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Biomedical subjects

J H Piatt

Publications and source records attributed to J H Piatt.

At least 19 recordsLinked to original sources
PubMed2000

A hazard of combining the infratentorial supracerebellar and the cerebellomedullary fissure approaches: cerebellar venous insufficiency.

The infratentorial supracerebellar approach is a popular technique for exposure of lesions of the superior vermis and pineal region. The cerebellomedullary fissure approach is enjoying increasing application as a technique for exposure of the fourth ventricle. Occasionally, a tumor that arises in the quadrigeminal plate or the superior vermis grows to fill the fourth ventricle, and for such a case a combination of the infratentorial supracerebellar approach and the cerebellomedullary fissure approach might be considered. We report a grave hazard of this combination. Two patients with tumors involving the superior vermis and filling the fourth ventricle were managed with a combined infratentorial supracerebellar/cerebellomedullary fissure approach. The first patient, who underwent a bilateral exposure, died on the sixth postoperative day due to massive hemorrhagic venous infarction of the cerebellum. The second patient, who was explored on one side only, suffered a protracted postoperative course characterized by suboccipital pain, torticollis, feeding difficulties and persisting hydrocephalus. Postoperative imaging showed swelling of the inferior vermis and ipsilateral hemisphere of the cerebellum with unilateral tonsillar herniation. Simultaneous compromise of the galenic and tentorial bridging veins and interruption of collateral pathways between these systems and the petrosal bridging veins, as in the combined infratentorial supracerebellar/cerebellomedullary fissure approach, may cause cerebellar venous insufficiency with venous congestion and possible venous infarction.

Adolescent↗
PubMed1999

The Chiari II malformation: lesions discovered within the fourth ventricle.

Structural lesions associated with the Chiari II malformation have been identified within the fourth ventricle in 8 patients. During the 42-month period encompassing the operations of the 7 patients treated surgically, only 9 other patients were explored without the discovery of some associated structural lesion. The patients ranged in age from 2 to 26 years. The following lesions were identified: glial or arachnoidal cysts (3 patients), glial or choroidal nodules (3 patients) and subependymoma (2 patients). These lesions were all situated in the roof of the fourth ventricle adjacent to or interspersed with the choroid plexus. Only the cystic lesions were identified by preoperative imaging. In only 1 case did the associated lesion, a 2-cm cyst, seem to contribute to the patient's clinical presentation. Structural lesions of the fourth ventricle associated with the Chiari II malformation are common in patients who are submitted to decompression. These lesions may be dysplasias of developmental origin, or they may be reactive lesions related to chronic compression and ischemia. They do not necessarily required biopsy or excision.

Adolescent↗
PubMed1999

Subdural empyema complicating cerebrospinal fluid shunt infection.

Subdural empyema has not been reported previously as a complication of cerebrospinal fluid (CSF) shunt surgery. An infant submitted to CSF shunt insertion for congenital hydrocephalus developed subdural empyema after a failed attempt to treat a superficial scalp wound infection with oral antibiotics. Enterobacter cloacae was isolated from the empyema. Temporizing management of the preceding superficial wound infection with oral antibiotics probably was the cause of this exotic pathogen. The treatment of infected scalp wounds contiguous with shunt hardware must be surgical.

Empyema, Subdural↗
PubMed1999

Some hypothalamic hamartomas contain transforming growth factor alpha, a puberty-inducing growth factor, but not luteinizing hormone-releasing hormone neurons.

Activation of LH-releasing hormone (LHRH) secretion, essential for the initiation of puberty, is brought about by the interaction of neurotransmitters and astroglia-derived substances. One of these substances, transforming growth factor alpha (TGFalpha), has been implicated as a facilitatory component of the glia-to-neuron signaling process controlling the onset of female puberty in rodents and nonhuman primates. Hypothalamic hamartomas (HH) are tumors frequently associated with precocious puberty in humans. The detection of LHRH-containing neurons in some hamartomas has led to the concept that hamartomas advance puberty because they contain an ectopic LHRH pulse generator. Examination of two HH associated with female sexual precocity revealed that neither tumor had LHRH neurons, but both contained astroglial cells expressing TGFalpha and its receptor. Thus, some HH may induce precocious puberty, not by secreting LHRH, but via the production of trophic factors--such as TGFalpha--able to activate the normal LHRH neuronal network in the patient's hypothalamus.

Astrocytes↗
PubMed1998

Chiari malformation associated with vitamin D-resistant rickets: case report.

INTRODUCTION: Craniocervical junction abnormalities have a wide range of origins, from rare congenital conditions to common arthritic processes. We present a rare case of foramen magnum stenosis with Chiari I malformation and associated syringomyelia, which resulted from vitamin D-resistant hypophosphatemic rickets. METHODS: This 12-year-old male patient had a history of vitamin D-resistant rickets, and he presented with a 1-year history of increasing upper extremity weakness and sharp pain in the left shoulder and arm. Magnetic resonance imaging of his spine showed a large syrinx from C2 to T7, with significant foramen magnum stenosis and a Chiari Type I malformation. RESULTS: The patient underwent craniocervical decompression, consisting of a suboccipital craniectomy and C1 laminectomy with duraplasty. A pathological evaluation of bone yielded no diagnostic abnormality. Postoperative magnetic resonance imaging showed significant reduction in the diameter of the cervical thoracic spinal cord syrinx 3 months after surgery. The patient's pain and sensation in his left arm had not improved by that time, and he still had some diffuse weakness in his arms. Two years later, he had persistent left shoulder girdle pain and his syrinx had collapsed, except for a small residual from T2 to T6. DISCUSSION AND CONCLUSION: The bone disease of vitamin D-resistant rickets can involve the base of the cranium, precipitating the development of the Chiari malformation and associated syringomyelia. We review the association between rickets and Chiari malformation and discuss the management of these patients.

Arnold-Chiari Malformation↗
PubMed1998

Spontaneous involution of a diencephalic astrocytoma.

We present the case of a child with a symptomatic diencephalic astrocytoma which involuted after needle biopsy without any adjuvant therapy. A tendency for certain childhood astrocytomas to regress after partial resection has been previously suggested. However, some authors have doubted whether or not such regression actually occurs. Our case radiographically documents the spontaneous involution of a low-grade astrocytoma.

Adult↗
PubMed1997

Developmental skills of children with spastic diplegia: functional and qualitative changes after selective dorsal rhizotomy.

OBJECTIVE: This study examined changes in muscle tone, passive range of motion, stability, and mobility in developmental skills at 6 months and 1 year after selective dorsal rhizotomy (SDR). DESIGN: Prospective outcome study of a consecutive sample. SETTING: Private children's hospital. PATIENTS: Twenty-six children with spastic diplegia: 13 independent and 13 dependent ambulators (assistive devices). RESULTS: A decrease in spasticity was seen at 6 months after SDR, with no further decrease at 1 year. Increases in passive range of motion of the hip and ankle were seen at 6 months after SDR. The ability to assume and maintain developmental positions with improved alignment and stability was seen more frequently at 6 months after SDR, whereas an improvement in the ability to perform transitional movements was seen more frequently at 1 year after SDR. CONCLUSION: SDR decreases spasticity and increases lower extremity range of motion in children with spastic diplegia and appears to be associated with the ability to assume a greater variety of developmental positions with improved alignment, thus greater stability. Improvements in the ability to perform difficult transitional movements at 1 year after SDR are most likely the result of the combined effect of maturation, SDR, and intensive therapeutic intervention.

Activities of Daily Living↗
PubMed1997

Shaving of the scalp may increase the rate of infection in CSF shunt surgery.

Hydrocephalic patients undergo repetitive surgical procedures, most of which involve the scalp. 141 shaveless operations involving scalp incisions for cerebrospinal fluid (CSF) shunts as well as 218 historical controls were reviewed after the senior author ceased shaving the scalp. The study population has been followed for a mean of 13.4 months and the control population for a mean of 38.6 months. The actuarial rate of infection at 1 year was 3.3% in the study population and 6.9% in the control population. Anesthesia times were not significantly different. Shaving of the scalp is not a critical step in the prevention of CSF shunt infection.

Cerebrospinal Fluid Shunts↗
PubMed1997

Resection of fourth ventricle tumors without splitting the vermis: the cerebellomedullary fissure approach.

OBJECTIVE: Standard surgical practice for excision of fourth ventricle tumors entails splitting the inferior vermis, but incision of the vermis and lateral retraction on the dentate nuclei and their outflow tracts have been implicated in the development of the so-called 'cerebellar mutism syndrome'. We describe a surgical approach in which the cerebellar vermis is preserved. METHODS: Clinical experiences with 11 patients harboring fourth ventricle tumors were supplemented by fixed and fresh cadaver dissections. Anatomic illustrations, prosections and intraoperative photographs are presented. The authors' case material is tabulated, and clinical examples are discussed. RESULTS: Dissection of the arachnoid membranes and division of filamentous arachnoidal attachments allow separation and elevation of the cerebellar tonsils and exposure of the tela choroidea along its attachment to the dorsal surface of the medulla at the taenia ventricularis. The tela can be opened by sharp microdissection from the foramen of Magendie to the foramen of Luschka to expose the lateral recess of the fourth ventricle. Division of the tela allows additional elevation of the cerebellar tonsils, which can be mobilized further by opening of the tonsillovermian fissures. Performance of this dissection bilaterally opens the entire inferior end of the fourth ventricle and, particularly after excision of a large fourth ventricle tumor, gives a panoramic view from one lateral recess to the other and from the obex to the aqueduct without incision of the vermis. CONCLUSION: The cerebellomedullary fissure approach yields exposure comparable to what can be achieved by splitting the vermis and may minimize the risk of neurological complications.

Adolescent↗
PubMed1996

Hydrocephalus and epilepsy: an actuarial analysis.

OBJECTIVE: To determine the prevalence of epilepsy among patients with hydrocephalus and to identify risk factors. METHODS: Retrospective chart review at a single institution was conducted. The definition of epilepsy used was long-term administration of antiepileptic drugs (AEDs) for suppression of seizures. Actuarial methodology was used, with initiation of AED therapy as the endpoint of the analysis. RESULTS: Insertion or revision of cerebrospinal fluid (CSF) shunts was performed on 464 patients at the study institution from 1976 through 1989. At the time of initial CSF shunt insertion, 12% of patients had already been treated with AEDs. After the 2nd year, the hazard rate for initiation of AED treatment was a constant 2% per year, and by 10 years after initial shunt insertion the estimated prevalence of AED treatment had risen to 33%. The cause of the hydrocephalus was a strong determinant of the prevalence of AED treatment, but most of the statistical effect of the cause was already manifest at the time of initial CSF shunt insertion. Age of patient at diagnosis of hydrocephalus, burr hole site, number of CSF shunt operations during follow-up, and history of shunt infection were factors that had no detectable association with AED treatment. CONCLUSION: Epilepsy is common among patients with hydrocephalus, and the risk of the development of epilepsy continues indefinitely for those patients. The complications of CSF shunt surgery seem to play a relatively minor role in the development of epilepsy in this patient population.

Actuarial Analysis↗
PubMed1996

Assessment of upper-extremity function in children with spastic diplegia before and after selective dorsal rhizotomy.

The upper-extremity function of 26 children (mean age 6.0 years) with spastic diplegia was assessed prior to and one year following selective dorsal rhizotomy (SDR). No significant change was found in upper extremity range of motion, muscle tone, or strength (MMT). A significant increase was noted in grasp strength bilaterally which could not be explained simply on the basis of maturation. Manipulation patterns were noted to improve significantly one year after SDR; however, this was proposed to be a maturation rather than intervention effect. Standardized test results revealed no significant improvement in functional hand use when the scores of children with spastic diplegia were compared with age-matched norms, to control for the effect of maturation. The significant improvement found in ability to toilet, dress and undress independently was most likely due to the effect of SDR on lower-extremity muscle tone. Further investigation with a matched control group would provide a conclusive result regarding the effect of SDR on upper extremity function and assist in understanding the maturation of hand function in children with spastic diplegia.

Activities of Daily Living↗
PubMed1996

Pumping the shunt revisited. A longitudinal study.

Most cerebrospinal fluid (CSF) shunts employed in the treatment of hydrocephalus include in their designs a pump mechanism that has been used in office practice as an indicator of whether the shunt is functioning properly; however, the pumping characteristics of shunts have been shown to correlate poorly with clinical status at a single point in time. A longitudinal study was performed to determine whether interval changes in the pumping characteristics of shunts correlate with changes in clinical status. 115 patients were examined on at least two occasions by a single pediatric neurosurgeon. At the time of the second examination, 10 patients were experiencing symptomatic shunt malfunction confirmed by neuroimaging investigations and operative findings; the remaining 105 patients were unchanged clinically at the time of the second examination. Considered as a test for CSF shunt malfunction, the interval shunt pumping test had a sensitivity of 0.50, a specificity of 0.64, and a likelihood ratio of 1.39. In the sample of patients studied, the negative predictive value was 0.93, and the positive predictive value was only 0.12. The interval shunt pumping test is not sensitive enough to rule out the possibility of shunt malfunction, nor can a positive interval shunt pumping test be considered an indication for an expensive diagnostic investigation in the asymptomatic patient.

Adolescent↗
PubMed1996

Tethered hindbrain. Case report.

The authors present the case of an 11-year-old boy with symptomatic tethering of the hindbrain related to a Chiari Type III malformation repaired at birth. Surgical release of the cord resulted in functional improvement.

Child↗
PubMed1995

Cerebrospinal fluid shunt failure: late is different from early.

Six hundred and seventy-one operations to insert or revise simple, linear cerebrospinal fluid shunts were performed in a single institution from 1976 through 1989. The results were analyzed using actuarial techniques. Failures within the first 8 months were defined as 'early', and subsequent failures were 'late'. Patient age did not quite attain significance as a determinant of the risk of late shunt failure (p = 0.054). The following factors had no effect on the risk of late failure: interval since last operation, etiology of hydrocephalus, identity of surgeon, burr hole site, type of valve, and whether the shunt was new or revised. Modes of shunt failure in the two phases were compared: there were proportionately more infections among early failures and proportionately more fractures/separations among late failures (chi-squared = 42.9, d.f. = 6, p < 0.000005). Shunts failing during the early phase were more often revised by removal and replacement of the entire system, whereas shunts failing later were more often revised by replacement of valve and/or abdominal catheter (chi-squared = 33.7, d.f. = 3, p < 0.000005). The late phase of shunt survival conformed very closely to an exponential decay model with a constant monthly risk of failure of 0.5% (r2 = 0.98). Contrary to intuition, cerebrospinal fluid shunts did not encounter increasing monthly risks of failure as they grew older. The contempt of familiarity has discouraged study of the mechanisms of shunt failure. Experience suggests that most early shunt failures are attributable to infection and other technical misadventures, but the mechanisms of late failure are distinct and incompletely understood.

Actuarial Analysis↗
PubMed1995

Agenesis and dysgenesis of the sacrum: neurosurgical implications.

We reviewed 27 patients with congenital anomalies of the sacral spine. There were 16 males and 11 females with a mean follow-up of 81.1 months (range 8-211 months). Fifteen patients had sacral agenesis and 12 had sacral dysgenesis. Fifteen patients had neuroimaging of the spine. Seven patients had conus termination below the L2 vertebral body. Four patients had associated thoracic syringomyelia and 6 patients were identified with caudal or dorsal lipoma. There were only two episodes of neurological deterioration, both in a single patient who had a lipomyelomeningocele, in 182 patient-years of follow-up. Four patients with low lying conus had pre-emptive spinal cord exploration for release of tethering in order to prevent neurological deterioration. Patients with agenesis or dysgenesis of the sacrum should undergo magnetic resonance (MR) imaging of the spine in order to detect spinal cord lesions associated with progressive neurological deterioration. Findings on MR imaging are more likely to correlate with clinical course than findings on skeletal radiography.

Abnormalities, Multiple↗