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Biomedical subjects

T H Milhorat

Publications and source records attributed to T H Milhorat.

At least 19 recordsLinked to original sources
PubMed2001

Otologic manifestations of Chiari I malformation.

OBJECTIVE: To assess the prevalence of otologic symptoms in patients undergoing surgical decompression for symptomatic Chiari I malformation. STUDY DESIGN: Cross-sectional, prospective, nonrandomized. SETTING: Urban tertiary referral center. PATIENTS: Patients with Chiari I malformation before surgical intervention. INTERVENTIONS: None. MAIN OUTCOME MEASURE: Results of completed questionnaire. RESULTS: Sixteen consecutive patients with Chiari I malformation completed the self-administered questionnaire. Eighty-one percent of patients reported episodic aural fullness, 81% reported tinnitus, 69% reported vertigo, and 56% reported fluctuating hearing loss. Headaches were reported as frequently as aural fullness and tinnitus. CONCLUSIONS: Most patients with Chiari I malformation have symptoms that mimic primary otologic pathologic changes. The existence of common pathophysiologic mechanisms is proposed.

Adult↗
PubMed2000

Classification of syringomyelia.

Syringomyelia poses special challenges for the clinician because of its complex symptomatology, uncertain pathogenesis, and multiple options of treatment. The purpose of this study was to classify intramedullary cavities according to their most salient pathological and clinical features. Pathological findings obtained in 175 individuals with tubular cavitations of the spinal cord were correlated with clinical and magnetic resonance (MR) imaging findings in a database of 927 patients. A classification system was developed in which the morbid anatomy, cause, and pathogenesis of these lesions are emphasized. The use of a disease-based classification of syringomyelia facilitates diagnosis and the interpretation of MR imaging findings and provides a guide to treatment.

Adolescent↗
PubMed2000

Pain and syringomyelia: a review.

The pathophysiological basis of chronic pain syndromes remains poorly defined. Central and dysesthetic pain are probably the most disabling of sensory disturbances associated with syringomyelia, and, unfortunately, effective treatment remains elusive. In this paper, the authors review their institutional experience with both clinical and laboratory studies of patients with syringomyelia, and they review the relevant literature. To date, there is no consensus as to the best treatment for central cord pain syndromes, although there are many promising areas of current research involving the use of neurochemicals in the spinal cord.

Animals↗
PubMed2000

A genetic hypothesis for Chiari I malformation with or without syringomyelia.

In several reports the authors have suggested occasional familial aggregation of syringomyelia and/or Chiari 1 malformation (CM1). Familial aggregation is one characteristic of traits that have an underlying genetic basis. The authors provide evidence for familial aggregation of CM1 and syringomyelia (CM1/S) in a large series of families, establishing that there may be a genetic component to CM1/S in at least a subset of families. The authors observed no cases of isolated familial syringomyelia in their family studies, suggesting that familial syringomyelia is more accurately classified as familial CM1 with associated syringomyelia. These data, together with the cosegregation of the trait with known genetic syndromes, support the authors' hypothesis of a genetic basis for some CM1/S cases.

Arnold-Chiari Malformation↗
PubMed1999

Chiari I malformation redefined: clinical and radiographic findings for 364 symptomatic patients.

OBJECTIVE: Chiari malformations are regarded as a pathological continuum of hindbrain maldevelopments characterized by downward herniation of the cerebellar tonsils. The Chiari I malformation (CMI) is defined as tonsillar herniation of at least 3 to 5 mm below the foramen magnum. Increased detection of CMI has emphasized the need for more information regarding the clinical features of the disorder. METHODS: We examined a prospective cohort of 364 symptomatic patients. All patients underwent magnetic resonance imaging of the head and spine, and some were evaluated using CINE-magnetic resonance imaging and other neurodiagnostic tests. For 50 patients and 50 age- and gender-matched control subjects, the volume of the posterior cranial fossa was calculated by the Cavalieri method. The families of 21 patients participated in a study of familial aggregation. RESULTS: There were 275 female and 89 male patients. The age of onset was 24.9+/-15.8 years (mean +/- standard deviation), and 89 patients (24%) cited trauma as the precipitating event. Common associated problems included syringomyelia (65%), scoliosis (42%), and basilar invagination (12%). Forty-three patients (12%) reported positive family histories of CMI or syringomyelia. Pedigrees for 21 families showed patterns consistent with autosomal dominant or recessive inheritance. The clinical syndrome of CMI was found to consist of the following: 1) headaches, 2) pseudotumor-like episodes, 3) a Meniere's disease-like syndrome, 4) lower cranial nerve signs, and 5) spinal cord disturbances in the absence of syringomyelia. The most consistent magnetic resonance imaging findings were obliteration of the retrocerebellar cerebrospinal fluid spaces (364 patients), tonsillar herniation of at least 5 mm (332 patients), and varying degrees of cranial base dysplasia. Volumetric calculations for the posterior cranial fossa revealed a significant reduction of total volume (mean, 13.4 ml) and a 40% reduction of cerebrospinal fluid volume (mean, 10.8 ml), with normal brain volume. CONCLUSION: These data support accumulating evidence that CMI is a disorder of the para-axial mesoderm that is characterized by underdevelopment of the posterior cranial fossa and overcrowding of the normally developed hindbrain. Tonsillar herniation of less than 5 mm does not exclude the diagnosis. Clinical manifestations of CMI seem to be related to cerebrospinal fluid disturbances (which are responsible for headaches, pseudotumor-like episodes, endolymphatic hydrops, syringomyelia, and hydrocephalus) and direct compression of nervous tissue. The demonstration of familial aggregation suggests a genetic component of transmission.

Adolescent↗
PubMed1998

Continuous intracranial multimodality monitoring comparing local cerebral blood flow, cerebral perfusion pressure, and microvascular resistance.

Maintaining cerebral perfusion pressure (CPP) above 70 mmHg is currently a mainstay of neurosurgical critical care. Shalmon, et al. recently showed poor correlation between CPP and regional cerebral blood flow (CBF) [1]. To study the relationship between CPP and CBF, at a microvascular level, we retrospectively analyzed multimodality digital data from 12 neurosurgical critical care patients in whom a combined intracranial pressure (ICP)--laser Doppler flowmetry (LDF) probe (Camino, San Diego) had been placed. Over the entire interval of continuous monitoring for all patients, 97% of local CBF data was at ischemic levels below a CPP of 70 mmHg. For CPP above 70 mmHg, local CBF data had considerable dispersion ranging from ischemic (71%), to normal (19%), and hyperemic (10%) levels. Elevated jugular bulb oxyhemoglobin saturation levels (SjO2) complemented intervals of hyperemia. Autoregulation was impaired or absent in all monitored patients. We conclude that with disrupted autoregulation, CPP above 70 mmHg does not necessarily insure adequate levels of cerebral perfusion. Restoration and maintenance of adequate cerebral perfusion should be performed under the guidance of direct CBF monitoring.

Adolescent↗
PubMed1998

Treatment of rhinocerebral mucormycosis with intravenous interstitial, and cerebrospinal fluid administration of amphotericin B: case report.

IMPORTANCE: Rhinocerebral mucormycosis is extremely difficult to treat. Approximately 70% of patients are poorly controlled diabetics, and many of the remainder are immunocompromised as a consequence of cytotoxic drugs, burn injuries, or end-stage renal disease. Despite standard treatment consisting of surgical debridement and the intravenous administration of amphotericin B, rhinocerebral mucormycosis is usually a fatal disease. CLINICAL PRESENTATION: We describe the case of a 16-year-old male patient with juvenile onset diabetes mellitus who presented with fever, right-sided hemiparesis, and dysarthria. Axial view computed tomography revealed abscess formation in the left basal ganglia and frontal lobe, which was proven by stereotactic biopsy to contain Rhizopus oryzae. INTERVENTION: Intravenous administration of amphotericin B (30-280 mg/dose) was begun on the day of admission. On hospital Day 20, after the occurrence of frank abscess formation, the lesion was aggressively debrided. Despite these therapies, there was neurological deterioration characterized by the development of hemiplegia and aphasia. Sequential computed tomographic scans enhanced with contrast medium demonstrated progressively enlarging lesions. Ommaya reservoirs were placed into the abscess cavity and the frontal horn of the contralateral lateral ventricle. The patient was then treated with intracavitary/interstitial injections of amphotericin B during the course of 80 days and three doses of intraventricular amphotericin B. Clinical and radiographic improvement was achieved after treatment. Two years after the initial diagnosis, magnetic resonance imaging of the brain showed no evidence of disease and an examination revealed a neurologically intact and fully functional patient. CONCLUSION: We conclude that with an infection as morbid as rhinocerebral mucormycosis, it is advisable to use surgical debridement and all available routes for delivering amphotericin B to infected cerebral parenchyma, which include intravenous, intracavitary/interstitial, and cerebrospinal fluid perfusion pathways.

Adolescent↗
PubMed1997

Intramedullary pressure in syringomyelia: clinical and pathophysiological correlates of syrinx distension.

OBJECTIVE: The pathophysiological effects of syrinx distension are incompletely understood. Although it is generally assumed that the accumulation of fluid within syrinx cavities can contribute to neurological dysfunction, there are no reports describing intramedullary pressure in syringomyelia. The purpose of the current study was to measure syrinx pressures in patients with progressive clinical deterioration and to correlate these data with neurological deficits and intraoperative physiological findings. METHODS: Intramedullary fluid pressure was measured manometrically in 32 patients undergoing syrinx shunting procedures. The data were correlated with syrinx morphology, intraoperative somatosensory evoked potentials, laser Doppler measurements of local spinal cord blood flow (six patients), and neurological findings before and after syrinx decompression. RESULTS: Syrinx pressures recorded under atmospheric conditions ranged from 0.5 to 22.0 cm H2O (mean = 7.7 cm). There was a significant elevation of the cardiac pulse (mean = 0.7 cm H2O) and the respiratory pulse (mean = 1.1 cm H2O) that was consistent with raised cerebrospinal fluid pressure. Syrinx pressures decreased to subatmospheric levels after surgical drainage. In 18 of 24 patients with predrainage somatosensory evoked potential abnormalities, syrinx decompression produced a consistent reduction of N20 latencies (mean change = 0.49 ms +/- 0.094 SE right, P = 0.002; 0.61 ms +/- 0.089 SE left, P = 0.001) and a similar but less consistent increase in N20 amplitudes (mean change = 0.17 mV +/- 0.103 SE right, P = 0.115; 0.31 mV +/- 0.097 SE left, P = 0.027). Measurements of local spinal cord blood flow revealed very low baseline values (mean = 12.2 arbitrary units +/- 13.9 standard deviation), which increased to intermediate levels (mean = 144.7 arbitrary units +/- 42.6 standard deviation) after syrinx decompression. Patients with syrinx pressures greater than 7.7 cm H2O tended to have more rapidly progressive symptoms, exhibited greater improvements after shunting, and had a higher incidence of postoperative dysesthetic pain. CONCLUSION: The current study is the first to measure intramedullary pressure in a human disease. Evidence is presented that distended syringes are associated with varying levels of raised intramedullary pressure that can accentuate or induce neurological dysfunction by the compression of long tracts, neurons, and the microcirculation. Symptoms referrable to raised intramedullary pressure are potentially reversible by syrinx decompression.

Adolescent↗
PubMed1996

Dysesthetic pain in patients with syringomyelia.

Dysesthethic pain is a common complaint of patients with syringomyelia, traumatic paraplegia, and various myelopathic conditions. Because cavitary lesions of the spinal cord can be defined with good resolution by magnetic resonance imaging, syringomyelia provides a potential model for examining anatomic correlates of central pain. In this study, a syndrome of segmental dysesthesias, characterized by burning pain, hyperesthesia, and a variable incidence of trophic changes, was described by 51 of 137 patients (37%) with syringomyelia at the time of clinical presentation. Complete magnetic resonance scans, including axial images, demonstrated extension of the syrinx into the dorsolateral quadrant of the spinal cord on the same side and at the level of pain in 43 of 51 patients (84%). Surgical treatment of syringomyelia resulted in the relief or improvement of dysesthetic pain in 22 of 37 patients (59%), but 15 patients (41%) reported no improvement or an intensification of pain despite collapse of the syrinx. Postoperative dysesthetic pain was often a disabling complaint that responded poorly to medical therapy, including analgesics, sedatives, antiepileptics, antispasmodics, and anti-inflammatory agents. In most cases, there was a gradual improvement of symptoms, although six patients continued to complain of pain 24 to 74 months postoperatively. Prompt but transient relief was achieved in two of two patients with regional sympathetic blocks, and prolonged relief was achieved in one patient by stellate ganglionectomy. We conclude that painful dysesthesias can be caused by a disturbance of pain-modulating centers in the dorsolateral quadrant of the spinal cord and have certain causalgia-like features that respond in an unpredictable way to surgical collapse of the syrinx.

Adolescent↗
PubMed1996

Continuous postoperative lCBF monitoring in aneurysmal SAH patients using a combined ICP-laser Doppler fiberoptic probe.

Cerebral vasospasm remains the principal cause of morbidity and mortality following successful clipping of intracranial aneurysms. Current management often requires subjective judgments concerning presumed abnormalities of cerebral blood flow. In this study, a combined intracranial pressure (ICP)-laser Doppler flowmetry (LDF) fiberoptic probe that permits continuous monitoring of local cerebral blood flow (lCBF) was used in the postoperative management of 20 aneurysm patients. Using this probe, lCBF was simultaneously recorded and integrated on a real time basis with other physiological parameters, including ICP, systemic arterial pressure, pulmonary arterial pressure, central venous pressure, and pulse oximetry. The combined probe also provided the ability to obtain precise and detailed information concerning the presence or absence of cerebral autoregulation and CO2 vascular reactivity, and allowed calculation of the cerebral vascular resistance. Continuous monitoring of lCBF in this manner complemented by transcranial Doppler and angiographic data permitted early detection of cerebral ischemia, helped to differentiate cerebral ischemia from edema and hyperemia, was useful in titrating blood pressure and fluid management, provided direct feedback about the effectiveness of instituted therapies, and determined early on when medical management was of no avail and that interventional neuroradiology was indicated. Evidence is presented that the presence of angiographic vasospasm and increased velocities on TCD do not always correlate with ischemia in the microcirculation and that direct measurements of lCBF are often at variance with calculations of cerebral perfusion pressure (CPP).

Adult↗
PubMed1996

Intraoperative improvement of somatosensory evoked potentials and local spinal cord blood flow in patients with syringomyelia.

This report is the first to correlate data concerning intraoperative somatosensory evoked potentials (SSEPs) and local spinal cord blood flow (ISCBF) in patients with syringomyelia. In a consecutive study, bilateral median nerve SSEPs were recorded intraoperatively in 13 patients undergoing a syrinx shunt to the posterior fossa cisterns (syringocisternostomy). ISCBF was measured in five of these patients using laser doppler flowmetry (LDF) calibrated in arbitrary units (AU). SSEP recordings obtained 30 min after syrinx decompression demonstrated a slight but consistent reduction of N20 latencies (mean change: 0.53 ms right, p < 0.003; 0.58 ms left, p < 0.001) concurrent with a similar but less consistent increase of N20 amplitudes (0.16 mV right, p = 0.256; 0.29 mV left, p = 0.03). Prior to shunting, LDF recordings from the spinal cord overlying syrinxes revealed very low ISCBF values in five of five patients (mean LDF, 13.2 AU +/- 15.3 SD). Immediately after shunting, there was a dramatic rise of ISCBF (mean LDF, 241.2 AU +/- 106.3 SD) associated with visualized hyperemia of the spinal cord and pial vessels. The ISCBF fell to intermediate levels after 2 min (157.2 AU +/- 33.0 SD) and remained at these levels during the interval of recording (5 min). Hyperventilation testing in two patients prior to shunting revealed no change in ISCBF consistent with a loss of CO2 vascular reactivity and a paradoxical increase of ISCBF in one patient 5 min after shunting. Each patient in this study experienced neurological improvement in the immediate postoperative period associated with collapse or disappearance of the syrinx on magnetic resonance imaging scans. Because syrinx shunting results in an acute decompression of the distended spinal cord, it is possible that the rapid improvement of SSEPs reflects a relief of mechanical factors such as stretching and compression of nervous tissue. However, the LDF findings in this study suggest that distended spinal cord cavities are also capable of producing regional ischemia. A significant reduction of ISCBF is a possible contributing cause of neurological injury and SSEP abnormalities. Intraoperative improvement of SSEPs and ISCBF were found to correlate well with neurological recovery following syringocisternostomy. Our results indicate that SSEP monitoring can provide useful information during surgical procedures for syringomyelia and that further experience with LDF monitoring may provide insights into the pathophysiology of this condition.

Adolescent↗
PubMed1996

Distribution of substance P in the spinal cord of patients with syringomyelia.

The distribution of substance P, a putative neurotransmitter and pain-related peptide, was studied using the peroxidase-antiperoxidase immunohistochemical method in the spinal cords obtained from autopsy of 10 patients with syringo-myelia and 10 age- and sex-matched, neurologically normal individuals. Substance P immunoreactivity was present in axons and in terminal-like processes in close apposition to neurons in the first, second, and third laminae of the dorsal horn. Smaller amounts of peroxidase-positive staining were found in the fifth lamina of the dorsal horn, the intermediolateral nucleus, the intermediomedial nucleus, and the ventral horn. In nine of 10 patients with syringomyelia, there was a substantial increase in substance P immunoreactivity in the first, second, third, and fifth laminae below the level of the lesion. A marked reduction or absence of staining was present in segments of the spinal cord occupied by the syrinx. Central cavities produced bilateral abnormalities, whereas eccentric cavities produced changes that were ipsilateral to the lesion. No alterations in staining were found in the spinal cord of an asymptomatic patient with a small central syrinx. The authors conclude that syringomyelia can be associated with abnormalities in spinal cord levels of substance P, which may affect the modulation and perception of pain.

Adult↗
PubMed1995

Computerized tomography (CT) localized stereotactic craniotomy for excision of a bacterial intracranial aneurysm.

BACKGROUND: The treatment of bacterial intracranial aneurysms include long-term antibiotic therapy and surgical clipping or resection. Direct surgical approaches to these aneurysms are often complicated by their peripheral location. METHODS: We report the use of a computerized tomography (CT) localized stereotactic craniotomy for the excision of a ruptured peripheral bacterial intracranial aneurysm. RESULTS: The Leksell Steiner-Lindquist microsurgical guide, with its fiberoptic helium-neon laser, allowed for rapid isolation of the distal aneurysm with minimal cerebral dissection. Since the inflammatory lesion was well demonstrated on postcontrast CT scan, this modality, rather than angiography, was used for localization. CONCLUSIONS: In the future, stereotactic craniotomy may facilitate aggressive surgical therapy for infectious aneurysms previously thought not suitable for direct operative approach.

Adult↗
PubMed1995

Clinicopathological correlations in syringomyelia using axial magnetic resonance imaging.

Axial magnetic resonance (MR) images of non-neoplastic spinal cord cavities were reviewed in 115 patients with otherwise complete neurological and neuroradiological findings. The variations in axial morphology revealed three distinct cavitary patterns. These patterns were as follows: 1) symmetrically enlarged central cavities (28 patients); 2) central cavities that expanded paracentrally in one or more focal areas (36 patients); and 3) eccentric cavities that were off-center, frequently irregular, and sometimes associated with myelomalacia (51 patients). The radiological patterns of spinal cord cavitation correlated well with recently reported histopathological findings that distinguish simple dilations of the central canal, dilations of the central canal that dissect paracentrally, and primary cavitations of the spinal cord parenchyma (extracanalicular syringes). Like histologically confirmed central canal syringes, MR-defined central cavities were associated with pathogenic factors that affect the dynamics of the cerebrospinal fluid, including hindbrain malformations, hydrocephalus, and extramedullary obstructive lesions. Eccentric cavities resembled extracanalicular syringes and occurred typically with disorders that damage spinal cord tissue (e.g., trauma, infarction, meningitis/arachnoiditis, spondylosis/disc herniation, radiation necrosis, and transverse myelitis). Analysis of clinical findings at the time of MR imaging established the following correlations. 1) Symmetrically enlarged central cavities were asymptomatic or produced nonspecific neurological signs. 2) Central cavities that expanded paracentrally were associated with segmental signs referable to the paracentral component. 3) Eccentric cavities produced various combinations of long tract and segmental signs that could usually be related to the level, side, and specific quadrant of spinal cord cavitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1995

Resolution of chronic cluster headache after resection of a tentorial meningioma: case report.

Cluster headache is almost always idiopathic, but, in rare cases, associated intracranial lesions have been found. We describe a patient who had chronic cluster headache for more than 20 years. The headache immediately resolved upon resection of a tentorial meningioma. Prior reports of cluster headache as a manifestation of structural disease are briefly reviewed. In the patient described, the pain was referred from the right tentorium cerebelli to the right side of the face, in accordance with reported studies on the subjective localization of pain referred from posterior fossa structures. The accompanying abnormalities of autonomic function may have been mediated by central autonomic reflexes that are also involved in the pathogenesis of idiopathic cluster headache.

Autonomic Nervous System Diseases↗