents with radiating pain, dysesthesias, numbness, and a C3 dermatome sensory deficit. The associated clinical syndrome resolves after facetectomy and C3 root and ganglion decompression.

Central lumbar stenosis caused by ligamentum flavum: unilateral laminotomy for bilateral ligamentectomy: preliminary report of two cases.

Degenerative central lumbar stenosis has traditionally been considered to be a result of bony narrowing of the spinal canal. In two consecutive patients with degenerative central lumbar stenosis and complete myelographic blocks, the cauda equina was compressed by a thickened ligamentum flavum (cross-sectional area [CSA], > 150 mm2). This ligamentous stenosis occurred within bony canals of normal dimensions (anteroposterior diameter, interpediculate distance, interfacet distance, and CSA). High-resolution computed tomographic myelography was used to calculate quantitative values for the CSA, the length, and the volume of the lumbar ligamentum flavum. Excision of the thickened ligamentum flavum restored the dural sac to normal (CSA, 130-230 mm2), and both patients received relief from their symptoms. Unilateral laminotomy was used successfully to achieve bilateral ligamentectomy. Therefore, in a well-defined subgroup of patients with degenerative central lumbar stenosis, the dural sac can be decompressed by selective resection of the ligamentum flavum, and bilateral ligamentectomy can be performed via unilateral laminotomy.

Postoperative low-dose heparin decreases thromboembolic complications in neurosurgical patients.

Thromboembolic complications are a major cause of postoperative morbidity and mortality in the neurosurgical patient. Prophylaxis with lower extremity pneumatic compression boots (PCBs) reduces the incidence of lower extremity deep vein thrombosis (DVT) but has not been shown to affect the incidence of pulmonary embolism (PE). Prophylaxis with low-dose heparin has consistently reduced the incidence of both DVT and PE in studies on general surgical patients but has not been adopted for use in neurosurgery primarily for fear of causing catastrophic hemorrhage. We report on a series of 138 consecutive adult patients who underwent major neurosurgical procedures on a general neurosurgical service at our institution. Patients were treated with intraoperative PCBs and, starting on the morning of the first postoperative day, with a regimen of 5000 U of heparin administered subcutaneously twice daily. This treatment was continued until patients were fully ambulatory. PCBs were discontinued 24 hours after the first administration of heparin. None of the heparin-treated patients suffered postoperative hemorrhage. We compared this series with a control group of 473 adult patients who had previously undergone major neurosurgical procedures on the same neurosurgical service. These patients had been treated with intraoperative and postoperative PCBs alone. The control group had a 3.2% incidence of thromboembolic complications (15 of 473; eight DVT, seven PE). Prophylaxis with PCBs plus heparin significantly (P = 0.020) reduced the incidence of thromboembolic complications: no PCBs/heparin-treated patient exhibited clinical evidence of PE or DVT (0%, 0/138). We conclude that a combination of intraoperative PCBs and postoperative low-dose heparin is a safe and effective method by which to reduce thromboembolic complications in the neurosurgical patient.

Cervical disc herniation presenting as a mass lesion posterior to the odontoid process. Report of two cases.

The authors report two cases of herniated intervertebral disc presenting as a mass posterior to the odontoid process and causing myelopathy in previously healthy elderly women. The differential diagnosis of a mass at the craniovertebral junction is reviewed, and the implications of these cases are discussed.

Topography of C1 nerve- and trigeminal-evoked potentials in the ventrobasal complex of the cat thalamus.

In order to provide information pertaining to the C1 nerve representation in the thalamus, C1 nerve- and trigeminal-evoked potentials were recorded throughout the ventrobasal complex of the cat thalamus. Contralateral electrical stimulation of the C1 nerve and maxillary division of the trigeminal nerve elicited multiphasic positive-to-negative responses with mean maximum positive peak latencies of 2.2 ms and 2.7 ms, respectively. Ipsilateral stimulation failed to elicit a thalamic response. Construction of isopotential contour maps revealed that the foci of activity elicited by contralateral C1 nerve and trigeminal stimulation were located in the dorsolateral and ventromedial sections of ventroposterior medial nucleus (VPM), respectively.

Responses of cat C1 spinal cord dorsal and ventral horn neurons to noxious and non-noxious stimulation of the head and face.

Previous anatomical studies have shown that trigeminal and cervical afferent nerve fibers project to the upper cervical segments of the spinal cord. To determine the response properties of neurons in the upper cervical spinal cord, we studied the response of C1 dorsal and ventral horn cells to electrical and graded mechanical stimulation of the face, head and neck in anesthetized cats. Neurons were classified as low-threshold-mechanoreceptive (LTM), wide-dynamic-range (WDR), nociceptive-specific (NS) or unresponsive, based on their responsiveness to graded mechanical stimulation. Extracellular single unit recordings were obtained from 118 neurons excited by cervical (24), trigeminal (39) or both cervical and trigeminal (55) stimulation and from 24 neurons unresponsive to peripheral stimulation. Based on neuronal mechanical response properties, 52.2% of the responsive neurons were classified as LTM, 35.9% as WDR and 11.9% as NS. WDR neurons exhibited more convergence and had larger receptive fields than either NS or LTM neurons. WDR and NS neurons had longer first spike latencies than LTM neurons at all tested sites. Only WDR neurons were found to project to the contralateral caudal thalamus. Within C1, LTM neurons were located primarily in laminae III and IV, WDR neurons in lamina V and NS neurons in laminae VII and VIII. These data suggest that some neurons in the first cervical segment of the spinal cord receive convergent input from trigeminal and cervical pathways and may be involved in mediating orofacial and cranial pain.

Clipping of an aneurysm 20 years after encasement with methyl methacrylate. Case report.

A variety of agents have been used to coat aneurysms as an alternative to clipping. These agents were employed more frequently prior to the routine use of the operating microscope and the presently available variety of aneurysm clips. One such coating agent is methyl methacrylate. This report describes a patient with an anterior communicating aneurysm that rebled 20 years after being encased in methyl methacrylate. At operation, the pulsating aneurysm had eroded the adjacent layer of methyl methacrylate, creating a small intervening space. This space allowed removal under the microscope (with a high-speed air drill and a diamond bit) of the methyl methacrylate from the anterior cerebral arteries and aneurysm, exposing it for definitive clip placement. The feasibility of clipping encased aneurysms is discussed.

C2 and C3 pain dermatomes in man.

This report defines the C2 and C3 pain dermatomes by the distribution of: the hypalgesia clearing after surgical root decompression; the dysaesthesias produced by electrical root stimulation; and the hypalgesia produced by anaesthetic root block. The C2 pain dermatome, so defined, consists of an occipital parietal area 6-8 cm wide, ascending paramedially from the subocciput to the vertex. The C3 pain dermatome is a craniofacial area including the scalp around the ear, the pinna, the lateral cheek over the angle of the jaw, the submental region and the lateral and anterior aspects of the upper neck. These C2 and C3 pain dermatomes do not overlap and are smaller than the C2 and C3 tactile dermatomes described in the literature.

Preproenkephalin upregulation in nucleus caudalis: high and low intensity afferent stimulation differentially modulate early and late responses.

Nucleus caudalis expression of preproenkephalin mRNA changes following lesions depleting small-caliber primary afferent fibers and after stimulation of trigeminal afferents at different intensities. Animals treated neonatally with capsaicin display reduced preproenkephalin gene expression in nucleus caudalis neurons. Stimulation of normal animals at low intensities enhances preproenkephalin expression in a bimodal temporal pattern. High intensity stimulation is effective only at later time points in normal animals, but it causes both early and late effects on preproenkephalin expression when applied to animals neonatally lesioned with capsaicin. Transsynaptic regulation of preproenkephalin expression in pain-modulating areas of the nucleus caudalis of the trigeminal nerve thus depends on the specific type of primary afferent input. The rapid responses noted after selective large fiber stimulation appear to be suppressed by coactivation of small caliber fibers. Later responses appear less influenced by the quality of the eliciting afferent stimulus.

Contralateral trigeminal dysaesthesias associated with second cervical nerve compression: a case report.

This 70-year-old woman presented with a left C2 solitary metastatic lesion producing ipsilateral occipital pain associated with contralateral fronto-orbital dysaesthesias. Examination revealed analgesia in the left C2 dermatome and hyperaesthesia in the right forehead. These symptoms and findings resolved following a course of radiation therapy to the C2 metastasis. Ipsilateral trigeminal dysaesthesias produced by cervical lesions have been described, however, contralateral cervicogenic trigeminal dysaesthesias have not. Relevant experimental data are analysed; neural pathways are suggested by which a cervical lesion, especially at C2 or C3, may produce trigeminal dysaesthesias referred ipsilaterally or contralaterally.

Entrapment of the C2 root and ganglion by the atlanto-epistrophic ligament: clinical syndrome and surgical anatomy.

Two cases of progressive, occipital lancinating pain and dysesthesias associated with a sensory deficit of the C2 dermatome are presented. Symptoms were relieved, and C2 sensory function restored by releasing a hypertrophied atlanto-epistrophic ligament entrapping the C2 root and ganglion. The normal anatomy and abnormal surgical findings are described. C2 entrapment by the atlanto-epistrophic ligament is discussed in reference to other C2 lesions causing occipital pain. We conclude that some patients whose progressive occipital pain is accompanied by a C2 sensory deficit are suffering from entrapment of the C2 root and ganglion amenable to surgical decompression.

Acute presentations of syringomyelia. Report of three cases.

Three unusual cases are reported in which communicating syringomyelia presented acutely. The first patient presented with paraplegia, the second with acute respiratory distress secondary to bilateral vocal cord paralysis, and the third with symptoms of acute brain-stem ischemia. Each patient had a communicating spinal cord syrinx associated with a posterior fossa and foramen magnum region anomaly (a huge posterior fossa arachnoid cyst in one and Chiari malformations in two). The mechanisms of craniospinal pressure dissociation and hindbrain herniation are discussed, along with other reported emergency presentations of syringomyelia.

A temporal approach to anterior communicating artery aneurysms. Technical note.

As an alternative to approaching anterior communicating artery (ACoA) aneurysms through the frontal fossa, either parasagittally or laterally (pterional, gyrus rectus approach), this report describes an approach to ACoA aneurysms through the temporal fossa. The main advantages of this temporal technique are that it requires less brain retraction, gives better surgical orientation, gains control of both A1 segments before disturbing the aneurysm, and involves minimal resection of brain tissue. This temporal approach has recently been used by the author in 20 consecutive operations for ACoA aneurysms in preference to the gyrus rectus approach.

Distribution of 10B after infusion of Na210B12H11SH into a patient with malignant astrocytoma: implications for boron neutron capture therapy.

If a sufficient concentration of the stable isotope 10B is introduced into a neoplasm, radiation therapy can be effected by short-range heavy charged particles from the disintegration of 10B by slow neutrons. Brain tumors were irradiated postoperatively by Hatanaka and co-workers in Japan using a 1 to 2 hour intraarterial infusion of 10B-enriched Na2B12H11SH (Na210B12H11SH) before exposure of the tumor-bearing area of the brain to slow neutrons from a 100 kilowatt nuclear reactor. The clinical outcome of such boron neutron capture therapy has been favorably impressive in some patients, but its efficacy in brain tumors needs improvement. In our study, a terminally ill patient with malignant astrocytoma was infused intravenously with Na210B12H11SH for 25 hours. The postmortem distribution of 10B in unfixed, frozen, tumor-bearing brain and spinal cord tissues was studied by comparing representative cryostat sections of these specimens with neutron-induced heavy charged particle radiographs of the same sections. Preferential accumulation of 10B was observed in the tumor, with relatively little accumulation of 10B in the parenchyma of the central nervous system.

Evidence for leucine-enkephalin immunoreactive neurons in the medulla which project to spinal cord in squirrel monkey.

Rhodamine-labeled latex microsphere injections were combined with horseradish peroxidase immunohistochemistry in squirrel monkeys to reveal neurons in the medullary raphe and medial reticular formation which projected to spinal cord and were positive for leucine-enkephalin-like immunoreactivity. Double-labeled cells were found primarily in nucleus raphe magnus, the reticular nucleus magnocellularis, and the lateral reticular nucleus. These results provide evidence for a descending projection from enkephalin-containing cells of the rostral ventral medulla, a region which has been strongly implicated in antinociception.

Human trigeminal root evoked potentials during differential retrogasserian thermal and chemical rhizotomy.

Human trigeminal root evoked potentials have been recorded using signal averaging techniques during radiofrequency trigeminal rhizotomy and lidocaine blocks in patients with trigeminal neuralgia. Both short and long latency trigeminal root potentials have been recorded which appear to represent fast- and slow-conducting fiber activity respectively. Long latency trigeminal root potentials appear in recordings at the noxious threshold as perceived by the awake patient and are relatively selectively abolished in a reversible fashion by lidocaine block and irreversibly by radiofrequency heat. Evaluation of these trigeminal root potentials provides an objective assessment of the results of pain surgery directed at differential destruction of slow-conducting fiber activity.

Morphology of pontomedullary raphe and reticular formation neurons in the brainstem of the cat: an intracellular HRP study.

In order to understand better the anatomical substrates underlying processing of sensory information, the cytoarchitecture of neurons in the pontomedullary raphe and reticular formation was investigated following intracellular injections of horseradish peroxidase in the cat. Raphe cells studied were located in the nucleus raphe magnus, nucleus raphe obscurus, and nucleus raphe pallidus. The most prominent type had a smooth, oval cell body and oval dendritic tree with dendrites extending laterally into the adjacent reticular formation. Two other raphe cell types, large cells with a dorsoventral orientation of both cell body and dendritic tree, and very small cells, were rarer. The primary dendritic orientation lay in the coronal plane for all three raphe cell types. Wispy, straight, or clublike spines were located on more distal regions of dendrites, although we also found spineless dendrites. Raphe cells lying near longitudinal fiber pathways exhibited bundling of dendrites around the passing axon fascicles. Reticular formation cells studied were located in the nucleus gigantocellularis, nucleus magnocellularis, nucleus paragigantocellularis dorsalis, and nucleus reticularis paramedianus. Two morphological types were found on the basis of dendritic branching patterns: sparsely branched and densely branched. Most reticular formation cells had round dendritic trees as viewed in the coronal plane and polygonal cell bodies that were medium to large in size. There was no correlation between reticular formation cell morphology and nuclear location. Spines were more common on the densely branched cells, but for both reticular cell types they were usually absent from cell bodies and proximal dendrites. Thus, by using the criteria of dendritic branching and arbor shape along with distance from the midline it was possible to identify raphe cells as distinct from reticular formation cells. In contrast, no morphological characteristics were found that would differentiate cells in the two major median reticular formation nuclei, gigantocellularis and magnocellularis.

Amygdalospinal projections in the cat.

Spinal cord injections of rhodamine-labeled fluorescent latex microspheres in the cat resulted in retrograde labeling of a dense, well-defined group of neurons within the central nucleus of the amygdala and a modest number of neurons in the medial nucleus. Amygdalospinal neurons were found to be large cells of variable shape and orientation that were distributed bilaterally with an ipsilateral predominence.