Adjunctive hyperbaric oxygen in the treatment of thermal burns. An economic analysis.

Current reimbursement for burn care underscores the importance of cost containment in the treatment of burn injuries. We evaluate the economic impact of adjunctive hyperbaric oxygen in burns of 19% to 50% total body surface area in patients admitted to our burn center from January 1982 to July 1987. Length of hospitalization, number of surgical procedures, and total cost of care, exclusive of surgical fees, were examined. Eleven patients did not receive adjunctive hyperbaric oxygen therapy, whereas 10 did. The hyperbaric oxygen-treated group had an average decrease in length of stay of 14.8 days, a reduction of surgical procedures of 39%, and an average saving per case of $31,600.

Adjunctive hyperbaric oxygen therapy reduces length of hospitalization in thermal burns.

The use of adjunctive hyperbaric oxygen therapy as part of a comprehensive program of burn care at our institution has resulted in a statistically significant reduction in length of hospital stay (p = less than 0.012) with no increase in cost of hospital care in patients suffering burns over 18% to 39% of total body surface area.

Postictal serum creatine kinase in the diagnosis of seizure disorders.

We prospectively correlated daily serum creatine kinase (CK) levels with the occurrence of different types of epileptic and nonepileptic seizures documented by video EEG recording in 22 hospitalized patients. Prolonged postictal CK elevations, 8.0 to 19.2 times baseline, were seen following six (15%) of 41 generalized tonoclonic seizures. No CK elevations were seen following 147 complex partial, focal motor, absence, and tonic seizures or 55 psychogenic seizures, 89% of which involved vigorous muscular activity. Six of 12 patients with generalized tonoclonic seizures had postictal CK elevations compared with none of six patients with psychogenic seizures and none of 15 patients with complex partial, focal motor, absence, and tonic seizures. Thus, postictal CK determination can serve as an adjunctive test for differentiation between psychogenic and epileptic generalized tonoclonic seizures.

Hypothermia and barbiturate coma for refractory status epilepticus.

Three pediatric patients with generalized status epilepticus unresponsive to therapy with conventional anticonvulsants were successfully treated with moderate hypothermia (30 degrees to 31 degrees C) and barbiturate coma with thiopental. All 3 patients were treated with thiopental at doses producing burst suppression or an isoelectric tracing on the EEG and thiopental and barbiturate levels were followed sequentially in the plasma. Continuous thiopental infusion rates of 5 to 55 mg/kg X h maintained burst suppression and correlated with plasma thiopental levels of 25 to 40 mg/dl. Total doses of thiopental used to obtain and maintain burst suppression ranged from 15 to 50 g over 48 to 120 h. In all 3 patients, control of the status epilepticus was obtained. Moderate hypothermia and thiopental barbiturate coma are indicated in patients with generalized tonic-clonic status epilepticus which cannot be controlled with standard anticonvulsant drug therapy. This regimen has the advantage that the patient can be managed in an ICU without the need for general anesthesia with volatile anesthetic agents.

Recording of auditory evoked potentials in man using chronic subdural electrodes.

With the aid of chronic subdural electrodes we have been able to record from the posterior banks of the sylvian fissure, auditory evoked potentials (AEPs) that had morphologies and peak latencies compatible with the primary AEPs described by Celesia and Puletti (1969). These AEPs had amplitudes that were not only affected by the side of stimulus presentation but were maximal in an area close to the primary auditory cortex. The AEPs also displayed an extremely steep spatial gradient and were not altered by pentobarbitone sodium and nitrous oxide anaesthesia. Together, these properties suggest that these subdurally recorded potentials are near-field evoked potentials from the primary auditory cortex. The focal nature of these potentials also allows them to be used as effective electrophysiological tools for localization of the primary auditory cortex in patients.

The location of speech and writing functions in the frontal language area. Results of extraoperative cortical stimulation.

In three patients stimulation of the frontal speech area resulted in one or more of the following symptoms: speech arrest, writing arrest, or impaired rapid alternating movements of the tongue, fingers or toes. Speech arrest could be altered at individual points either with or without impairment of rapid movements or writing, but writing was not impaired without concomitant difficulties with either speech or rapid finger movements. Our data suggest that the frontal speech area may function to integrate complex motor functions, some speech related and others not. We also confirm previous conclusions that Exner's writing centre is not separate from Broca's area and that the writing defect in Broca's aphasia can occur without involvement of the motor strip.

Cortical somatosensory evoked potentials in response to hand stimulation.

Somatosensory evoked potentials were recorded from chronically implanted subdural electrodes in six patients with intractable seizures. The following conclusions were reached: 1) The initial cortical negativity-positivity (N1 with a latency of about 20 msec and P2 with a latency of about 24 msec) recorded in the postcentral area was an expression of the classical primary surface positivity, but N1 was generated by the posterior pole of an early horizontal dipole in area 3b, and P2 was generated by the positive pole of a slightly delayed vertical dipole in area 1 and 2.2) P2 permitted the most accurate localization of the primary somatosensory area. 3) No potentials were elicited in the primary somatosensory area by stimulation of the ipsilateral hand. 4) No cortical potentials were seen at stimulation intensities below the sensory threshold. The cortical distribution of evoked potentials evoked by weak and strong intensities had significantly different distribution. 5) The recovery function of cortical evoked potentials showed a U-curve with an early period of facilitation (10 to 30 msec) followed by a prolonged period of subnormality which peaked at about 50 msec. The recovery curve at different cortical loci differed.

Sensory seizure mimicking a psychogenic seizure.

A patient had episodes of bilateral paresthesias with retained consciousness. The attacks were clinically considered to be psychogenic seizures. Electroencephalography indicated that the attacks were epileptic, perhaps originating from the second sensory area. Electroencephalographic recording of a seizure is essential in differentiating epileptic from psychogenic episodes.

Brain stem auditory evoked potentials in posterior circulation surgery.

The objectives of this study were to evaluate the use of brain stem auditory evoked potentials (BAEPs) in 10 adult patients with vascular disorders of the posterior circulation that were treated surgically and to compare the BAEPs with the neurological findings. The vascular lesions included basilar artery stenosis in 3 patients, vertebral artery stenosis in 1 patient, brain stem/cerebellar arteriovenous malformation in 2 patients, and basilar artery aneurysm in 4 patients. Measurement of BAEPs were carried out during operation in all cases. Eight patients had BAEPs measured before operation, and 9 patients had BAEPs measured after operation. Repeat postoperative studies were performed in patients with changes in neurological status. In general, BAEP abnormalities correlated with the neurological findings before and after operation. Six patients had normal intraoperative studies. None of them had clinical findings of pontomesencephalic dysfunction after operation. Three patients with significant BAEP abnormalities during operation had neurological findings of pontomedullary ischemia after operation. Transient BAEP changes in 1 patient were thought to be the result of brain stem retraction. The BAEPs were lost in 3 patients who died. The use of BAEP measurement did not lengthen the operative procedures. However, the technique used in this study required 4 to 8 minutes for the accumulation and interpretation of each average, thereby delaying feedback to the surgeon. The results of this study suggest a potential role for BAEP monitoring in identifying brain stem injury during posterior circulation surgery.

Origin of far-field subcortical evoked potentials to posterior tibial and median nerve stimulation. A comparative study.

Posterior tibial nerve (PTN) evoked potentials (EPs) at the lumbar-low thoracic level have waveforms similar to median nerve (MN) EPs at the cervical level. They consist of a short-duration negativity (N18 and N10, respectively), which reflects the afferent volley before it enters the spinal canal, and a longer-duration, later negativity (N20 and N12, respectively), which consists mainly of slow frequencies and most probably is a postsynaptic dorsal cord potential. At the neck-scalp derivation the MN EP consists of two near-field negativities (N10 and N12) that are recorded from the neck electrode and two far-field positivities (P11 and P13) that are recorded from the scalp electrode. The neck-scalp response to PTN stimulation consists of a near field potential N24 that is followed by a far-field potential P27.

Benign focal epileptiform discharges in childhood migraine (BFEDC).

Interictal EEGs were studied in 100 children, ages 3 to 15 years. Records were interpreted independent of history; 89% were normal, 9% had benign focal epileptiform discharges (BFEDC), one had temporal spikes, and one had background slowing. The nine patients with BFEDC did not differ from the others. None had epilepsy. This incidence of 9% is higher (p less than 0.0001) than the incidence of BFEDC in the normal population (1.9%). The significance of this finding is not clear, but migraine and benign focal epilepsy of childhood may be genetically linked, or the vascular abnormality of migraine may cause brain injury to produce sharp waves of low epileptogenicity. These results do not suggest that headaches are epileptic.

Surgical monitoring of spinal cord function: cauda equina stimulation technique.

Spinal cord and subcortical brain stem evoked potentials had an amplitude at least 2 times higher when the cauda equina rather than bilateral peripheral nerves was stimulated. Cauda equina stimulation is indicated when potentials to peripheral nerve stimulation are absent or are too low in amplitude to permit reliable surgical monitoring. The technique is essentially without risks, but should be performed with a small lumbar puncture needle (21 to 22 gauge), and is contraindicated in patients with general infections, increased cerebrospinal fluid pressure, or a hemorrhagic tendency (thrombocytopenia or anticoagulant therapy).

Submersion accidents in children with epilepsy.

The risks of submersion accidents, both drowning and near-drowning, for children with seizure disorders were calculated from the present study of six children with epilepsy in a total group of 100 children with postsubmersion syndrome and from five other reported studies. Analysis of data shows that the risk for patients with seizure disorders is four times that of the normal population. Persons with epilepsy should never swim without a lifeguard or competent swimmer being aware of the diagnosis and keeping close surveillance while they are swimming. Hyperventilation, a normal occurrence while swimming, may predispose patients with epilepsy to seizures and submersion accidents by increasing the propensity to seizures. In this study, three of the victims had at least one anticonvulsant drug level within the therapeutic range immediately after the submersion accident. Therapeutic drug levels are no guarantee that seizures will not occur during swimming.

Paradoxical lateralization of parasagittal sharp waves in a patient with epilepsia partialis continua.

We present a patient with epilepsia partialis continua involving the right leg who demonstrated sharp waves paradoxically distributed over the vertex and right hemisphere. Posterior tibial nerve evoked potentials also showed a similar paradoxical lateralization. We postulate that generators situated on the mesial surface of the left hemisphere projected their activity obliquely, leading to paradoxical lateralization of the recorded electrical activity.

A new technique for intraoperative monitoring of spinal cord function: multichannel recording of spinal cord and subcortical evoked potentials.

A new technique for intraoperative monitoring of spinal cord function is described. Evoked potentials to peripheral nerve stimulation are recorded with interspinous ligament needles from below and from two or more levels above the surgery. Simultaneously subcortical potentials are recorded with scalp electrodes from cervical-scalp derivations. Simultaneous recordings from multiple levels (below and above the surgical procedure) permit reliable differentiation between technical problems and alteration of cord function due to the surgical procedure. The interspinous ligament technique for recording of spinal potentials has significant advantages over previous monitoring techniques. One case in which monitoring during surgery detected a reversible acute spinal cord dysfunction is described.

Chronic cortical electrode array for seizure investigation.

Localization of seizure focus if surgical extirpation is contemplated is critical. It is routine to use cortical recording and stimulation for this purpose but the limited time available in the operating room limits what can be learned. We report a flexible electrode array of four 0.05 disc which can be banked to larger sizes, and left in place subdurally as well as epidurally. It can be used for stimulation as well as recording.

Early somatosensory potentials evoked by median nerve stimulation: intraoperative monitoring.

We identified the sites of origin of the somatosensory evoked potentials to median nerve stimulation by recording directly from the cervical cord in the course of intraoperative monitoring. The N9 potential occurred before any potentials recorded from the cord or dorsal roots. Potentials with latencies corresponding to N11 were recorded at the median nerve root entry zone of the lower cervical cord. High-amplitude potentials were recorded at the level of the foramen magnum, with latencies approximating or following P13, suggesting that this potential is generated at the cervicomedullary junction.