Mechanism of tonic spasms in West syndrome viewed from ictal SPECT findings

Non-invasive, multimodal analysis of cortical activity, blood volume and neurovascular coupling in infantile spasms using EEG-fNIRS monitoring

Although infantile spasms can be caused by a variety of etiologies, the clinical features are stereotypical. The neuronal and vascular mechanisms that contribute to the emergence of infantile spasms are not well understood. We performed a multimodal study by simultaneously recording electroencephalogram and functional Near-infrared spectroscopy in an intentionally heterogeneous population of six children with spasms in clusters. Regardless of the etiology, spasms were accompanied by two phases of hemodynamic changes; an initial change in the cerebral blood volume (simultaneously with each spasm) followed by a neurovascular coupling in all children except for the one with a large porencephalic cyst. Changes in cerebral blood volume, like the neurovascular coupling, occurred over frontal areas in all patients regardless of any brain damage suggesting a diffuse hemodynamic cortical response. The simultaneous motor activation and changes in cerebral blood volume might result from the involvement of the brainstem. The inconstant neurovascular coupling phase suggests a diffuse activation of the brain likely resulting too from the brainstem involvement that might trigger diffuse changes in cortical excitability.

The usefulness of subtraction ictal SPECT and ictal near-infrared spectroscopic topography in patients with West syndrome

The recent findings on subtraction ictal SPECT and ictal near-infrared spectroscopic topography in patients with West syndrome were summarized and its availability for presurgical evaluation was discussed. The subtraction ictal SPECT study in patients with West syndrome demonstrated the cortical epileptic region and subcortical involvement, which may consist of epilepsy networks related to the spasms. Moreover, subtraction ictal SPECT may have predictive power for short-term seizure outcome. Patients with a symmetric hyperperfusion pattern are predicted to have a better seizure outcome, whereas patients with asymmetric hyperperfusion pattern may develop poor seizure control. Importantly, asymmetric MRI findings had no predictive power for seizure outcome. Multichannel near-infrared spectroscopic topography applied to the patients with West syndrome detected an increase in regional cerebral blood volume in multiple areas which were activated either simultaneously or sequentially during spasms. Topographic changes in cerebral blood volume were closely correlated with spasm phenotype, suggesting that the cortex is involved in the generation of spasms. In conclusion, subtraction ictal SPECT may be considered as a useful tool for presurgical evaluation of patients with West syndrome and investigation of the pathophysiology of spasms. The ictal near-infrared spectroscopic topography should be more investigated to see if this is useful tool for presurgical evaluation.

Transient left temporal lobe lesion in Menkes disease may influence the generation of tonic spasms

We report a 7-month-old boy with Menkes disease who presented West syndrome. Magnetic resonance imaging (MRI) revealed atrophy of the frontal and parietal lobes, subdural hematoma on the right side, and left temporal lobe lesion (low intensity in T1-weighted imaging (T1-WI), high intensity in T2-weighted imaging (T2-WI) and low intensity in diffusion-weighted imaging (DW-I)) at 7 months of age. The apparent diffusion coefficient (ADC) was 1.68×10(-3)mm(2)/s in the left temporal lobe lesion and 1.15×10(-3)mm(2)/s on the contralateral side. (1)H-magnetic resonance spectroscopy ((1)H-MRS) revealed a decrease in N-acetylaspartate/(creatine+phosphocreatine) (NAA/Cr) (0.71) and a lactate peak in the left temporal lobe lesion. At 8 months of age, the left temporal lobe lesion disappeared, the ADC of this lesion was within the normal range (1.10×10(-3)mm(2)/s), and (1)H-MRS revealed a slight increase in NAA/Cr (1.12) and disappearance of the lactate peak. We suspected that the transient temporal lobe lesion in Menkes disease was mainly vasogenic edema. Electroencephalography (EEG) revealed left hemisphere dominant hypsarrhythmia and slowing in the left hemisphere. Ictal EEG revealed generalized slow wave burst with P3, T3 spike antecedence and the antecedent spike was consistent with left temporal lobe lesion. After disappearance of the left temporal lobe lesion, tonic spasms disappeared and EEG findings improved. In this case, the clinical course and ictal EEG suggested that epileptic activity from the left temporal lobe lesion may have given rise to tonic spasms.

Role of single photon emission computed tomography in epilepsy

Molecular imaging with ictal single photon emission computed tomography (SPECT) is an established functional imaging modality for the presurgical evaluation of patients with refractory partial onset seizures. SPECT coregistered on to the MRI has greater sensitivity to identify the ictal onset zone. Ictal SPECT should always be interpreted in the context of other presurgical investigations. Ictal SPECT is sensitive method for the lateralization of TLE, but ictal SPECT is more sensitive when MRI is normal. Ictal SPECT and interictal PET are complementary to each other in lateralizing the side in patients with TLE and normal MRI. In extratemporal epilepsy, ictal SPECT will guide the placement of surface grid and depth electrodes.

Patients with West syndrome whose ictal SPECT showed focal cortical hyperperfusion

To clarify the mechanism of clustered spasms in West syndrome (WS), we examined ictal SPECT and EEG, as well as those during the interictal period, in three patients with symptomatic WS who had apparent focal cerebral lesions. For ictal SPECT and EEG, we monitored the patients with EEG, and as soon as we noticed the occurrence of clustered spasms clinically and electroencephalographically, [(99m)Tc]ECD was injected intravenously and flushed thoroughly with saline. In these three patients, regional cerebral blood flow (rCBF) increased during ictus and decreased during the interictal period in the area that coincided with the focal cerebral lesion recognized by CT/MRI. The ictal hyperperfusion of bilateral basal ganglia was also detected in two of the three patients. The ictal EEG showed a diffuse slow wave complex corresponding to a clinical spasm. The sharp waves that preceded the diffuse slow wave complex and the spasm appeared in the same area in which rCBF increased during ictus. None of the patients showed partial seizure before or after clustered spasms clinically or electroencephalographically during the ictal SPECT study. Secondary generalization from a cerebral focus may explain the mechanism of spasms in these patients with WS: focal cortical discharge may primarily generate clustered spasms and trigger the brainstem and basal ganglia structures to produce spasms.

Dynamic cortical activity during spasms in three patients with West syndrome: a multichannel near-infrared spectroscopic topography study

PURPOSE

To investigate spatial and temporal cortical activity during clusters of naturally occurring epileptic spasms in patients with West syndrome (WS) by using multichannel near-infrared spectroscopy (mNIRS).

METHODS

Conventional magnetic resonance imaging (MRI) and interictal and ictal single-photon emission computed tomography (SPECT) were carried out in three patients with WS. Thereafter, cortical hemodynamics during naturally occurring epileptic spasms were measured by mNIRS with simultaneous video/electroencephalographic (EEG) monitoring.

RESULTS

Ictal SPECT revealed multiple hyperperfused areas within the cortex. With the use of mNIRS, an increase in regional cerebral blood volume (CBV) was observed in these areas, which is representative of cortical activation. The increase in CBV was accompanied by an increase in the concentrations of both oxy- and deoxyhemoglobin. The following heterogeneous regional changes in CBV during ictus were observed: (a) transient increases that were synchronized with spasms; (b) a gradual increase during an ictal event that fluctuated in synchrony with spasms; and (c) a combination of transient and gradual increases. An increase in regional CBV occurred in multiple areas that were activated either simultaneously or sequentially during an ictal event. Topographic changes in CBV were closely correlated with the phenotype of the spasm.

CONCLUSIONS

During ictal events, multiple cortical areas were activated simultaneously or sequentially. The pattern of cortical activation closely affected the phenotype of the spasm, which suggested that the cortex was involved in the generation of spasms.

Leigh syndrome associated with West syndrome

Leigh syndrome (LS) (sub-acute necrotizing encephalomyelopathy) is characterized by symmetric brain lesions occurring mainly in the basal ganglia and associated with variable clinical manifestations such as hypotonia, psychomotor retardation, and feeding difficulties. Patients with LS may develop seizures. Only three patients with LS have been identified in the literature as having West syndrome (WS). We have seen 12 children with LS in the past 20 years, and noticed that as many as five of them developed WS. This report discusses five LS children with WS, comparing them with seven LS children without WS. In all five patients, infantile spasms developed after LS had become evident, in addition to other type(s) of seizures. The onset of LS in all the patients with WS was before 10 months of age. Although not statistically proven, early onset of LS, spasticity, nystagmus, apnea, poor feeding, and cardiac problems seemed to be associated with the development of WS. We were not able to conclude that certain types of symptoms or examination results of patients with LS indicated the development of WS. The association of LS with WS did not markedly influence the prognoses of the children. WS may not be a rare complication of LS, especially in infants under 12 months of age. This report is the first review of LS associated with WS.

Latent cerebral hypoperfusion in a boy with persistent nephrotic syndrome

Pediatricians are often faced with both bad temper and decreased daily activity in children with persistent nephrotic syndrome. These problems, which might affect both mental and physical development, have been explained as a consequence of general fatigue due to systemic edema and/or long-term hospitalization. However, other factors, such as cerebral hypoperfusion, may be involved. We experienced a case of a boy with steroid-resistant nephrotic syndrome who showed diffuse cerebral hypoperfusion on single photon emission computed tomography. Diffuse cerebral hypoperfusion dramatically resolved as the nephrotic syndrome remitted. His bad temper, decreased daily activity, and delay of speech and motor development also improved. In our patient, cerebral hypoperfusion might have been associated with his mental problems, physical problems, and delayed development of speech.