Thomas W. Farmer

Subdural empyema in infants, children and adults.

Subdural empyema is a fulminating, purulent, bacterial infection located between the dura and the pia arachnoidal membranes. It spreads over the convexity of one or both cerebral hemispheres, lies in the parafalcine region between the two cerebral hemispheres, or, rarely, is beneath the tentorium. Delay in its diagnosis and treatment may result in irreparable damage t o the central nervous system or in death. Kubik and Adams’ in 1943 and Courville’ in 1944 described in detail the symptoms, signs, and pathologic findings in this disorder. Subsequent workers3 3 4 have presented the results of treatment with surgical drainage combined with systemic and subdural antibiotic therapy. Bhandari and Sarkari’ in 1970 reported a series of patients treated with surgical drainage and systemic antibiotic therapy without subdural installations of antibiotics. All these series’ -’ primarily included children and adults, with only single cases reported in infants.

Treatment of intractable hiccups with valproic acid

we used valproic acid (VPA) to treat five patients with incapacitating, intractable hiccups. Symptoms were eliminated in four and markedly improved in one after other therapies (granulated sugar, carbamazepine, chlorpromazine, and nasopharyngeal stimulation) had failed. Effective peak VPA plasma levels ranged from 34 to 96 pg per milliliter.

Subdural empyema complicating meningitis in infants Improved prognosis

No deaths occurred among six consecutive cases of subdural empyema complicating meningitis in infants treated between 1968 and 1978 at North Carolina Memorial Hospital, Chapel Hill. Five of the six infants had no neurologic sequelae in follow-up periods ranging from 6 months to 7 years. This contrasts with a mortality rate of 50% in a previously reported series of infants with subdural empyemas treated between 1955 and 1966 at the same hospital. The reasons for improved prognosis include early diagnosis (computed tomography and subdural paracentesis) and adequate surgical drainage during intensive antibiotic therapy.

Refractory period of human muscle after the passage of a propagated action potential

Abstract The recovery of excitability after the passage of a propagated action potential was studied in fibres in human muscle stimulated directly by paired stimuli variable in strength and time interval. The evoked action potentials were all-or-none and originated from two or three muscle fibres. With increasing strength of the testing stimulus the refractory period decreased until the stimulus exceeded threshold by about 50 per cent. The relative and absolute refractory periods of different fibre bundles fell into two discrete groups. With a repetition rate of paired stimuli of 1 per sec. the absolute refractory periods of one group varied between 2.2 and 3.1 msec. and of the other group between 3.4 and 4.6 msec. (34–36.5°C). The absolute irresponsive periods showed no sign of this grouping; they exceeded the absolute refractory periods slightly. The absolute refractory and irresponsive periods increased with increasing repetition rate of paired stimuli. This indicates that the recovery time after paired responses considerably exceeds the recovery time after a single action potential. Both these recovery periods were prolonged by anoxia. The maximum frequency of trains of stimuli to which the fibre bundle could respond corresponded to the absolute refractory period determined by paired stimuli; but the number of identical responses to successive stimuli decreased with increasing stimulation frequency. Near the absolute refractory period the conduction velocity of the action potential evoked by the stimulus was identical with the velocity of the conditioning action potential. At intervals between the stimuli of 6–10 msec. the conduction velocity of the second action potential exceeded that of the conditioning action potential by 10–20 per cent. The threshold was lower to the testing than to the conditioning stimulus at stimulus intervals of 5 to 30 msec. As additional evidence of facilitation subthreshold stimuli could evoke responses after a number of applications.

Refractory and irresponsive periods of muscle in progressive muscular dystrophy and paresis due to lower motor neuron involvement.

The method has been described in detail previously. In brief, paired stimuli were delivered through a bipolar needle electrode inserted into the distal part of the muscle outside the end plate zone. Using different strengths of the testing stimulus, the refructory p e d was measured as the shortest time interval at which both the conditioning and the testing stimulus evoked action potentials. The time interval between these 2 action potentials, denoted as the irresponsive period, was measured as well. The action potentials were recorded by means of a concentric needle electrode inserted 15 to 25 mm. proximal to the stimulating electrode. The strength of the conditioning stimulus and the position of the stimulating and recording electrodes were adjusted until an all-or-none response of short duration (1.5 to 6 msec ) was obtained, indicating activation of 2 to 3 fibers.2 The strength of the conditioning stimulus was usually 1.2 to 1.3 times threshold. The strength of the testing stimulus was increased stepwise from threshold to 2 or 3 times threshold. The absolute refractory and irresponsive periods were found when the strength of the testing stimulus was such that the time interval between effective stimuli and between the corresponding action potentials was shortest. In all experiments, the intramuscular temperature, measured by 2 thermocouples inserted to lie close to the stimulating and recording electrode tips, was maintained at normal values by means of a heating pad placed under the muscle. This was of particular importance in paretic muscles, which frequently had a temperature below normal.

Bacterial cerebral vasculitis.

THE SUDDEN ONSET of focal cerebral dysfunction during bacterial parameningeal and leptomeningeal infection is often due to cerebral vasculitis.1-8 It is usually clinically impossible to distinguish between cerebral thrombophlebitis and cerebral arteritis or to distinguish between the resultant cerebral infarction and cerebritis. This is therapeutically unimportant because effective treatment of these disorders includes appropriate administration of antibacterial drugs and a careful search for conditions which require surgical drainage. This is a report of 10 patients with cerebral vasculitis associated with pyogenic infections of the paranasal sinuses, the middle ear, or the skull. Cases of cavernous sinus thrombophlebitis, overt subdural empyema, and brain abscess are not included. Since none of these patients had the cerebrospinal fluid findings of acute, generalized pyogenic leptomeningitis, the bacterial etiology was not initially suspected in 2 patients. Paranasal sinus radiographs were valuable in establishing the site of the initial infection, even when skull radiographs did not reveal any evidence of sinus involvement. The radioisotope brain scan was useful in localization of the cerebral abnormality. Cerebral thrombophlebitis and arteritis were sometimes detected in these patients with cerebral angiograPhY.

The “hypernormal” CT scan in dementia Bilateral isodense subdural hematomas

Enlarged ventricles and prominent sulci are common findings on computed tomography (CT) in elderly demented patients. Three such patients were found to have small, symmetric ventricles and minimal sulci on tomography; these CT scans were considered “hypernormal” for the patients ages and clinical syndromes. Bilateral isodense subdural hematomas were subsequently diagnosed by isotope brain scans in two cases and by angiography in the third. A “hypernormal” CT scan in an elderly demented patient suggests the possibility of bilateral isodense subdural hematomas, and requires further evaluation with isotope brain scan and, if necessary, angiography.

Neuroimaging of a New Familial Disorder; Ataxia, Chorea, Seizures, and Dementia

The neuroimaging findings observed in a family with a previously reported syndrome of progressive ataxia, chorea, seizures, and dementia include an unusual combination: (1) bilateral basal ganglia calcification limited to the globus pallidus on brain computed tomography; (2) abnormal focal and diffuse areas of increased signal intensity in the cerebral white matter on brain magnetic resonance imaging; and (3) mild to moderate degrees of atrophy of the cerebrum, cerebellum, and brainstem. These neuroimaging findings define further this new clinical entity.

Cineradiographic diagnosis of neurological diseases

THE APPLICATION of image amplification fluorography and cineradiography has proved to be a very satisfactory method of radiological diagnosis of diseases of the spinal cord and subarachnoid cisterns.lj2 Current improvements over the original methods of study are largely the result of the introduction of standard serial filming techniques, similar to those employed in examination of the gastrointestinal tract, and the introduction of improved contrast materials. In the past several years, we have performed 182 myelograms and 106 pneumoencephalograms using cinefluorography and cineradiography. We use a fluoroscopic tilt table with a 22-cm. image-amplifier adaptation unit with high-gain image tube and orthicon television with two monitors. A deluxe 16-mm. cine camera is used for filming. The monitor picture is quite good during cine filming.

Oseillopsia in association with cerebellopontine angle cholesteatoma

OSCILLOPSIA is a visual experience in which the patient sees a stationary object moving regularly to and fro in a horizontal, less commonly in a vertical, or rarely in an oblique plane. Horizontal oscillopsia is associated with horizontal nystagmus on direct forward gaze, or fixation nystagmus, whereas vertical oscillopsia is experienced with vertical nystagmus on direct forward gaze. Oscillopsia and fixation nystagmus may be present constantly or recur paroxysmally. The term, oscillopsia, was first used by Rricknerl in 1936 to describe these apparent oscillations of objects in the visual field. The clinical findings in a patient with recurrent paroxysms of oscillopsia associated with a cerebellopontine angle cholesteatoma are presented. During attacks of horizontal oscillopsia, paroxysms of horizontal nystagmus on direct forward gaze were observed.