PubMed Health⌕ Search

Biomedical subjects

N Vijayan

Publications and source records attributed to N Vijayan.

At least 19 recordsLinked to original sources
PubMed2006

Growth and characterization of organic nonlinear optical crystal of 1-chloro-2,4-dinitrobenzene (CDNB).

Organic nonlinear optical crystal of 1-chloro-2,4-dinitrobenzene has been successfully grown by low temperature solution growth technique. Good optical quality single crystals of size 28 mm x 11 mm x 5mm are obtained. Grown crystals were subjected to X-ray powder diffraction analysis, FT-IR, FT-Raman, proton nuclear magnetic resonance (PNMR) and etching studies. Thermal properties of the grown crystals were studied by thermo gravimetric analysis (TGA) and differential thermal analysis (DTA). UV-vis studies show the cutoff wavelength is less than 400 nm. Nonlinear optical property of the crystal was studied by Kurtz powder technique using Nd:YAG laser and the crystal exhibits second harmonic generation property.

Crystallization↗
PubMed2000

Spinal cord infarction during use of zolmitriptan: a case report.

A 50-year-old woman with a history of migraine without aura, predominantly occurring around her menstrual periods, developed a spinal cord lesion following the use of zolmitriptan. The partial lesion of the cord at T7 predominantly involved the spinothalamic pathways on the left side. Clinical features suggested that the lesion was an ischemic infarct, and this was confirmed by an MRI scan. There were no other known risk factors for vascular disease. There has been mild improvement of her symptoms, but most of the symptoms did not resolve. There are isolated case reports of stroke secondary to the use of triptans, however, this is the first case of spinal cord infarction reported following the use of this group of drugs. The temporal relationship suggests that the spinal cord infarction may be related to the use of zolmitriptan.

Female↗
PubMed1995

The sympathetic innervation of the eyes and face: a clinicoanatomic review.

Most of the details regarding the course of the sympathetic fibers to human ocular structures are based on anatomical and physiological studies in lower animals. While studying a clinical problem involving pericarotid sympathetic fibers, it became obvious that these animal observations cannot adequately explain the findings in human diseases affecting these pathways. An attempt was made, therefore, to clarify this situation. We were able to gather enough information from human clinical and experimental studies, from our own clinical observations, and from our cadaver dissections to conclude that these pathways are somewhat different from those which are usually described in the literature. Based on this information, we conclude that 1) the oculosympathetic fibers in man do not course through the tympanic plexus and/or trigeminal ganglion, and 2) the sweat glands of the face receive their innervation from both internal and external carotid sympathetic plexuses. We also have suggestive, but inconclusive, evidence regarding the final mode of distribution of these fibers to the dilator of the pupil and the smooth muscle portion (deep layer) of the levator palpebrae superioris muscle (superior tarsal muscle).

Animals↗
PubMed1995

Postoperative headache in acoustic neuroma.

Recently, it has become obvious that disabling postoperative headache is a major problem with acoustic neuroma surgery. A questionnaire was used to retrospectively evaluate the incidence, clinical features, prognosis and possible therapeutic measures of this particular form of headache. Forty-two percent (42%) of patients had some headache prior to surgery but this was not a major complaint. After surgery, 75% of patients experienced headache. Only 24% had complete relief of headache. A very gradual improvement of the pain occurred in 32%. Pathogenesis remains unclear, but clinical characteristics of the headache suggest a combination of tension-type, neuralgic and vascular components. Postoperative pain occurs mostly around the surgical site suggesting that this type of headache is the result of surgical trauma. A prospective long-term study is needed to delineate this condition further. Some therapeutic suggestions are offered.

Adult↗
PubMed1995

Valproic acid treatment of chronic daily headache.

The efficacy of valproic acid in the treatment of intractable chronic daily headache, unresponsive to traditional prophylactic medications, was examined prospectively in 16 patients. Dosage of the medication was adjusted to maintain serum valproic acid levels between 50 and 100 micrograms/mL, provided there were no significant side effects at that level. Valproic acid prophylaxis was of some benefit in only 2 of 16 patients. One of these two patients discontinued therapy due to side effects. Eight of the 16 patients reported side effects which included nausea, diarrhea, anorexia, lethargy, sleepiness, confusion, blurred vision, and decreased libido. In conclusion, valproic acid was not effective in controlling chronic daily headache in the majority of patients in whom conventional therapy had failed, and 50% of patients reported side effects. There is a significant disparity in the reported efficacy of this drug in treating chronic daily headache. This disparity is most likely due to the poorly-defined nature of this variety of headache. It is, therefore, recommended that more stringent definition of this disorder be developed before therapeutic regimens are evaluated.

Adult↗
PubMed1995

Headache.

Explore the source record for details and available documents.

Humans↗
PubMed1993

Head band for migraine headache relief.

Application of an ice pack and local scalp pressure are the most commonly used non-pharmacological methods for temporary relief of migraine headache pain. An elastic band secured around the head with Velcro and firm rubber discs inserted under the band was used to apply local pressure over the area of maximum pain in 25 patients with migraine headache. Three headaches were studied in each patient. Two patients dropped out because of local tenderness which prevented them from using the band. The 23 remaining patients used the band in a total of 69 headaches. Pain relief was monitored for 30 minutes at 10 minute intervals. Sixty headaches (87%) were relieved. Nine headaches (13%) were not improved. Sixty-seven percent of those who improved (40 headaches) had relief of over 80%, twenty-five percent (15 headaches) improved between 50-60% and eight percent (5 headaches) had less than 50% improvement. Pain severity steadily increased when the band was released. Temporary relief of pain from mechanical compression of the scalp supports the possibility that at least part of the pain in migraine headache originates from dilated blood vessels in the scalp.

Equipment Design↗
PubMed1992

Symptomatic chronic paroxysmal hemicrania.

A patient with chronic paroxysmal hemicrania (CPH) associated with a gangliocytoma growing from within the sella turcica is reported. This tumor displaced the floor of the third ventricle and surrounded the internal carotid artery on the same side as the headache. Partial removal of the tumor followed by radiation resulted in amelioration of headache. The anatomical location of the tumor and its possible relationship to the pathogenesis of CPH is discussed.

Adult↗
PubMed1990

Cluster headache and vertigo.

The term "cluster vertigo" was originally used by Gilbert to describe episodes of vertigo in patients with Ménière's syndrome. Since these patients also had co-existing cluster headache, he suggested that both disorders could have had a common pathophysiology. There is no evidence in the literature for an increased incidence of Ménière's syndrome in cluster headache patients, so the argument that cluster headache and Ménière's syndrome may have a common pathogenesis cannot be supported. Subsequent authors have used the term "cluster vertigo" to denote a variant form of cluster headache and have confused the matter further. This was not the intention of the original author. The terminology is misleading and should not be used to describe a sub-type of cluster headache. A case of cluster headache with accompanying vertigo is described as a contrast to the patients described by Gilbert in whom headache and episodes of vertigo occurred independently.

Adult↗
PubMed1989

Visual field loss in migraine.

Ocular symptoms are a common, though transient, initial component of migraine. Although permanent visual loss has been reported in a limited number of patients, detailed evaluations of the visual field using current techniques have not been conducted. This study examined the prevalence of visual field loss in patients with migraine, using an automated static perimeter. All patients had at least a 2-year history of migraine (as diagnosed by a neurologist) and no ocular problems (by history or as determined by a visual screening examination consisting of acuity, intraocular pressure [IOP], and evaluation of the disc). The authors' results for 60 migraine patients showed that 21 (35%) had some form of visual field abnormality (P less than 0.05). The prevalence of visual field loss was greater with increasing age and duration of disease. These results suggest that visual field loss from migraine may be more common than previously considered. This information also may be useful in elucidating the relationship between migraine and certain vascular conditions of the eye.

Adolescent↗
PubMed1989

Site of injury headache.

Wolff described three types of post-traumatic headaches (PTH). In type II PTH, the pain is located at the site of injury. Local soft tissue trauma and direct damage or entrapment of sensory nerves in the scar tissue are thought to be responsible for this type of headache. It is often difficult to study the neurological and autonomic changes in the scalp in these patients. We report here 8 patients with PTH in whom the site of injury was on the face thereby allowing us to evaluate the local neurological changes with greater accuracy. The results of this study corroborate Wolff's view of the pathogenesis of type II or "site of injury" PTH.

Adult↗
PubMed1987

Episodic paroxysmal hemicrania?

Cyclic remissions in chronic paroxysmal hemicrania (CPH) have been considered to be transitory phenomena inevitably leading to the chronic stage. This conclusion has precluded the possibility of paroxysmal hemicrania having an episodic counterpart. Six case histories presented here establish the persistence of cyclic patterns for a mean of 23 years of illness, thus suggesting that the "pre-CPH" nomenclature may be presumptive, and, further, provide evidence for another classification: episodic paroxysmal hemicrania.

Adult↗