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Biomedical subjects

P C McCormick

Publications and source records attributed to P C McCormick.

35 records · Page 2Linked to original sources
PubMed1993

Monitoring of intraoperative motor-evoked potentials under conditions of controlled neuromuscular blockade.

Motor-evoked potentials were recorded after electrical spinal cord stimulation in 19 patients undergoing neurosurgical or orthopedic procedures. Anesthesia was maintained with nitrous oxide, opioids, and inhaled anesthetics. Vecuronium was infused sufficient to eliminate 90% of twitch tension. The spinal cord was stimulated using either epidural or subarachnoid electrodes. Compound muscle action potentials were recorded from quadriceps and tibialis anterior muscles. Well-formed, stable motor-evoked potentials were recorded in all but one patient, in whom a preexisting myelopathy was felt to preclude recording. Intraoperative deterioration of motor-evoked potentials occurred in one patient who had a postoperative neurologic deficit. This study demonstrates the feasibility and utility of intraoperative motor tract monitoring using direct spinal cord stimulation. Controlled neuromuscular blockade permits recording of compound muscle action potentials while eliminating patient motor activity that could interfere with surgery.

Action Potentials↗
PubMed1993

Pregnancy and discogenic disease of the spine.

Low back pain is common during pregnancy and is of moderate or severe intensity in about one fourth of all pregnancies. The etiology is multifactorial but in most cases is related to the physical and physiologic changes brought about by pregnancy. For most women, the pain resolves spontaneously, although they remain at higher risk for increased LBP in future pregnancies and for the development of symptomatic disc disease in later life. Many of the common treatments for LBP are contraindicated or must be modified in this setting. Neurologically symptomatic herniated discs are rare during pregnancy, yet, when indicated, pregnant women can safely undergo surgery.

Diagnosis, Differential↗
PubMed1992

The treatment of associated intracranial aneurysms and arteriovenous malformations.

Cerebral arterial aneurysm associated with arteriovenous malformation (AVM) has been described with a variable incidence, averaging 10% of AVM cases. The present series includes 39 patients with this association, derived from a total of 400 patients with AVM's evaluated and treated since 1970. The aneurysms are classified into four major groups, each carrying particular therapeutic implications. Optimum treatment of these lesions is based in part on a knowledge of the hemodynamic alterations associated with the AVM's. In most of these cases, the symptomatic lesion was treated first; occasionally, when feasible, both lesions were treated during the same operation. All patients had some form of treatment, either surgical or endovascular, directed to at least one of the two types of lesions. All symptomatic lesions were treated and all ruptured aneurysms were obliterated. There were no deaths in this series.

Adolescent↗
PubMed1992

Infections of the dural spaces.

Suppuration involving the epidural and subdural spaces is a rare occurrence in modern neurosurgical practice. Early diagnosis and appropriate treatment of infections of the dural spaces may avert the high incidence of neurologic disability and death traditionally associated with them, however. Prompt neurosurgical intervention in the treatment of these lesions has been the standard with which all other therapies have been compared.

Brain Abscess↗
PubMed1990

Intramedullary ependymoma of the spinal cord.

A consecutive series of 23 patients underwent operative removal of an intramedullary spinal cord ependymoma between January, 1976, and September, 1988. Thirteen women and 10 men between the age of 19 and 70 years experienced symptoms for a mean of 34 months preceding initial diagnosis. Eight patients had undergone treatment prior to tumor recurrence and referral. Mild neurological deficits were present in 22 patients on initial examination. The location of the tumors was predominantly cervical or cervicothoracic. Radiological evaluation revealed a wide spinal cord in all cases. Magnetic resonance (MR) imaging was the single most important radiological procedure. At operation, a complete removal was achieved in all patients. No patient received postoperative radiation therapy. Histological examination revealed a benign ependymoma in all cases. The follow-up period ranged from 6 to 159 months (mean 62 months) with seven patients followed for a minimum of 10 years after surgery. Fourteen patients underwent postoperative MR imaging at intervals ranging from 8 months to 10 years postoperatively. No patient has been lost to follow-up review and there were no deaths. No patient showed definite clinical or radiological evidence of tumor recurrence during the follow-up period. Recent neurological evaluation revealed functional improvement from initial preoperative clinical status in eight patients, no significant change in 12 patients, and deterioration in three patients. The data support the belief that long-term disease-free control of intramedullary spinal ependymomas with acceptable morbidity may be achieved utilizing microsurgical removal alone.

Adult↗
PubMed1990

Clinical evaluation of the spinal cord and nerve roots.

In this article the techniques of clinical neurological evaluation are discussed. It is suggested that correlation of the initial clinical evaluation with radiological investigation remains the most efficient method to determine the type, timing, and appropriateness of surgical intervention. An appreciation of the logical somatotopic organization of spinal cord tracts and cell groups forms the basis of precise localization and provides some insight into the etiology and prognosis of spinal cord dysfunction.

Humans↗
PubMed1990

Functional anatomy of the spinal cord and related structures.

This article reviews the anatomy of the vertebral canal and its contents from a surgical perspective. The normal and pathological relationships of intradural structures are addressed. Spinal cord blood supply, metabolism, and ischemia are discussed in detail. A clinically oriented biomechanical analysis of forces acting within the spinal canal under both physiological and pathological conditions is also presented.

Arteries↗
PubMed1990

Intradural extramedullary tumors in adults.

Meningioma, nerve sheath tumors, and filum terminale ependymoma account for over 90% of primary intradural extramedullary tumors in adults. The demographics, radiological evaluation, and surgical techniques employed for their removal are reviewed in this article. The authors' approach to intraspinal tumors with extraspinal extension is discussed.

Adult↗
PubMed1990

Intramedullary tumors in adults.

The authors review their approach to the surgical management of intramedullary neoplasms. An emphasis is placed on surgical technique and judgment based primarily on the gross characteristics of the tumor. Aggressive removal, irrespective of tumor histology, is recommended for those neoplasms that are clearly demarcated from surrounding spinal cord tissue.

Adult↗
PubMed1990

Miscellaneous intradural pathology.

The topics discussed in this article include secondary neoplasia, hemorrhage, meningeal cysts, infectious and inflammatory conditions, and intradural disc herniation. Although they are relatively uncommon in occurrence it is important that these disorders be included in the differential diagnosis of patients harboring intradural pathology. The epidemiology, clinical features, and treatment considerations of these conditions are presented.

Follow-Up Studies↗
PubMed1989

Metastatic carcinoma to the pituitary gland.

Four patients with metastatic carcinoma to the pituitary gland are presented. Two of these patients had no previous history of malignancy and, based on clinical, laboratory, and radiological evaluation, a preoperative diagnosis of pituitary adenoma was made. In one patient, the histological diagnosis of two consecutive tumour specimens, obtained 1 year apart, was pituitary adenoma. The correct diagnosis of metastatic renal-cell carcinoma was not ascertained until autopsy. In the second patient, a diffusely infiltrating breast carcinoma was diagnosed by mammography and confirmed by biopsy, after pathological examination of the sellar tumour revealed carcinoma. The third patient underwent mastectomy 3 years earlier for breast carcinoma and had known metastatic disease. The fourth patient had known metastatic endometrial carcinoma when she became symptomatic from a pituitary metastasis. The incidence, clinical features, and pathophysiology of metastatic carcinoma to the pituitary gland are discussed.

Adult↗
PubMed1989

Perioperative management of intracranial catastrophes.

The management and evaluation of neurosurgical intracranial catastrophes require a multidisciplinary approach to optimize outcome. Intracranial pathology must be rapidly evaluated. Clinically, the patient's mental status, the degree and extent of focal neurologic deficits, and the dynamic nature of any changes in clinical status are assessed. The CT scan is invaluable for diagnosing and monitoring the progress and extent of intracranial pathology. Medical therapy for the control of intracranial hypertension must be undertaken simultaneously. This begins with provision of an adequate, protected airway and support of cardiopulmonary function. Specific measures to control intracranial hypertension include hyperventilation, osmotherapy, CSF removal, seizure control, autonomic control, sedation (primarily thiopental), muscle relaxation, mild hypothermia, and, if indicated, steroids. The goal of intraoperative management is physiologic support of systemic and cerebral hemodynamics. There should be a smooth transition from the discovery of the patient in extremis through the period of medical stabilization, operative intervention, and ultimate delivery of the patient to the intensive care facility for extended treatment.

Anesthesia↗
PubMed1988

Metastatic carcinoma to pituitary adenoma. Report of two cases.

The authors present two patients with symptomatic carcinomas which have metastasized to pituitary adenomas. Despite the advanced age of these patients, the preoperative clinical and radiologic evaluations were consistent with pituitary adenoma. There was no previous history of malignancy in either patient, and the symptomatic pituitary metastases were responsible for the initial presentations. A review of the literature is presented with emphasis on the incidence and possible factors responsible for tumors metastasizing to distant neoplasms.

Adenoma↗
PubMed1988

Cavernous malformations of the spinal cord.

Six patients with intramedullary cavernous malformations of the spinal cord are presented. Four men and two women presented with acute, subacute, or episodic signs and symptoms of spinal cord dysfunction, ranging in duration from 3 days to 25 years. All patients underwent operative resection of the malformation. Complete removal was achieved in five patients. Neurological function either stabilized or improved postoperatively in all patients; follow-up ranged from 4 to 84 months. The increasing awareness of the propensity for recurrent hemorrhage, clinical features, and resectability of these malformations are discussed.

Adolescent↗
PubMed1988

Trigeminal schwannoma. Surgical series of 14 cases with review of the literature.

A consecutive series of 14 patients with trigeminal schwannoma managed surgically at the Neurological Institute of New York since 1970 is reported. Nine women and five men (mean age 40 years) were diagnosed following a mean symptom duration of 33 months. Abnormalities of trigeminal nerve function were present in 11 patients on admission examination. Facial pain was a prominent feature in eight patients. Two patients, both with schwannomas arising from the trigeminal root, presented initially with typical trigeminal neuralgia. Additional cranial nerve palsies or cerebellar or pyramidal tract signs were noted in eight patients. The surgical approach to these tumors depends on their anatomical location. Four patients had tumors confined to the middle fossa, three patients had tumors limited to the posterior fossa, and seven patients had both supratentorial and infratentorial components of their tumors. Twenty operative procedures were performed on these patients, resulting in complete extirpation in six patients, nearly complete removal in seven patients, and partial removal in one patient. Adherence of the tumor to the lateral wall of the cavernous sinus or the brain stem precluded total removal. There was one postoperative death. In the immediate postoperative period, abnormalities of cranial nerves controlling the extraocular muscles were common. In general, these deficits were transient; however, some permanent loss of trigeminal nerve function occurred in nine patients. Two patients required tarsorrhaphy for neurotropic keratitis, and two patients underwent cerebrospinal fluid (CSF) shunting procedures for hydrocephalus or for a persistent CSF leak. The follow-up period ranged from 4 to 177 months (mean 47 months). The clinical features, anatomical considerations, and surgical approach to these rare tumors are discussed. A clinical review of 106 additional cases of trigeminal schwannoma, reported in the English literature since 1935, is also presented.

Adolescent↗
PubMed1987

Differential diagnosis of pituitary tumors.

Many parasellar lesions may mimic pituitary adenomas clinically, endocrinologically, and radiologically. Certain patterns do lead suspicion toward the correct diagnosis, whereas in other cases the diagnosis may be difficult. For most of these lesions, the treatment of choice is different from that for a pituitary tumor, so correct diagnosis is of paramount importance. The presenting signs and symptoms as well as radiologic manifestations of parasellar tumors and conditions are discussed.

Abscess↗