Focal Central Nervous System Lesions Research Articles

Gabapentin-induced myoclonus: a case report

Objective: To present a case of myoclonus secondary to gabapentin use in a patient with no epilepsy or renal disease. Background: Myoclonus may be linked to a variety of causes, including epilepsy, postanoxic brain injury, metabolic encephalopathies and focal central nervous system lesions. Various drugs also have been reported to induce myoclonus. Gabapentin-induced myoclonus has been reported previously, especially in cases with impaired renal function or epilepsy. Method: Case report Results: A 68-year-old male presented with hand tremors starting 2 weeks after the initiation of 1800 mg daily gabapentin recommended for distal neuropathic pain. Examination revealed bilateral action-induced clonus in the hands. His mental status was normal, and there was no weakness. Ankle reflexes were normal, and plantar reflexes were flexor. There was mild hypesthesia of the distal lower extremities. Routine blood tests including urea, creatinine, electrolytes and thyroid function tests were normal. Gabapentin levels were not determined. Gabapentin was discontinued, and his symptoms spontaneously resolved 2 days after discontinuation of gabapentin. Conclusions: The close time relationship between gabapentin initiation and onset of myoclonus, and the rapid resolution of symptoms after withdrawal of the drug suggested that gabapentin played a causative role in our patient. Pathophysiological mechanisms of gabapentin-induced myoclonus remain poorly understood. It has been suggested that the serotonin neurotransmitter system may be involved in the pathogenesis. Administration and dose escalation of gabapentin should be performed with caution, and gabapentin should be always considered as a potential etiology for myoclonus.

Visual Hallucinations in Mania

Visual hallucinations occur in a wide variety of neurological and psychiatric disorders, including toxic disturbances, drug withdrawal syndromes, focal central nervous system lesions, migraine headaches, blindness, schizophrenia, and psychotic mood disorders. Visual hallucinations are generally assumed to characteristically reflect organic disorders and are very rare in affective disorders. Here, we present a case of visual hallucinations in a young female with bipolar illness during the manic phase.

Could sudden cardiac death in epilepsy be related to the occurrence of thalamic dysfunction or anatomic change?

Sudden unexpected death in epilepsy (SUDEP) is the most important direct epilepsy-related cause of death in people with chronic epilepsy. Its physiopathology is still unknown; however, the most commonly suggested potential mechanisms involve cardiac or respiratory abnormalities. As the anatomical substrate of epileptic activity in the central nervous system (CNS) shows a direct relationship with cardiovascular alterations, this may suggests that patients with epilepsy associated with focal CNS lesions may be at particular risk of SUDEP. Currently, experimental and clinical data support an important role for thalamic nuclei in the behavioural manifestations, initiation and propagation of seizures. In view of the above findings, we purpose that SUDEP, at least in some cases, could be related to the occurrence of thalamic dysfunction or anatomic change.

SPECT Thallium-201 Combined with Toxoplasma Serology for the Presumptive Diagnosis of Focal Central Nervous System Mass Lesions in Patients with AIDS

Objective: To determine the utility of brain thallium-201 single photon emission computerized tomography (Tl-201 SPECT) combined with Toxoplasma serology for the diagnosis of focal CNS lesions in patients with AIDS.Methods: Sixty-one consecutive HIV-infected patients with focal CNS lesion(s) on head computed tomography (CT) or MRI scan who underwent brain Tl-201 SPECT and serum Toxoplasma serology were evaluated, retrospectively. Thallium-201 uptake ratios were calculated by comparing lesion activity to contralateral scalp activity. Diagnoses were made by a combination of histology, serology, PCR, and empirical response to therapy. Toxoplasma serologies (IgG IFA) were compared in the patients with central nervous system (CNS) toxoplasmosis and those without CNS toxoplasmosis.Results: Fifty-six patients were evaluable and a definitive diagnosis was made in 38 patients: toxoplasmosis (17), lymphoma (14), PML (three),Aspergillus (one), tuberculoma (one), Cryptococcus (one), varicella-zoster virus (one). Patients with lymphoma had significantly higher lesion/contralateral scalp ratios compared to patients without lymphoma: 1.03 vs. 0.67,P <0.05. Using a cut-off of 0.90 for the lesion/scalp uptake ratios (based on analysis of ROC curves) the sensitivity and specificity for the diagnosis of lymphoma were 86% and 83%, respectively. Serum Toxoplasma IgG titres were significantly higher in patients diagnosed with toxoplasmosis compared to those with a diagnosis other than toxoplasmosis, 1:5444 vs. 1:15, P<0.05. Only one patient with confirmed toxoplasmosis had a Toxoplasma serology <1:256, while no patients without toxoplasmosis (including all lymphoma patients) had serologies >1:256.Conclusions: In a series of HIV-infected patients, Tl-201 SPECT was able to accurately differentiate primary brain lymphoma from other causes of focal CNS lesions in most patients; however, both false positive and false negative results occurred. By combining Tl-201 SPECT with serumToxoplasma IgG, diagnostic accuracy was improved.

Differentiation of central nervous system lesions in AIDS patients using positron emission tomography (PET).

To determine if positron emission tomography (PET) imaging using F-18 fluorodeoxyglucose (FDG) can accurately distinguish between malignant and infectious central nervous system (CNS) mass lesions in patients with human immunodeficiency virus (HIV) infection, a prospective case series of 18 patients with HIV infection and focal CNS lesions on computed tomography (CT) or magnetic resonance (MR) scans was analysed. The patients were divided into 3 groups based on biopsy results, serology and response to therapy. Group 1 consisted of 8 patients with infectious lesions (4 with toxoplasmosis, 2 with neurosyphilis, 2 with progressive multifocal leukoencephalopathy (PML)). Group 2 consisted of 5 patients with biopsy proven CNS lymphoma. Group 3 consisted of 5 patients with presumed CNS lymphoma. Patients underwent FDG-PET studies as an adjunctive diagnostic procedure. The metabolic activity of each patient's lesion was graded using both a qualitative visual score and a semi-quantitative count ratio comparing the lesion with contralateral brain. CNS lesions diagnosed as lymphomas had statistically higher visual scores (P = 0.001) and count ratios (P = 0.002) than CNS lesions diagnosed as infections. FDG-PET could accurately differentiate lymphoma from infections in 16 of 18 cases. Two cases of PML had high metabolic activity and could not be differentiated from lymphoma. FDG-PET shows great promise in differentiating lymphoma from infectious lesions in the CNS of patients with HIV infection. If larger prospective studies confirm this impression, more specific and rapid treatment of CNS lesions could be performed and perhaps obviate the need for brain biopsy in many cases.

The neuropathology of pediatric acquired immunodeficiency syndrome.

Central nervous system disease has emerged as an important manifestation of acquired immunodeficiency syndrome in both the adult and pediatric populations, with neurologic abnormalities occurring in up to 90% of pediatric patients in some series. Neuropathologic studies, based primarily on the autopsy, have provided valuable insights into the spectrum and pathogenesis of acquired immunodeficiency syndrome-associated neurologic disorders, including primary human immunodeficiency virus encephalopathy and as the spectrum of infectious, neoplastic, and cerebrovascular diseases that may complicate the course of acquired immunodeficiency syndrome. Progressive encephalopathy represents the single most common neurologic disorder in pediatric acquired immunodeficiency syndrome and appears to be caused in most cases by direct infection in brain parenchyma by human immunodeficiency virus. Central nervous system lymphoma and cerebrovascular disease continue to account for most focal central nervous system lesions in the pediatric population. In contrast to adults with acquired immunodeficiency syndrome, opportunistic central nervous system infections remain relatively uncommon in the pediatric population. Our understanding of acquired immunodeficiency syndrome-associated neurologic disease remains far from complete. A plea is made for regular postmortem examination of the central nervous system in all patients dying with human immunodeficiency virus infection.

Use of CT and MR imaging to distinguish intracranial lesions and to define the need for biopsy in AIDS patients

To explore the potential usefulness of imaging studies in the diagnosis of focal central nervous system (CNS) lesions associated with acquired immunodeficiency syndrome (AIDS), the authors retrospectively examined the radiographic studies of 149 AIDS patients who presented with signs and symptoms of the three most common focal CNS lesions. Of these patients, 74 (50%) had Toxoplasma abscesses, 45 (30%) had primary CNS lymphoma, and 30 patients (20%) had progressive multifocal leukoencephalopathy (PML). Magnetic resonance (MR) imaging was more sensitive than computerized tomography (CT) in detecting lesions, especially in cases of PML. Whereas CT was unable to distinguish mass lesions caused by toxoplasmosis from those caused by lymphoma, 71% of the solitary lesions seen on MR images were lymphomas. These results indicate that empirical treatment for toxoplasmosis, the most common initial treatment for AIDS patients with neurological symptoms stemming from mass lesions, is not likely to be successful for patients with solitary lesions on MR images. Rather, early biopsy is advisable. If the presence of lymphoma is confirmed, the rapid initiation of treatment can allow prolonged high-quality survival.

Assessing visual memory disorders.

A new test of visuospatial learning and memory, the Biber Figure Learning Test (BFLT), was administered to patients with right- (n=19) and left- (n=20) hemisphere cerebrovascular accidents, severe amnesics (n=11), and healthy middle-aged and elderly controls (n=42). The findings support the usefulness of the BFLT for assessing components of visual memory impairment in patients with focal central nervous system lesions