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Biomedical subjects

L M Hamed

Publications and source records attributed to L M Hamed.

At least 19 recordsLinked to original sources
PubMed1999

Tonic ocular tilt reaction simulating a superior oblique palsy: diagnostic confusion with the 3-step test.

BACKGROUND: The tonic ocular tilt reaction (OTR) consists of vertical divergence of the eyes (skew deviation), bilateral conjugate ocular torsion, and paradoxical head tilt. The head and superior pole of both eyes are rotated toward the hypotropic eye. OBJECTIVE: To describe ocular motility and torsion findings in 5 patients with OTRs that mimicked superior oblique palsies (SOPs). RESULTS: In 5 patients, results of the 3-step test suggested an SOP (bilateral in 1 patient); however, no patient had the expected excyclotorsion of the hypertropic eye. Two patients had conjugate ocular torsion (intorsion of the hypertropic eye and extorsion of the hypotropic eye), and 2 patients had only intorsion of the hypertropic eye. All had other neurologic features consistent with more widespread brainstem disease. CONCLUSIONS: Vertical ocular deviations that 3-step to an SOP are not always caused by fourth nerve weakness. When a patient with an apparent fourth nerve palsy has ocular torsion that is inconsistent with an SOP, OTR should be suspected, especially if vestibular system or posterior fossa dysfunction coexists. The rules for the 3-step test for an SOP may be fulfilled by damaging the otolithic projections corresponding to projections of the contralateral anterior semicircular canal. Because results of the Bielschowsky head tilt test may be positive in patients with the OTR, the feature distinguishing OTR from an SOP is the direction of torsion. We advocate use of a fourth step-evaluation of ocular torsion-in addition to the standard 3 steps.

Adult↗
PubMed1999

Treatment of acute comitant esotropia in Chiari I malformation.

PURPOSE: To explore the appropriate treatment of acute comitant esotropia in patients with Chiari I malformation. DESIGN: Interventional case reports and literature review. PARTICIPANTS: Two patients with Chiari I malformation presenting with acute comitant esotropia are described. INTERVENTION: Strabismus surgery, then neurosurgical decompression of the Chiari I malformation was performed. MAIN OUTCOME MEASURE: Both patients were evaluated for resolution of esotropia and other ocular motility problems. RESULTS: After initially successful strabismus surgery, both patients developed recurrent esotropia with diplopia, which resolved on suboccipital decompression. CONCLUSION: Comitant esotropia may recur and other eye movement disorders may develop after initially successful strabismus surgery in patients with Chiari I malformation. The data suggest that the appropriate sequence of treatment should first be suboccipital decompression, then strabismus surgery if spontaneous realignment does not occur, but further studies are needed to confirm this impression.

Acute Disease↗
PubMed1998

High prevalence of bihemispheric structural and functional defects in Sturge-Weber syndrome.

Abnormal cerebral venous drainage is associated with hypoxia and glucose deprivation, which can account for progressive neurologic deterioration in Sturge-Weber syndrome. Although developmental delay is common in Sturge-Weber syndrome, bihemispheric calcification is uncommon. Computed tomography (CT) and magnetic resonance imaging (MRI) were used to study the neuroanatomy, while single photon emission computed tomography (SPECT) was used concurrently to evaluate perfusion and glucose metabolism using 99mTc hexamethylpropyleneamine oxime (HMPAO) and [18F] fluorodeoxyglucose (FDG), respectively. Ten patients (10 to 22 years of age) with previously diagnosed Sturge-Weber syndrome, port-wine nevi, and clinical evidence of seizures or stroke-like episodes were studied. Five children with onset of seizures in the first year of life had overall clinical severity comparable to that of children with later-onset seizures. Calcification was present in both hemispheres in one patient; six additional patients had other radiologic evidence of bihemispheric disease; SPECT studies detected bihemispheric disease in four cases. Our study is the first to concurrently evaluate structure, perfusion, and glucose metabolism in Sturge-Weber syndrome and to show a mismatch between functional and structural brain imaging in both cerebral hemispheres. Widespread abnormalities of cerebral perfusion and glucose metabolism might explain the high prevalence of developmental delay associated with Sturge-Weber syndrome. Longitudinal studies are needed to define better the natural history of neurologic deterioration and radiologic progression that relates to central nervous system circulatory dysfunction in Sturge-Weber syndrome.

Adolescent↗
PubMed1998

Central nervous system structure and function in Sturge-Weber syndrome: evidence of neurologic and radiologic progression.

Sturge-Weber syndrome is characterized by the presence of a port-wine nevus, epilepsy, stroke-like episodes, headache, and developmental delay. We studied 20 cases to test the hypothesis that decreased cerebral blood flow alters neurologic function by affecting cellular glucose metabolism. Group A consisted of 10 patients with a mean age of 1.75 years and early seizure onset (6.8 months), whereas group B was composed of older patients (mean age, 15.3 years) with later onset of seizures (3.7 years). Neurologic disease was more severe in group A, but group B had more widespread structural brain defects - shown on computed tomographic scans and magnetic resonance imaging - and metabolic brain defects shown on hexamethylpropyleneamine oxime and [18F] fluorodeoxyglucose single photon emission computed tomographic scans. Six group A cases had hypoperfusion at baseline and five of nine had worsening of perfusion and glucose metabolism 1 year later. A total of 119 stroke-like episodes occurred in six group A cases and eight group B cases; there were 65% fewer strokes in children treated with aspirin. The data suggest that progressive hypoperfusion and glucose hypometabolism are associated with neurologic deterioration in Sturge-Weber syndrome. Longitudinal studies are needed to better define the natural history of disease and to evaluate the safety and efficacy of aspirin therapy.

Adolescent↗
PubMed1997

"Joubert syndrome" revisited: key ocular motor signs with magnetic resonance imaging correlation.

Joubert syndrome is characterized by episodic hyperpnea and apnea, developmental delay, hypotonia, truncal ataxia, ophthalmologic abnormalities, and vermian dysgenesis. We studied 15 patients with the diagnosis of Joubert syndrome to (1) more fully define the syndrome's clinical features, and (2) correlate the clinical features with magnetic resonance imaging (MRI) findings. Eight of 15 patients had a history of episodic hyperpnea and apnea. All patients had developmental delay and hypotonia. Of the 13 patients receiving detailed neuro-ophthalmologic evaluations, three had optic nerve dysplasia, pendular nystagmus, and gaze-holding nystagmus. All 13 patients had a normal vestibulo-ocular reflex based on head thrust, but had absent to poor ability to cancel the vestibulo-ocular reflex horizontally and vertically. Twelve of 13 patients had impaired smooth pursuit. Twelve of 13 patients had defects in initiation of saccades and quick phases. Two of the most consistent radiologic features were absent or hypoplastic posterior cerebellar vermis, and deformed midbrain and pontomesencephalic junction, which based on ocular motor physiology correlate with the vestibulo-ocular reflex cancellation/ pursuit defect and saccade initiation defect, respectively. As a result of midbrain, vermian, and superior cerebellar peduncle abnormalities, axial neuroimaging showed a unique "molar tooth" appearance of these structures. These results indicate that Joubert syndrome results from maldevelopment of the midbrain and cerebellar vermis, producing a pathognomonic sign on MRI.

Adolescent↗
PubMed1996

Venous stasis orbitopathy: a clinical and echographic study.

AIMS: A variety of acute and chronic orbitopathies may be distinguished by standardised echography. Venous stasis orbitopathy (VSO) often presents with orbital signs when secondary to cavernous sinus and middle cranial fossa disorders. In this study, the aim was to assess whether differentiation between vascular and nonvascular causes of VSO could be made on the basis of clinical and echographic features at the time of presentation. METHODS: This study comprised 37 patients with echographic features of VSO (17 patients with arteriovenous fistulae, confirmed by computed tomography imaging or angiography, and 20 patients with non-vascular diseases). Excluded were patients with orbital mass lesions detected by echography and muscle enlargement due to other causes (for example, orbital myositis). Patients with a suspected mass involving the orbital apex and echographic features of VSO were included. After full neuro-ophthalmic and ocular examination, both orbits were examined to document maximal thickness and reflectivity of four recti muscles and compared with the normal contralateral orbit with standardised A-scan (Kretz-technik 7200MA or Ophthascan) and contact B-scan (Ultrascan or Ophthascan S). RESULTS: Cumulative ocular recti muscle thickness was significantly greater in patients with arteriovenous fistulae compared with the non-fistula group (23.3 (SD 3.7) and 17.8 (2) mm, p = 0.001). Clinically, the presence of a bruit and a uniocular rise in intraocular pressure were significantly greater in the fistula group of patients. CONCLUSIONS: Standardised echography is a safe and non-invasive method of diagnosing VSO in patients presenting with signs of proptosis, ophthalmoplegia, and inflammation of the conjunctiva. Furthermore, using these standard techniques the two major causes of VSO (arteriovenous fistulae and compressive mass lesions) could be differentiated.

Aged↗
PubMed1996

Neovascular glaucoma after carotid endarterectomy.

The authors examined a patient who had neovascular glaucoma (NVG) shortly after ipsilateral carotid endarterectomy and followed the patient's clinical course. The authors speculate that the sudden reperfusion after endarterectomy that occurs in patients with combined central retinal artery occlusion and carotid occlusive disease may enhance the circulation of preformed angiogenesis factors, leading to the development of neovascularization. The authors recommend frequent and careful surveillance of patients with central retinal artery occlusion associated with carotid occlusive disease if ipsilateral carotid endarterectomy is performed.

Aged↗
PubMed1994

Fixation duress in the pathogenesis of upper eyelid retraction in thyroid orbitopathy. A prospective study.

BACKGROUND: Upper eyelid retraction in thyroid eye disease may be caused by proptosis, levator and Müller's muscle infiltration with fibrosis or individual fiber enlargement, excessive sympathetic innervation, abnormal adhesions between levator palpebrae muscle and surrounding tissues, or fixation duress. Fixation duress refers to upper eyelid retraction while fixating with an eye with inferior rectus muscle restriction due to excessive simultaneous firing of the ipsilateral superior rectus and levator palpebrae muscles. METHODS: The authors prospectively examined six patients with strabismus and thyroid eye disease associated with inferior rectus restriction and upper eyelid retraction in whom the eyelid retraction was suspected clinically to be a result of fixation duress. All six patients underwent recession of both inferior recti ranging from 3 to 6.5 mm (mean, 4.5 mm) to improve the ocular motility and alignment, reduce the diplopia, and mitigate the upper eyelid retraction. RESULTS: Reduction of upper eyelid retraction measured as the preoperative versus postoperative difference in corneal light reflex-upper eyelid margin measurements was achieved in all patients postoperatively, ranging from 1.5 to 5.5 mm (mean, 3.2 mm). Only one patient showed significant residual retraction to warrant consideration of upper eyelid surgery. CONCLUSION: Fixation duress plays a significant role in upper eyelid retraction of thyroid eye disease in a subset of patients with restriction of the inferior rectus muscle. In this selected group of patients, the upper eyelid retraction may be reduced or eliminated upon proper recession of the tight inferior rectus muscle(s).

Diplopia↗
PubMed1994

Value of thallium-201 SPECT imaging in childhood brain tumors.

Thallium-201 chloride single photon emission computed tomography (201Tl SPECT) has been proposed as a diagnostic tool in the assessment of patients with brain tumors. We performed SPECT scans coupled with magnetic resonance imaging (MRI) in children with brain tumors to determine the sensitivity and potential value of SPECT in neuro-oncology. Each patient was injected with 2.5-3.0 mCi of thallium chloride, followed by technetium-99m HMPAO (5-15 mCi) to assess cerebral perfusion. 201Tl uptake was imaged with triple-headed SPECT in 20/24 (83%) histologically and anatomically diverse neoplasms with MRI-measurable residual disease, including 13/16 (80%) posterior fossa tumors. 201Tl SPECT demonstrated uptake in tumors with MRI volumes ranging from 0.03 to 60 cm3. 201Tl SPECT imaging was not correlated with the following MRI features: gadolinium enhancement, necrosis, exophytic, unicentric and multicentric. 201Tl uptake was not detectable in patients with tumors of maldevelopmental origin or radionecrosis. It is suggested that 201Tl SPECT is an important imaging adjunct in the assessment of children with brain tumors.

Adolescent↗
PubMed1994

Temporary blindness in the TUR syndrome.

The TUR syndrome is a clinical disorder consisting of circulatory, gastrointestinal, and neurologic signs that are infrequently seen in some patients undergoing endoscopic surgery of the prostate gland with the use of nonconductive irrigating fluids. Several theories of its pathogenesis have been proposed. The condition may occasionally be associated with bilateral profound loss of vision. We report a patient with the TUR syndrome who suffered bilateral temporary blindness and speculate on the etiology of the visual loss and localization of the dysfunction along the visual pathway.

Ammonia↗
PubMed1993

The prevalence of neurologic dysfunction in children with strabismus who have superior oblique overaction.

BACKGROUND: Children with certain neurologic diseases (hydrocephalus, meningomyelocele, or cerebral palsy) have been reported to manifest a high frequency of A-pattern strabismus and superior oblique overaction. However, it is not generally recognized whether children with strabismus who have superior oblique overaction are more likely to have concurrent neurologic diseases than those without superior oblique overaction. In this study, the authors examine this issue. METHODS: The authors retrospectively reviewed the medical records of all patients (n = 168) with overdepression of the downturned eye in adduction, who were examined between October 1989 and March 1992. A randomly selected population of children with strabismus who did not have overdepression of the eye on infraduction and adduction served as controls (n = 98). Patients with simulating or confounding conditions such as pseudo-superior oblique overaction, inferior rectus skew deviation (alternating skew on lateral gaze), and restrictive or paralytic strabismus, and who were older than 20 years of age, were excluded. RESULTS: One hundred twelve patients with true superior oblique overaction were analyzed. Of these 112 patients, 45 (40.2%) had concurrent neurologic abnormalities, compared with less than one fifth (17.3%) of control subjects (17 of 98) (P < or = 0.001). CONCLUSIONS: Children with strabismus who have superior oblique overaction were found to have higher prevalence of concurrent neurologic diseases than control subjects. Superior oblique overaction may represent a clinical marker for an associated neurologic dysfunction, possibly representing a form of skew deviation in some cases.

Adolescent↗
PubMed1993

Alternating skew on lateral gaze. Neuroanatomic pathway and relationship to superior oblique overaction.

BACKGROUND: Previous studies of patients with heterogeneous, often diffuse neurologic disorders concluded that the neurologic substrate for alternating skew on lateral gaze may be localized at the level of the brain stem tegmentum or the cervico-medullary junction, or both. The localized nature of brain tumors offers an opportunity to further investigate the anatomic localization for this as well as other conditions. METHODS: To test the hypothesis that cervico-medullary and cerebellar lesions are responsible for alternating skew on lateral gaze, the authors investigated a series of 50 children with brain tumors, 39 of whom showed neuro-ophthalmologic abnormalities on clinical testing. Seven children had alternating skew on lateral gaze. RESULTS: All seven children with alternating skew on lateral gaze showed neoplastic involvement at the level of the cervico-medullary junction and/or the cerebellum on critical analysis of neuro-imaging studies. CONCLUSION: The authors conclude that the neuroanatomic substrate for alternating skew on lateral gaze is localized at the level of the cervico-medullary junction and/or the cerebellum. Knowing that (1) alternating skew on lateral gaze closely mimics superior oblique overaction clinically, (2) superior oblique overaction is frequently found in patients with myelomeningocele, and (3) myelomeningocele is uniformly associated with Arnold-Chiari type II which includes cerebellar and cervico-medullary region abnormalities, the authors propose that alternating skew on lateral gaze and superior oblique overaction associated with myelomeningocele have similar neuroanatomic pathways.

Adolescent↗
PubMed1993

Brainstem glioma: I. Pathology, clinical features, and therapy.

Gliomas that arise in the brain stem have been associated with a poor prognosis. Diagnostic neuroimaging readily identifies the tumor as it extends between normal brainstem structures. Histologic sampling of tumor with stereotactic methods is notoriously unreliable in establishing a definitive prognosis. Clinical trials that incorporate high-dose chemotherapy, autologous bone marrow rescue, and irradiation hold promise of better tumor control by overcoming the inaccessibility of the central nervous system to standard doses of chemotherapy. We review the pathology, clinical features, neuroimaging features, and current therapeutic concepts relative to brainstem glioma. The pediatric neurologist has a pivotal role in identifying and monitoring children with this malignancy.

Biopsy↗
PubMed1993

Parainfectious optic neuritis and encephalomyelitis. A report of two cases with thalamic involvement.

Two children developed mental status alteration and bilateral profound visual loss secondary to optic neuritis. The clinical picture was consistent with parainfectious encephalomyelitis. Magnetic resonance imaging showed bilateral involvement of the thalamus in both cases. In one case the thalamic involvement was solitary and was suspected initially to represent a primary thalamic neoplasm. This was ruled out by a stereotactic biopsy of the thalamus, which showed perivascular inflammation consistent with parainfectious encephalomyelitis. The clinical and neuroimaging findings improved significantly following corticosteroid administration. Several relapses occurred upon initial attempts at corticosteroid cessation.

Child, Preschool↗
PubMed1993

Juvenile xanthogranuloma of the corneoscleral limbus.

A 10-year-old boy had a slowly enlarging left limbal mass, extending into the corneal stroma, but not into the anterior chamber. The lesion was excised by lamellar sclerokeratectomy and subsequently confirmed histopathologically as a juvenile xanthogranuloma. Though rare, juvenile xanthogranuloma of the corneoscleral limbus should be considered in the differential diagnosis of limbal mass lesions extending into the cornea. Total resection is usually curative.

Child↗
PubMed1993

Bilateral isolated retrobulbar optic neuropathy in limited Wegener's granulomatosis.

Wegener's granulomatosis causes a variety of ophthalmologic disorders, some of which occasionally constitute the initial presentation of the disease. We describe a patient who presented with bilateral, isolated, consecutive, posterior optic neuropathy with light perception and no light perception vision. The patient had no other symptoms or signs of orbital disease. Investigations revealed cavitary lung lesions, positive antineutrophilic cytoplasmic antibody (ANCA) titers, subtle focal enhancement of the intracanalicular optic nerves on magnetic resonance imaging, and a confirmatory bronchial biopsy. This exceedingly rare ocular presentation of Wegener's granulomatosis may pose a diagnostic quandary.

Cyclophosphamide↗