Lingual seizures

Epileptic manifestations, pathophysiology, and imaging characteristics of non-ketotic hyperglycaemia: a review of the literature and a report of two cases with irreversible cortical vision loss

The purpose of this review is to create more awareness regarding the epileptic manifestations of non-ketotic hyperglycaemia, which are not widely recognised, and to assist understanding of the pathophysiology involved. Given that type II diabetes is one of the common causes of morbidity worldwide, it is important to appreciate the various neurological manifestations of non-ketotic hyperglycaemia.Here, I present two cases and review the existing literature. Both patients developed irreversible vision loss, which is a novel finding because only transient visual defects have previously been reported. The review includes a detailed discussion of the pathophysiology and characteristic magnetic resonance imaging (MRI) findings of patients with defects in cerebral lobar regions, which were associated with a variety of clinical manifestations. These manifestations can be ascribed to epileptic phenomena involving various parts of the cerebrum.Hyperglycaemia can lead to the irreversible loss of vision. Early diagnosis and treatment on the basis of the clinical features and characteristic MRI findings are important to avoid an epilepsia partialis continua-like state and irreversible visual impairment.

Impaired corticolingual pathways in patients with or without dysarthria after acute monohemispheric stroke

The occurrence of dysarthria is not infrequent in stroke but little is known about its pathophysiology. The aims of the present study were to assess the central motor innervation of the tongue in normal adults using transcranial magnetic stimulation (TMS) and to compare this with that seen in stroke patients with or without dysarthria. The study included 46 patients with acute monohemispheric stroke due to occlusion of the territory of the middle cerebral artery as documented by CT brain scan (26 patients with dysarthria and 20 patients without dysarthria). Forty-five (age and sex matched) normal volunteers served as controls. Corticolingual pathways were assessed for each subject after TMS of each hemisphere. TMS over the motor cortex of healthy subjects elicited consistent ipsilateral and contralateral lingual responses. The ipsilateral response was usually smaller and approximately 73% of the amplitude of the contralateral response. The cross talk between the two halves of the tongue as estimated after unilateral electrical stimulation of hypoglossal nerve gave a contra/ipsi ratio of 36%, which was significantly smaller than the ratio seen after cortical stimulation (CL). For the patients, with or without dysarthria, motor evoked potential (MEP) latencies (ipsilateral and contralateral) were significantly prolonged after stimulation of affected hemisphere compared with the non-affected hemisphere or the control group (P< 0.001). MEP amplitudes were significantly smaller in hemiplegic patients with dysarthria compared to patients without dysarthria. In patients without dysarthria stimulation of the unaffected hemisphere tended to evoke responses that were of similar size on both sides. There were no significant associations between neurophysiological parameters and side of infarction. We conclude that interruption of the corticolingual pathways is frequent in stroke patients with or without dysarthria. The ability of unaffected hemisphere to evoke responses in the side contralateral to the lesion may relate to the absence or presence of dysarthria.

Seizure's outcome after cortical resections including the face and tongue rolandic areas in patients with refractory epilepsy and normal MRI submitted to subdural grids' implantation

PURPOSE

To study the seizure's outcome in patients with refractory epilepsy and normal MRI submitted to resections including the rolandic cortex.

METHODS

Four adult patients were studied. All patients had motor or somatosensory simple partial seizures and normal MRI and were submitted to subdural grids' implantation with extensive coverage of the cortical convexity (1 in the non-dominant and 3 in the dominant hemisphere).

RESULTS

ECoG was able to define focal areas of seizures' onset in every patient. All patients were submitted to resection of the face and tongue motor and sensitive cortex; two patients had resections including the perirolandic cortex and 2 had additional cortical removals. Three patients are seizures' free and one had a greater then 90% reduction in seizure frequency.

CONCLUSION

Resections including the face and tongue rolandic cortex can be safely performed even within the dominant hemisphere.

Motor evoked potentials in unilateral lingual paralysis after monohemispheric ischaemia

OBJECTIVES

The occurrence of a lingual paralysis after unilateral upper motor neuron lesions is an infrequent clinical phenomenon, and the underlying pathophysiological mechanisms are poorly understood. We studied the cortical motor representations of ipsilateral and contralateral lingual muscles in healthy controls and in a selected group of stroke patients, to clarify the variable occurrence of a lingual paralysis after recent monohemispheric ischaemia.

METHODS

A special bipolar surface electrode was used to record the ipsilateral and contralateral compound muscle action potentials (CMAPs) from the lingual muscles after transcranial magnetic stimulation (TMS) of the human motor cortex and peripheral electrical stimulation (PES) of the hypoglossal nerve medial to the angle of the jaw. Four patients with a lingual paralysis (group 1) and four patients with symmetric lingual movements (group 2) after monohemispheric first ever stroke were studied and compared with 40 healthy controls.

RESULTS

In controls, TMS of either hemisphere invariably produces CAMPs in the ipsilateral and contralateral lingual muscles, elicited through crossed and uncrossed central motor pathways, respectively. In the 40 healthy controls, TMS of either hemisphere elicited CMAPs of significantly greater amplitudes and shorter onset latencies from the contralateral muscles compared with the ipsilateral responses (p<0.0001). In the patient groups, TMS of the affected hemisphere failed to evoke any CMAP from either lingual side; TMS of the unsevered hemisphere always produced normal ipsilateral and contralateral responses, irrespective of whether the ipsilateral muscles were paralysed or not.

CONCLUSIONS

Bilateral crossed and uncrossed corticonuclear projections are invariably existent in humans. After unilateral interruption of these pathways, some people do exhibit a lingual paralysis whereas others do not. The development of a central lingual paralysis is most likely dependent on the ability of the unsevered hemisphere to utilise the pre-existent uncrossed motor projections. The variable availability of these pathways among individual subjects is in good agreement with the inconstant occurrence of a lingual paralysis after restricted monohemispheric lesions.

Gaze-evoked visual seizures in nonketotic hyperglycemia

Focal motor seizures are commonly a symptom of nonketotic hyperglycemia (NKH). Posture-induced motor seizures are less common but have been reported in some patients with this disorder. We report the first case of gaze-evoked sensory (visual) seizures in nonketotic hyperglycemia. Both seizures and ictal EEG findings disappeared shortly after hyperglycemia was corrected.