✓ The pathophysiology of primary arachnoid cysts of the middle cranial fossa is still unclear, and no widely accepted therapeutic criteria for this condition have been established. The authors present the case of a 7-year-old boy with this cyst accompanied by temporal lobe hypoplasia. On the basis of computerized tomography taken on the 2nd day after birth and magnetic resonance imaging upon admission, the arachnoid cyst in this case was attributed to brain hypoplasia secondary to abnormal arachnoid development and was confirmed to have developed primarily during infancy. Experience with this case yielded new findings useful in clarifying the pathophysiology of this condition and establishing therapeutic criteria for such a case.
Yoshinari Okumura, Toshisuke Sakaki and Hidehiro Hirabayashi
Kenji Fukutome, Yoshihiro Kuga, Hideyuki Ohnishi, Hidehiro Hirabayashi and Hiroyuki Nakase
Magnetic resonance imaging–guided focused ultrasound (MRgFUS) is a novel and useful treatment for essential tremor (ET); however, the factors impacting treatment outcome are unknown. The authors conducted this study to determine the factors affecting the outcome of MRgFUS.
From May 2016 through August 2017, 15 patients with ET were admitted to Ohnishi Neurological Center and treated with MRgFUS. To determine the factors impacting treatment outcome, the authors retrospectively studied correlations between the Clinical Rating Scale for Tremor (CRST) improvement rate and age, disease duration, baseline CRST score, skull density ratio (SDR), skull volume, maximum delivered energy, or maximum temperature.
The mean CRST score was 18.5 ± 5.8 at baseline and 4.6 ± 5.7 at 1 year. The rate of improvement in the CRST score was 80% ± 22%. Younger age and lower baseline CRST score were correlated with a higher CRST improvement rate (p = 0.025 and 0.007, respectively). To obtain a CRST improvement rate ≥ 50%, a maximum temperature ≥ 55°C was necessary. There was no correlation between SDR and CRST improvement rate (p = 0.658). A lower SDR and higher skull volume required significantly higher maximum delivered energy (p = 0.014 and 0.016, respectively). A higher maximum temperature was associated with a significantly larger lesion volume (p = 0.026).
Younger age and lower baseline CRST score were favorable outcome factors. It is important to assess predictive factors when applying MRgFUS.
Marissa D’Souza, Kevin S. Chen, Jarrett Rosenberg, W. Jeffrey Elias, Howard M. Eisenberg, Ryder Gwinn, Takaomi Taira, Jin Woo Chang, Nir Lipsman, Vibhor Krishna, Keiji Igase, Kazumichi Yamada, Haruhiko Kishima, Rees Cosgrove, Jordi Rumià, Michael G. Kaplitt, Hidehiro Hirabayashi, Dipankar Nandi, Jaimie M. Henderson, Kim Butts Pauly, Mor Dayan, Casey H. Halpern and Pejman Ghanouni
Skull density ratio (SDR) assesses the transparency of the skull to ultrasound. Magnetic resonance–guided focused ultrasound (MRgFUS) thalamotomy in essential tremor (ET) patients with a lower SDR may be less effective, and the risk for complications may be increased. To address these questions, the authors analyzed clinical outcomes of MRgFUS thalamotomy based on SDRs.
In 189 patients, 3 outcomes were correlated with SDRs. Efficacy was based on improvement in Clinical Rating Scale for Tremor (CRST) scores 1 year after MRgFUS. Procedural efficiency was determined by the ease of achieving a peak voxel temperature of 54°C. Safety was based on the rate of the most severe procedure-related adverse event. SDRs were categorized at thresholds of 0.45 and 0.40, selected based on published criteria.
Of 189 patients, 53 (28%) had an SDR < 0.45 and 20 (11%) had an SDR < 0.40. There was no significant difference in improvement in CRST scores between those with an SDR ≥ 0.45 (58% ± 24%), 0.40 ≤ SDR < 0.45 (i.e., SDR ≥ 0.40 but < 0.45) (63% ± 27%), and SDR < 0.40 (49% ± 28%; p = 0.0744). Target temperature was achieved more often in those with an SDR ≥ 0.45 (p < 0.001). Rates of adverse events were lower in the groups with an SDR < 0.45 (p = 0.013), with no severe adverse events in these groups.
MRgFUS treatment of ET can be effectively and safely performed in patients with an SDR < 0.45 and an SDR < 0.40, although the procedure is more efficient when SDR ≥ 0.45.