Congenital insensitivity to noxious stimuli.

Cerebral-evoked potentials were used to study a 25-year-old man, the older of two siblings with congenital insensitivity to all noxious stimuli, gross impairment of temperature perception, and anhidrosis. Electrical stimulation of tooth pulp consistently eliciting pain and cerebral responses in normal subjects evoked neither cerebral potentials nor painful or other sensations in our patient. However, ordinarily painful electric shocks to the skin of his face evoked cerebral responses as well as sensations lacking disagreeable qualities. Those cerebral potentials elicited by electrical stimulation of the median nerve, clicks, and light flashes were within normal limits. These findings strongly suggest that a defect in transmission of noxious impulses presumably involving first order sensory neurons exists in our patient.

Acute failure of forebrain with sparing of brain-stem function. Electroencephalographic, multimodality evoked potential, and pathologic findings.

We describe a case of acute failure of forebrain with preservation of brain-stem function following cardiopulmonary arrest. This condition is distinguished from persistent vegetative or noncognitive states. Multimodality evoked potentials showed electroretinograms but no cerebral potentials to flash stimulation of both eyes; normal electrocochleograms and brain-stem auditory-evoked potentials to click stimulation of both ears; and Erb's point, N13, and P14 but no cortical responses to electrical excitation of both median nerves. Pathologic alterations consisted of pseudolaminar necrosis involving the whole cerebral cortex and other forebrain regions, with relative preservation of brain stem and spinal cord. Close correspondence existed between electrophysiologic, clinical, and major neuropathologic alterations.

EEG rhythm of alpha frequency in a 22-month-old child after strangulation.

A 22-month-old child suffered accidental strangulation, which rendered him comatose with intermittent generalized tonic-clonic seizures. His elecroencephalogram (EEG) displayed widespread activity of alpha frequency unreactive to sensory stimuli. Upon clinical recovery, a slower posterior EEG rhythm, attenuated by eye opening, was detected, which was more consistent with the patient's age. This observation is remarkable, because of the rarity of reports of an alpha pattern after cerebral anoxia in young children and the subsequent EEG and clinical evolutions.

Electrographic and clinical effects of intracarotid sodium amobarbital on bilateral myoclonic status epilepticus.

The effects of rapid intracarotid injection of 20 to 100 mg of sodium amobarbital were studied in three patients with bilateral myoclonic status epilepticus due to Jakob-Creutzfeldt disease, sequelae to anoxic encephalopathy, and hepatic coma, respectively. In each instance, the drug produced prompt abatement of clonic jerks contralaterally and attenuation of electroencephalographic epileptiform discharges ipsilaterally. These results suggest that the cerebral cortex actively participates in the elaboration of certain types of bilateral myoclonus in human beings.

Cerebral responses to electrical tooth pulp stimulation in man. An objective correlate of acute experimental pain.

The pulp of individual teeth of 17 normal adult volunteers was electrically stimulated via pairs of electrodes implanted into dentine. Computer-summated responses recorded from the surface of the head were composed of two concurrent sequences of events, one of which was seen maximally over midline areas and the other over the lower portions of the postcentral regions. Appropriate tests demonstrated that these wave forms represented cerebral tooth pulp-evoked potentials. Because tooth pulp-evoked potentials represent objective, quantifiable, nonverbal concomitants of central events associated with the perception of noxious stimuli, they may prove helpful in investigating acute experimental pain in man.

A case of persistent cortical deafness: clinical, neurophysiologic, and neuropathologic observations.

A 61-year-old man became deaf after the second of two cerebral infarctions which successively involved the temporal and adjacent cortices. He remained completely deaf until death 27 months later. Click stimulation demonstrated normal short-latency potentials, middle-latency responses better developed to stimulation of the right than of the left ear, and absent long-latency potentials. Neuropathologic examination showed cystic infarctions involving both transverse temporal gyri and adjacent cortical areas with preservation of the brainstem auditory nuclei. Persistent deafness can result from bilateral lesions involving the auditory and adjoining cortices.

Video game-related seizures: a report on 10 patients and a review of the literature.

OBJECTIVE: To further describe the features, postulated pathophysiology, treatment, and outcome of seizures occurring while playing or watching video games (video game-related seizures (VGRS)). DESIGN: We evaluated retrospectively 10 patients with VGRS seen by us and reviewed 25 reported cases. RESULTS: The 35 patients ranged in age from 1 to 36 years (mean: 13.2); and 26 subjects (74%) were male. Eight individuals (29%) had prior infrequent nonfebrile seizures, 4 (11%) had febrile convulsions, and 2 (6%) had a family history of epilepsy. VGRS consisted of generalized tonic-clonic seizures in 22 of 35 individuals (63%); absences in 2 (6%); simple partial seizures in 6 (19%); complex partial seizures in 4 (11%); and other manifestations in 4. Neurologic examination and computed tomographic and magnetic resonance imaging scans were normal. Electroencephalograms demonstrated generalized or focal, interictal or ictal epileptic patterns in 11 of 21 patients (52%) and photoparoxysmal responses in 17 of 32 (53%). Eleven of 15 individuals (73%) treated with video game (VG) abstinence alone, 3 of 6 who received anticonvulsants but played VGs, and 7 of 12 treated with combined VG abstinence and anticonvulsants had no further seizures. CONCLUSIONS: We postulate that a special convulsive susceptibility of selected neurons in striate, peristriate, infratemporal, and posterior parietal cortices to particular visual stimuli plays a major role in VGRS. VG abstinence is the treatment of choice of VGRS. Anticonvulsant medication is suggested only for those individuals who continue to play VGs or suffer from seizures triggered by other, unavoidable visual stimuli, or from unprovoked attacks.

Cone dysfunction in a subgroup of patients with autosomal dominant cerebellar ataxia.

Four patients with autosomal dominant cerebellar ataxia and retinal degeneration underwent neurologic and ophthalmologic examinations and computer-assessed corneal electroretinography. Previous reports described progressive panretinal degeneration initially involving the cones and subsequently spreading to the rods. By contrast, all our patients displayed evidence of selective dysfunction of the cone system in one or two successive electroretinograms, irrespective of their age or duration of visual symptoms. Color vision testing, funduscopy, and fluorescein angiography suggested a cone dystrophy. Within the period of observation only one patient showed progression of cone dysfunction. In patients with hereditary ataxias, quantitative electroretinography provides an objective and sometimes early indication of retinal degeneration and helps to characterize it.

Modified nomenclature for the "10%" electrode system.

A modified nomenclature for designating the auxiliary electrodes of the 10% system is described.

Discrepancy between intraoperative SSEP's and postoperative function. Case report.

The authors report a case in which midline myelotomy for the removal of a C4-T4 ependymoma was immediately followed by abolition of short-latency somatosensory evoked potentials (SSEP's) in response to bilateral posterior tibial nerve (PTN) stimulation which proved irreversible intraoperatively. Subsequent intraoperative testing also revealed obliteration of median nerve (MN)-elicited responses. Postoperatively, joint and vibration sensations deteriorated in the lower extremities and there was unchanged very mild impairment of light touch, pinprick, and temperature sensibilities without significant loss of muscle strength. Nearly 5 months after surgery, despite recovery of postural and vibratory senses in the lower limbs and of SSEP's in response to MN stimulation, no SSEP's could be demonstrated on PTN stimulation. The possibility of "false positive" results (that is, intraoperative SSEP abolition without postoperative motor deficits) and of dissociations between SSEP's and deep sensation should be taken into consideration when interpreting SSEP's intraoperatively.

Epileptic nystagmus.

Two cases of epileptic nystagmus (EN) are described. The first patient had no history of seizures and experienced attacks of EN associated with oscillopsia and followed by horizontal diplopia and esotropia. These episodes could be triggered by certain visual stimuli and ocular pressure. The second patient had a history of generalized tonic-clonic seizures. He displayed episodes of EN that changed direction in the course of the attacks simultaneously with a shift of the EEG discharge from one occipital region to the other. Cortical blindness followed postictally. On recovery from the postictal state, both patients were neurologically normal. With standard electrodes, the EEG seizures associated with EN involved the occipital, posterotemporal, and parietal areas of the scalp contralateral to the fast phase of the nystagmus. In the first patient, use of supplementary scalp electrodes further localized the seizures to an anterior occipital site intermediate between standard occipital and posterotemporal electrodes. Thirty-six previously reported cases of EN were associated with partial seizures. Horizontal EN most commonly results from seizure activity involving the occipital cortex, although participation of adjoining portions of the parietal and temporal cortexes is possible.

Cochlear summating potential recorded from the external auditory meatus of normal humans. Amplitude-intensity functions and relationships to auditory nerve compound action potential.

The summating potential (SP) and the auditory nerve compound action potential (AP) of the electrocochleogram were recorded from the external auditory meatus (EAM) of 10 normal subjects in response to alternating rarefaction and condensation clicks at 90-120 dB pe SPL. Both logarithmic and power functions suggested a similar strength of relationship between SP amplitude and stimulus intensity in each subject. However, a power function represented a more appropriate model of this relationship for the whole set of subjects than did the logarithmic function. Individual power function exponents varied from 0.35 to 0.56 with a weighted average of 0.46 and a S.E. of 0.03. By contrast, because of major heterogeneity of individual slopes at the high stimulus intensities eliciting EAM-measurable SPs, neither the logarithmic nor the power model provided a common description of the relationship between AP voltage and click strength for all subjects. Remarkable inter-individual variability also characterized the relationships between SP and AP amplitudes at various intensity levels and between the SP/AP amplitude ratio and click intensity. The lawful behavior of SP amplitude with varying click strength indicates that, in appropriate circumstance, non-invasive recordings from the ear canal of normal humans provide quantitative information on certain states of activity of cochlear receptors.

Long-term EEG-video-audio monitoring: computer detection of focal EEG seizure patterns.

Twelve individuals with medically refractory partial seizures had undergone EEG-video-audio (EVA) monitoring over 1-15 (mean 10.5) days. We selectively reexamined available 15-channel EEGs (video-cassettes) totaling 461 h and containing 253 EEG focal seizures. Computer analysis (CA) of these bipolar records was performed using a mimetic method of seizure detection at 6 successive computer settings. We determined the computer parameters at which this method correctly detected a reasonably large percentage of seizures (81.42%) while generating an acceptable rate of false positive results (5.38/h). These parameters were adopted as the default setting for identifying focal EEG seizure patterns in all subsequent long-term bipolar scalp and sphenoidal recordings. Factors hindering or facilitating automatic seizure identification are discussed. It is concluded that on-line computer detection of focal EEG seizure patterns by this method offers a satisfactory alternative to and represents a distinct improvement over the extremely time consuming and fatiguing off-line fast visual review (FVR). Combining CA with seizure signaling (SS) by the patients and other observers increased the correct detections to 85.38% CA is best used in conjunction with SS.

Heterozygote detection in X-linked recessive incomplete achromatopsia.

Carrier women in a family with X-linked incomplete achromatopsia (XLIA) were evaluated by means of ophthalmologic examinations, psychophysical tests, and electroretinography (ERG). Ophthalmologic examinations of five obligate carrier women and three women at 50% risk were normal except for the finding of high myopia in one carrier and one woman at risk. Detailed color vision testing was normal in all eight women. By contrast, the corneal full-field ERGs of three of five obligate carriers and two of three women at risk displayed major, qualitatively similar abnormalities of their cone components that were readily detected by our quantitative method. These b-wave alterations were similar in all five women regardless of refractive error. Our findings suggest that the ERG can identify some women who carry the gene for this X-linked recessive condition who are normal by clinical and psychophysical testing.

Long-term EEG-video-audio monitoring: detection of partial epileptic seizures and psychogenic episodes by 24-hour EEG record review.

Twenty-seven patients with medically refractory paroxysmal disorders underwent EEG-video-audio (EVA) monitoring in an inpatient neurology-neurosurgery unit over 1-15 (mean 8.9) days. Fast visual review of all EEG records (5,784 h) and subsequent analysis of synchronized EVA patterns demonstrated a total of 208 partial epileptic seizures (ES) in 12 individuals and 87 psychogenic episodes (PE) in 15 subjects. Clinical ES lasted 83.3 s on the average and were most frequent from day 7 to 9 of monitoring (42.3%) and during sleep (56.4%). PE were longer in duration (mean 724.5 s), most numerous during the first 2 days of monitoring (41.4%), and occurred exclusively during wakefulness. Subjects with PE signaled (by pressing on a push button) more events (35.6%) than did the individuals with ES (27.9%). Multiple observers raised the proportion of alarms to 69.0% of PE compared to 39.9% of ES. Following the alarm, nurses reached the patients' bedside within a brief time (mean 22.2 s). To differentiate partial ES from PE or to establish the association of these disorders, EVA monitoring is best performed around the clock over a period of 1-2 weeks. The limited number of paroxysmal events, especially ES, signaled by the patients should be considered when designing studies of the effectiveness of pharmacologic, surgical, and other treatments.

Cochlear summating potential to broadband clicks detected from the human external auditory meatus. A study of subjects with normal hearing for age.

The cochlear summating potential (SP) preceding the auditory nerve compound action potential (AP) was elicited by broadband alternating condensation and rarefaction clicks and recorded by noninvasive electrodes from the external auditory meatus (EAM) of 60 volunteers of both sexes, 12 to 67 years old, who had normal hearing for age. Quantitative data were obtained on: the number of ears displaying measurable SPs; the SP detection level; the SP onset, peak and rise times; the duration of the SP-AP complex; the SP amplitude; and the SP/AP amplitude ratio. Previously unknown relationships were unveiled between the amplitude, but not the temporal, measures of the SP and laterality, sex, age, and audiometrically determined hearing thresholds to 4 to 8 kHz tones. The highest correlations were obtained with these last thresholds, which suggested that receptors in the basal turn of the cochlea played a dominant role in the generation of the EAM-detected SP. To improve on existing techniques for determining abnormal SP elevation, a multiple regression method was devised that utilized sex, age, 4 to 8 kHz hearing thresholds, and AP voltage to establish upper normal limits of SP amplitude for individual subjects and ears.

Electrocorticography in patients with medically intractable temporal lobe seizures. II. Quantification of epileptiform discharges following successive stages of resective surgery.

We quantified retrospectively the interictal epileptiform discharges (EDs) detected visually in the electrocorticograms (ECoGs) of 42 patients undergoing successive stages of anterior temporal lobectomy for medically intractable temporal lobe seizures (TLS). Following first resection sparing the hippocampus (H) and the parahippocampal gyrus (PHG), EDs were recorded on both structures in all patients and by far exceeded in amount those on residual lateral infratemporal and lateral temporal cortices. Frequently, EDs occurred apparently simultaneously but with opposite polarities on the H and the PHG, but more complex relationships were also evident in most individuals. These features likely reflected abnormal post-synaptic activity generated at different locations and cortical depths within the H, PHG, or both. Quantification of epileptiform activity and the effects of selective anterior hippocampectomy or parahippocampectomy suggested that both the H and PHG had remarkable epileptogenic potential. Levels of epileptiform activity were not significantly different in the H and PHG and in the H of subjects with and without H sclerosis. After final resection, including the amygdaloid nucleus (AN), anterior H and PHG, interictal EDs were present, although markedly diminished, in 35 patients. Postresection foci were significantly less numerous and extensive, and attained smaller maximal voltages, than did foci before and after first resection.

Electrocorticography in patients with medically intractable temporal lobe seizures. I. Quantification of epileptiform discharges prior to resective surgery.

We studied retrospectively the intraoperative preresection electrocorticograms (ECoGs) of 72 patients undergoing surgery for medically intractable, mostly complex partial, temporal lobe seizures (TLS). Quantification of interictal epileptiform discharges (EDs) detected visually at each electrode location in 2 min recording epochs included computations of ED rates (EDs/min) and cumulative voltages (CuVs) (microV/min). Of 6388 EDs, 81% involved the infratemporal surface, 18% the lateral temporal surface and 1% the orbital frontal area. Forty-eight patients (67%) demonstrated multiple (up to 5 or more), temporally independent foci. Dominant foci in medial and lateral infratemporal locations were about equally common and were significantly more frequent than in lateral temporal locations. Rankings of ED CuVs and rates at individual cortical locations defined 4 areas of "relative interictal cortical epileptogenicity." These were arranged in an orderly pattern with the anterior parahippocampal gyrus and the inferomedial surface of the temporal tip displaying the highest and the lateral temporal and posterior infratemporal cortices showing the lowest propensity to the interictal epileptiform discharge. Individual areas were not characterized by distinct clinical seizure manifestations. Preresection ECoGs provide information on the epileptogenic dysfunction that involves most of the temporal lobe of patients with medically intractable TLS.