Amnesia in a patient with lesions limited to the dorsomedial thalamic nucleus

Abstract

We describe a patient who suffered a thalamic stroke. MRI revealed bilateral lesions confined to the dorsomedial nucleus (DM), more extensive on the left than on the right. The only other damage evident was some slight atrophy of the mammillary bodies bilaterally. Neuropsychological tests revealed a long-lasting and severe deficit of both recall and recognition and some indication of frontal lobe dysfunction. Retrograde amnesia was thought to extend ～3 years premorbidly. This case provides strong evidence of a crucial role for the DM in normal memory functioning. The findings are discussed in relation to an hypothesis which postulates that the DM forms part of a memory system which plays an important role in item recognition in contrast to the hippocampal system (hippocampus, fornix, mammillary bodies and anterior thalamus) which is thought to be crucial for free recall and recognition of associative information.     

Eyelid tremor in a patient with a unilateral paramedian thalamic lesion

A patient with a circumscribed infarction of the right paramedian thalamus developed a tremor of both eyelids on voluntary eye closure. Co-registration of the magnetic resonance image to a stereotactic atlas of the human thalamus revealed that the lesion was confined to a small subgroup of paramedian nuclei, including the parvocellular part of the mediodorsal nucleus. It is concluded that this region provides inhibitory input to cortical and/or subcortical regions controlling eyelid movements. Voluntary eye closure may involve direct cortico-nuclear connections and indirect pathways through the paramedian thalamus, most probably through the mediodorsal nucleus.     

Impairment of memory and affect in a patient with reversible bilateral thalamic lesions due to internal cerebral vein thrombosis

A 39-year-old woman suffered from an extensive bilateral lesion in the region of the thalamus. The damage, caused by a primary thrombosis of the internal cerebral veins, turned out to be reversible to a considerable degree detected by repeated CT-and MR-imaging after 2, 4 and 9 months. In spite of the partial, structural recovery the patient remained severely impaired on both cognitive and affective levels. The key functions involved were an anterograde verbal and figural memory impairment, depressed arousal and attentional levels, affective flattening, lack of prosody and a depressive irritable mood. These findings illustrate that thalamic lesions of a certain extent not only influence memory functioning, but have in addition, severe consequences for emotional behavior.     

Electrophysiologic recordings in a patient with a discrete unilateral thalamic infarction

The electroencephalogram, and somatosensory and auditory evoked potentials were recorded from a patient, who, at necropsy, showed a restricted unilateral thalmic infarct involving predominantly the anterior and lateral thalamus. The electroencephalogram showed distinct monomorphic delta activity and a suppression of the alpha rhythm over the side of the lesion. Short latency somatosensory evoked potentials were present bilaterally; mid-latency somatosensory evoked potentials were absent ipsilateral to the lesion. Both mid-latency and long latency auditory evoked potentials were normal.     

Adult-onset autosomal recessive ataxia with thalamic lesions in a Finnish family

OBJECTIVE: To describe an unusual kindred with adult-onset ataxia and thalamic lesions detected by brain MRI. METHODS: The authors characterized clinical, laboratory, and pathologic features of the disease and sought linkage to previously recognized ataxia loci. RESULTS: Two sisters and a brother developed progressive ataxia, dysarthria, mild cognitive impairment, and sensorimotor neuropathy at age 30, combined with epilepsy in one sibling. MRI showed symmetric thalamic lesions, changes in brainstem gray matter, and white matter changes in the cerebellum. Autopsy in one of the patients revealed neuronal degeneration with a peculiar vacuolar change in thalamus, probably representing transsynaptic degeneration in response to deafferentation. Neuronal and secondary tract degeneration was observed in the spinal cord, cerebellum, and brainstem suggesting a spinocerebellar degeneration. The disorder appears to be transmitted as an autosomal recessive trait. Genetic and sequence analysis of the FRDA gene and comprehensive laboratory examinations excluded Friedreich's ataxia and other similar recessive diseases. CONCLUSION: Adult-onset recessive ataxia with bilateral thalamic lesions in this family may represent a distinct hereditary spinocerebellar ataxia.     

SPECT in a patient with postictal PLEDs: is hyperperfusion evidence of electrical seizure?

The pathophysiological relation between periodic lateralized epileptiform discharges (PLEDs) and epileptic seizures is not known and the exact causative mechanism of PLEDs still remains unclear. In this report, the authors present a case in which the EEG displayed PLEDs after a complex partial seizure. This patient, with a long history of complex partial seizures, had previously undergone right standard anterior temporal lobectomy with hippocampectomy, with a diagnosis of mesial temporal sclerosis. She had one complex partial seizure 72 days after operation and was admitted to hospital. Her brain MRI revealed changes due to temporal lobectomy and small residual posterior hippocampic anomalies. PLEDs over the right temporal lobe were seen in postictal EEGs and persisted for 4 days despite the patient's normal mental status and normal neurologic examination. Brain perfusion scintigraphy with Tc-99m-HMPAO during PLEDs was performed on the second day after the seizure, and right temporal hyperperfusion was detected. EEGs and scintigraphic imaging were repeated after cessation of PLEDs. The repeated brain scan displayed right temporal hypoperfusion. PLEDs during the postictal period may actually be an ictal pattern, and if hyperperfusion in the brain SPECT studies during PLEDs is seen, further aggressive antiepileptic drug therapy may be necessary in some cases.     

Somatosensory evoked potentials in patients with thalamic lesions

Summary Somatosensory evoked potentials (SEPs) were recorded in 20 patients with thalamic lesions confirmed by CT (10 with infarction, 10 with haemorrhage). The changes in SEP configuration are discussed in their relationship to clinical symptoms. Four types of SEP abnormality produced by thalamic lesion are distinguished: (1) FF type, (2) N20/P23 dissociation type, (3) N18/N20 false shift type, and (4) reduced early component type. It was shown that clinically similar lesions might produce different SEP patterns.     

Atypical postictal transient subcortical T2 hypointensity in a newly diagnosed diabetic patient with seizures

Common postictal MRI findings include transient cortical T2 hyperintensity, restricted diffusion, and gyral and/or adjacent leptomeningeal contrast enhancement. In certain uncommon pathological conditions, other signal abnormalities can be present, suggesting a different underlying pathogenic mechanism. We report the case of a 66‐year‐old man, recently diagnosed with diabetes mellitus type 2, presenting with new‐onset visual and auditory hallucinations, “absence” seizures, and repeated peaks of hyperglycaemia without hyperketonaemia or increased serum osmolarity. EEG confirmed epileptic discharges in the right temporal region and MRI showed vast subcortical T2 hypointensity in the right temporal lobe, without any cortical hyperintensity, restricted diffusion, or contrast enhancement. Subcortical signal abnormality and EEG discharges resolved after a month of follow‐up, with a small juxtacortical gliotic focus as a sequela. Peaks in hyperglycaemia have been reported to be responsible for T2 hypointense subcortical abnormalities through a proconvulsant mechanism linked to increased ketone body concentrations. Hyperosmolarity and hyperketonaemia were not evident in this case, however, transient accumulation of free radicals that alter the intercellular space can be considered the presumable cause of this finding. In summary, it is important to consider any unusual findings on postictal MRI in order to avoid errors in interpretation.     

Anatomico-clinical correlation in focal thalamic lesions

Summary The authors emphasize the interest of certain observations on account of the specificity of the symptoms and the discreteness of the lesions. In these cases, pathology in man can be considered acting as stereotaxic targets, and therefore valuable for the understanding of thalamic functions.Vascular lesions are the most useful being topographically precise. Observations which can be used are indeed rare, but their value is incontrovertible. The authors describe successively partial sensory syndromes, cerebellar ataxia and mental disorders, which are in fact the only parts of thalamic symptomatology in which exceptional cases permit clinico-anatomical focal correlation.Partial sensory disorders can be localized to the face, the upper limb, the lower limb; they can have a cheiro-oral, cheiro-podo-oral, or pseudo-radicular topography. Their study leads to a somatotopical mapping of the sensory relay nuclei of the thalamus in man. In some cases taste disorders are added to somatosensory disorders. This has been explained by a gustatory thalamic center (in the medial part of the posterior ventral nucleus) close to the representation of the tongue in the somatosensory center.Certain observations prove the existence of a cerebellar component in thalamic ataxia. These cases corroborate what is known of the fan-like termination of cerebellar (brachium conjunctivum) afferents in the thalamus. The somatotopical organisation of the afferents may be discussed.As far as mental disturbances are concerned, clinico-anatomical correlation can not have such a pin-point precision. They have, however, confirmed the existence of a thalamic dementia especially when medial nuclei are interested. Moreover it can be demonstrated that Papez's hippocampo-mammillary circuit has an important relay in nucleus ventralis anterior. The lesions giving rise to mental disorders are particularly important, insofar as no such conclusive evidence can be elicited from experimental observations.Translated from a paper presented at the Joint Meeting of the German and French Neurological Societies, Munich 1970.     

Chronic thalamic stimulation in a patient with spinocerebellar ataxia type 2.

We report on a patient with spinocerebellar ataxia type 2 (SCA 2) with an unusual clinical presentation, including severe, disabling resting and action tremor and the successful treatment of this tremor syndrome with chronic thalamic stimulation. Using [(123)I]beta-CIT single photon emission computed tomography, we document a marked degeneration of the nigrostriatal dopaminergic system in SCA 2.     

Neurosurgery in a patient with Creutzfeldt-Jakob disease after pituitary derived growth hormone therapy in childhood.

The case of a young man who had previously received pituitary derived growth hormone for treatment of radiation induced growth hormone deficiency is reported. He underwent neurosurgery for presumed recurrence of a posterior fossa tumour but was subsequently shown to have Creutzfeldt-Jakob disease, confirmed on necropsy. The risk of transmission of Creutzfeldt-Jakob disease by neurosurgical instruments is discussed. Since the occurrence of this case the Department of Health have issued guidelines concerning neurosurgery and ophthalmic surgery in patients who have previously received treatment with pituitary derived growth hormone and may therefore be at risk of developing Creutzfeldt-Jakob disease. Surgical instruments used on such patients should under no circumstances be reused, and should be destroyed after use.     

A case of theophylline-associated seizures with postictal fever and postictal pleocytosis

We report a 70-year-old man who developed theophylline-associated seizure with postictal fever and postictal pleocytosis. He was admitted to our hospital for a left hemiconvulsion lasting for two hours. The concentration of theophylline was high (21.6ng/ml), and electroencephalogram demonstrated periodic lateralized epileptiform discharges. Diffusion-weighted magnetic resonance imaging showed high signal intensity lesions in the right cingulated gyrus, insula and thalamus. Temperature above 38.0° was detected 5.5 hours after seizure and lasted for 60 hours. Cerebrospinal fluid (CSF) analysis on day 2 demonstrated pleocytosis (62/uL) with a predominance of polymorphonuclear leukocytes (90%). Temperature and CSF pleocytosis subsided after sedation. Intracranial inflammatory or infectious disease is the first consideration in epilepsy with fever and CSF pleocytosis, and then diagnosis of postictal fever and postictal pleocytosis should be made only by rigorous exclusion of that possibility.     

Ipsiversive partial ocular tilt reaction in a patient with acute paramedian thalamic infarctions

The ocular tilt reaction (OTR) consists of skew deviation, ocular torsion and head tilt. A 54-year-old woman developed sudden onset of vertical diplopia. On primary gaze, there was skew deviation with the left eye higher than the right eye. The photography of fundus disclosed 15 degrees of excyclotropia of the right eye and 20 degrees of incyclotropia of the left eye. There was no motor deficit, sensory impairment, ataxia or changes in consciousness. Brain MRI, including T2WI, FLAIR and DWI, revealed two lesions of high signal intensities in bilateral paramedian thalamus, with the much larger and brighter one on the right side. These findings constituted an ipsiversive partial OTR, i.e. skew and torsion toward the side of the lesion. OTR as the only manifestation of paramedian thalamic stroke is rare. A previous report by Dieterich and Brandt indicated that if an OTR occurred in a paramedian thalamic infarct, there should be concurrent ischemia of the interstitial nucleus of Cajal, and it was always contraversive. In contrast, the lesions in our case were quite localized in the paramedian thalamus, not extending into the midbrain. In addition, this report demonstrated an OTR could be ipsiversive under such conditions, opposite to the direction mentioned in previous reports.