Temporary abolition of pain in man.

In eight patients with intense chronic cutaneous pain, sensory nerves or roots. supplying the painful area were stimulated. Square-wave 0.1-millisecond pulses at 100 cycles per second were applied, and the voltage was raised until the patient reported tingling in the area. During this stimulation, pressure on previously sensitive areas failed to evoke pain. Four patients, who had diseases of their peripheral nerves, experienced relief of their pain for more than half an hour after stimulation for 2 minutes.

Pre-trigeminal neuralgia.

Eighteen patients who subsequently developed typical trigeminal neuralgia experienced a prodromal pain termed "pre-trigeminal neuralgia." These patients described their prodromal pain as a toothache or sinusitis-like pain lasting up to several hours, sometimes triggered by jaw movements or by drinking hot or cold liquids. Typical trigeminal neuralgia developed a few days to 12 years later, and in all cases affected the same division of the trigeminal nerve. Six additional patients experiencing what appeared to be pre-trigeminal neuralgia became pain-free when taking carbamazepine or baclofen. Recognition of pretrigeminal neuralgia makes it possible to relieve the pain with appropriate medications and avoid unnecessary irreversible dental procedures.

Deafferentation pain after posterior rhizotomy, trauma to a limb, and herpes zoster.

After incisional or alcoholic destruction of trigeminal posterior rootlets, constant dysesthesias of major degree referred to some part of the markedly denervated zone develop in 5 to 15% of the patients. The full severity may not appear for weeks or months. There is no allodynia or hyperpathia of the denervated zone. Bulbar trigeminal tractotomy with sparing of touch sensation produces severe dysesthesias in a tiny percentage of the patients, as does selective destruction of pain fibers by radiofrequency heating or glycerol. Spinal posterior rhizotomy elicits in less than 4% a lasting dysesthesia entirely different in temporal sequence, locus, and type of pain: (a) it tends to be maximal early after operation and to improve, (b) the spontaneous pain is accompanied by severe allodynia, and (c) the pain is usually referred beyond the margins of the insentient (rhizotomized) zone and may even be referred to the corresponding area on the opposite side. Sindou's "selective posterior rhizotomy," i.e., cutting of the small fiber lateral component of each rootlet as it enters the cord, has not given rise to dysesthesias. These do occur briefly in 50% of the cases following spinal ganglionectomy, the sensations being referred to the dermatomal segment of the ganglion in question. The secondary afferent neurons in the mesencephalic, principal, oral, and interpolar nuclei for the trigeminal posterior roots have no counterpart in the spinal cord for the spinal posterior roots. We suggest that the explanation for the fact that neither trigeminal neuralgia nor trigeminal anesthesia dolorosa have a spinal clinical counterpart is related to the as yet unexplained special functions of the elaborate trigeminal secondary afferent neuronal apparatus.(ABSTRACT TRUNCATED AT 250 WORDS)

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.

Dangerous rises in blood pressure upon heating of trigeminal rootlets; increased bleeding times in patients with trigeminal neuralgia.

During radiofrequency (RF) heating of trigeminal rootlets, we regularly measured blood pressure rises to 250 to 300 mm Hg, confirming two previous reports. We also found abnormally increased bleeding times in 12% of 127 patients awaiting operation for trigeminal neuralgia. These two facts probably explain 6 fatalities and 2 lasting hemiplegias from intracranial bleeding unrelated to vascular puncture by the needle electrode during RF procedures for trigeminal neuralgia. We recommend correction of the abnormal bleeding time and control of the blood pressure rises by i.v. sodium nitroprusside.

Treatment of trigeminal neuralgia and other facial pains by retrogasserian injection of glycerol.

Håkanson's treatment of trigeminal neuralgia by injecting 0.2 to 0.4 ml of glycerol into the cerebrospinal fluid in Meckel's cave was carried out in 27 patients with trigeminal neuralgia, 3 with atypical facial neuralgia, and 1 with post-traumatic facial neuralgia. Minor modifications of his technique are described based on our finding of a greater pain and sensory loss upon injection than he noted. We present evidence that glycerol is more toxic than its cryoprotectant effect would intimate and that it selectively eliminates those components of the compound action potential in the trigeminal rootlets customarily associated with pain. We conclude that the method is probably going to be an improvement over radiofrequency heating for the treatment of trigeminal neuralgia in many situations.

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.

Relative cerebral glucose metabolism evoked by dental-pulp stimulation in the rat.

Electrical stimulation of dental pulp is widely acknowledged to produce a sensation that is predominantly or exclusively noxious in character. The authors report the pattern of local cerebral glucose utilization evoked by dental-pulp stimulation in the barbiturate-anesthetized rat, using the [14C]2-deoxyglucose method of Sokoloff. Autoradiographs were prepared from cryostat-cut brain sections of animals given an intravenous pulse of [14C]2-deoxyglucose and sacrificed after 45 minutes of continuous bipolar stimulation of the incisor tooth pulp. Areas of high optical density on the autoradiographs identified brain regions where glucose consumption, and hence functional activity, was maximal. Stimulus-related increases in glucose utilization were seen ipsilaterally in an uninterrupted column from the lower levels of trigeminal nucleus caudalis to the rostral extent of the main sensory nucleus. Mandibular incisor pulp stimulation yielded increased deoxyglucose uptake in relatively restricted dorsal portions of the nuclei, while maxillary pulp stimulation produced a more extensive area of uptake ventrally. Elevated deoxyglucose uptake was also seen in the contralateral ventrobasal thalamus and sensory cortex with maxillary, but not mandibular, pulp stimulation. No changes in metabolic activity were detected in extralemniscal or limbic structures. These initial results suggest that the [14C]2-deoxyglucose method may be a useful means of mapping central structures involved in nociception.

Conducted somatosensory evoked potentials during spinal surgery. Part 2: clinical applications.

In 27 patients undergoing laminectomy, spinal cord function was monitored by epidural bipolar recordings of conducted spinal somatosensory evoked potentials (SEP's) across the laminectomy site, with calculation of spinal conduction velocity (CV). In control cases without myelopathy, the CV remained relatively constant (+/- 3%) even during prolonged operations, despite markedly changing levels of anesthesia. Acute CV changes were detected intraoperatively in three cases: these patients displayed improvement after extramedullary (Case 1) and intramedullary decompression (Case 2), and deterioration after direct unilateral dorsal column injury (Case 3). These intraoperative CV alterations correlated postoperatively with changes in the neurological examination. Although a unilateral lesion confined to the dorsal column abolished the ipsilateral SEP in Case 3, complete anterior quadrant lesions did not consistently change the CV (Case 4). This further suggests that the SEP is generated entirely by ipsilateral dorsal column activation. Accurate measurement of this dorsal column conduction velocity across the operative field provides a very sensitive means of monitoring spinal cord function during operations for neurosurgical spinal lesions.

Cancer pain relieved by long-term epidural morphine with permanent indwelling systems for self-administration.

Clinical trials for abatement of intractable pelvic cancer pain were conducted in two patients, each electing surgical implantation of one of two indwelling catheter systems for administration of morphine into the spinal epidural space. Both systems, one consisting of a partially indwelling Broviac catheter, and the other, completely indwelling, consisting of a morphine reservoir connected to a shunt pump and on-off Hakim valve assembly, permitted the patients to return home where they could self-administer epidural morphine. Each patient reported that 2 mg of epidural morphine provided 8 to 12 hours of pain relief at a level of superior to their previous narcotic medication. On a regimen of 2 mg of epidural morphine administered twice daily, both patients experienced analgesia for 6 months, unaccompanied by alterations in sensory, motor, or cognitive functioning, and with a little drug tolerance reaction.

Pain--old and new methods of study and treatment.

In the last 5 years several remarkable methods for localizing precisely a wide range not only of specific motor and sensory functions but as well of more complex mental phenomena in the domain of cognitive functions have been demonstrated to evoke sharply localizable responses. In pain, positron emission tomography (PET) scanning has been used to show that the anterior gyrus cinguli is an integral component of the pain system. The PET technique suffers from a limitation of both spatial and temporal resolution, which permits only accurate center of mass coordinates of activated regions. Functional mapping of the brain by nuclear magnetic resonance has been achieved with techniques depicting specific brain areas in action during a mental process. These techniques open up an entirely new domain for study and treatment of many problems linked to cognition including many in whom pain is a central feature. The many cerebral cortical areas involved in pain make it unlikely that any ablative procedure will achieve long sustained pain relief. The dual objective of relief of both pain and suffering is probably going to be attained only by activation of pain suppressor mechanisms. This may well require the added knowledge accessible only by functional magnetic resonance imaging.

Monoamines in the brain cerebrospinal fluid of facial pain patients.

The purpose of the study was to assay monoamines in cerebrospinal fluid (CSF) obtained from the trigeminal cistern of 64 patients with intractable facial pain. The CSF was analyzed for homovanillic acid (HVA), 5-hydroxyindoleacetic acid (5-HIAA), and 3-methoxy-4-hydroxyphenylglycol (MHPG), end-product markers of activity for the dopamine, serotonin, and norepinephrine systems, respectively. HVA averaged 121 ng/mL in these facial pain patients, compared to 150 to 550 ng/mL in 10 studies of ventricular brain CSF in assorted psychiatric and pain patients. 5-HIAA averaged 29 to ng/mL in our facial pain patients compared to 60 to 120 ng/mL in nine studies of ventricular brain CSF in assorted psychiatric and neurological patients. Trigeminal cistern CSF MHPG averaged 9 ng/mL, similar to the range of 13 studies of lumbar CSF of assorted psychiatric and pain diagnoses. These results indicate that (1) the electrochemical detection method provides a unique way of accurately measuring nanogram concentrations of multiple monoamines in a little as 0.25 mL of CSF; (2) trigeminal cistern and posterior fossa brain CSF monoamine metabolites reflect a different profile of dopaminergic and serotonergic functioning in these facial pain patients from that previously reported with lumbar CSF measurements of other patients; and (3) trigeminal sensory ganglion or brain dopamine and serotonin systems may be concomitantly dysfunctional in intractable facial pain.

Control of pain by direct electrical stimulation of peripheral nerves.

Our results after implanting electrodes around peripheral nerves in 69 patients over a 10 year period are only fair with but 17 individuals maintaining relief until death or until the present time. Thirteen others had weeks or months of temporary relief. A continuing use of transcutaneous and better still of percutaneous electrodes to guide the decision regarding implantation is almost certainly advisable. Intensive efforts in laboratory animal studies with models of chronic pain are needed to improve our understanding of exactly what we should be doing. Empirical sustained work with the individual patient is likely to improve the figures we have presented, even in our present state of ignorance.

Radical surgical treatment of craniopharyngioma.

There is evidence from this publication and those of Matson and colleagues that a determined effort at total excision of these tumors as the initial therapy is a tenable course of action. The main bases for this concept are: (1) that the dense gliosis characteristically intervening between these epithelial tumors and normal brain constitutes a margin of safety for the surgeon at least for the first several years such tumors are growing in the 3rd ventricle; (2) improved early diagnosis and better operative instruments, magnification, lighting, and technique are decreasing operative morbidity and mortality; and (3) new knowledge and new replacement therapy are reducing the burden of the metabolic and endocrine defects. Competing with this is the concept that rotationally delivered or even more precisely focused high energy photons and intracavitary beta-radiation have lower morbidity and mortality. The detailed and long term data on which to draw conclusions are not yet available. My medical colleagues and I are preparing case-by-case tables with all of the relevant facts to supply one component of the total picture.

Controlled thermocoagulation of trigeminal ganglion and rootlets for differential destruction of pain fibers: facial pain other than trigeminal neuralgia.

I describe the results of retrogasserian differential lidocaine block to aid in the selection of patients for a differential thermal lesion in the trigeminal ganglion and rootlets. This procedure temporarily duplicates the state of analgesia without anesthesia one seeks to make permanent with the radiofrequency heating. The results of this heating procedure are described in the treatment of 71 patients with facial pain of cancer, postherpetic, periodic migrainous neuralgia, acromegaly, trigeminal neuropathy, central pain, post-traumatic facial neuralgia, and atypical facial neuralgia.