[Surgical Techniques for Microvascular Decompression in Hemifacial Spasm].

This study discusses the key microvascular decompression(MVD)techniques for the treatment of hemifacial spasm(HFS). The author's experience is based on their institution's cases, highlighting three critical techniques. (1)Vertebral artery(VA)repositioning: Repositioning the VA is essential in challenging cases. This article focuses on the relocation of the proximal portion of the VA and the importance of careful dissection. (2)Relocating vessels compressing the peripheral branches of the facial nerve: HFS can result from nerve compression at various locations, including the cisternal portion. This study addressed cisternal compression and considered the nearby nerves. (3)Considering the perforating branches during repositioning, cases may involve complex branching of the perforating arteries. This paper describes an approach that carefully repositions the vessels without damaging the perforating branches. The results from 100 VA-involved cases showed excellent outcomes, with 91.2% of patients experiencing T0(excellent)results. This study emphasized the need to adapt the surgical approach to each unique case to ensure the safety and effectiveness of MVD. This study provides insights into the critical MVD techniques for HFS, emphasizing the importance of continuous experience and knowledge accumulation. These techniques can be learned by other neurosurgeons, thereby expanding the availability of safe and successful MVD procedures for HFS.

A Case of Septic Encephalopathy Diagnosed Following Non-inflammatory Febrile Response in an Elderly Patient After Sepsis.

Intracranial disorders are common in cases of prolonged disturbances of consciousness following sepsis. Among these, investigation of vascular lesions is warranted because only a few patients have encephalitic symptoms. However, the examination may not be comprehensive owing to the lack of rapid changes in the clinical status. This report presents the case of an elderly woman with severe sepsis who experienced prolonged disturbances in consciousness and persistent fever. Lumbar puncture results suggested the possibility of post-sepsis encephalitis. Sepsis induces systemic acute inflammation and activates autoimmune responses, leading to prolonged brain inflammation in some cases. When disturbances in consciousness persist after sepsis, a thorough investigation for the possibility of post-septic encephalitis is imperative.

A predicted CRISPR-mediated symbiosis between uncultivated archaea.

CRISPR-Cas systems defend prokaryotic cells from invasive DNA of viruses, plasmids and other mobile genetic elements. Here, we show using metagenomics, metatranscriptomics and single-cell genomics that CRISPR systems of widespread, uncultivated archaea can also target chromosomal DNA of archaeal episymbionts of the DPANN superphylum. Using meta-omics datasets from Crystal Geyser and Horonobe Underground Research Laboratory, we find that CRISPR spacers of the hosts Candidatus Altiarchaeum crystalense and Ca. A. horonobense, respectively, match putative essential genes in their episymbionts' genomes of the genus Ca. Huberiarchaeum and that some of these spacers are expressed in situ. Metabolic interaction modelling also reveals complementation between host-episymbiont systems, on the basis of which we propose that episymbionts are either parasitic or mutualistic depending on the genotype of the host. By expanding our analysis to 7,012 archaeal genomes, we suggest that CRISPR-Cas targeting of genomes associated with symbiotic archaea evolved independently in various archaeal lineages.

Objectively-captured Changes in Trigeminal Fibers before and after Microvascular Decompression Using 3D T2-SPACE MRI Might Relate to Eventual Residual Symptoms.

Although microvascular decompression (MVD) is a reliable treatment for trigeminal neuralgia (TN), neurosurgeons sometimes encounter patients whose symptoms do not improve postoperatively or who experience good treatment efficacy but develop other sensory disturbances. This study aims to objectively identify changes in nerve fibers before and after surgery by MRI and to clarify the relationship between the changes and residual postoperative symptoms. We retrospectively analyzed data from 36 consecutive patients who underwent MVD for classical TN at our hospital between November 2019 and November 2020. Cases that fulfilled the diagnostic criteria for multiple sclerosis were excluded. We confirmed the changes on the brainstem side of the trigeminal nerve preoperatively and at seven days postoperatively using 3D T2-SPACE MRI, in which the patients were divided into three groups: preoperative T2 high intensity positive (A), postoperative T2 high intensity positive (B), and no T2 high-intensity region (C). The primary outcome measures were therapeutic efficacy and frequency of postoperative numbness. The results of MVD surgery were evaluated one year postoperatively. The percentage of cases in which treatment outcomes were rated as excellent or good at one year: group A: 0 (0%), group B: 6 (100%), and group C: 25 (96.2%) (p < 0.05); the frequency of numbness: 2 (50%) in group A, 3 (50%) in group B, and 1 (3.8%) in group C, indicating significant differences between the three groups (p < 0.05). 3D T2-SPACE MRI sequences can be used to identify changes in trigeminal nerve fibers before and after MVD, which might correlate with eventual residual symptoms.

Long insular artery damage might be a key sign for predicting functional prognosis of putaminal hemorrhage.

OBJECTIVE: Although the putamen is the most common area of spontaneous intracerebral hemorrhage, previous reports about the effects of surgery are limited. We sometimes experience a poor prognosis in patients in whom there is no damage to the internal capsule, but with injury in the long insular artery (LIA) region. The purpose of this study was to confirm the relationship between LIA damage and patient prognosis following surgery for putaminal hemorrhage. METHODS: We retrospectively collected data of 287 surgical cases who presented with putaminal hemorrhage between January 2004 and March 2022. Among them, we chose patients without initial damage to the posterior limb of the internal capsule, and divided these patients into two groups, those without (Group A) and with (Group B) final damage in the LIA region. We compared positivity rates of final manual muscle test (MMT) scores≥3 and related factors. RESULTS: Sixty-three of the 287 patients were included in this study. Of them, 11 cases in Group A were positive for MMT scores≥3 (68.8%) and 9 cases (19.1%) in Group B had MMT scores≥3 seven days after surgery. Group A thus had a significantly higher rate of MMT scores≥3 than group B (p=0.00). CONCLUSION: In patients without initial damage to the internal capsule, LIA injury might be a key sign for predicting the functional prognosis of putaminal hemorrhage.

[A Case of Rhabdomyolysis Caused by Oxaliplatin during Postoperative Adjuvant Chemotherapy].

The patient was a 50-year-old male. At the age of 48 years, he had undergone total gastrectomy and right hemicolectomy simultaneously for gastric and ascending colon cancers. Since adjuvant chemotherapy has become common practice for patients with ascending colon cancer, capecitabine was administered for 6 months. One year and 6 months after the surgery, he was diagnosed with recurrence of the ascending colon cancer at the anastomotic site and underwent local colectomy. Considering he was pathologically diagnosed as pT4a, mFOLFOX6 therapy was prescribed as postoperative adjuvant chemotherapy. On the day the 11th course of treatment was initiated, the patient complained of weakness; however, his blood test results showed no abnormalities; therefore, he was followed-up as an outpatient. Three days later, he presented to the hospital with exacerbated symptoms and was diagnosed with rhabdomyolysis due to a marked increase in CK(2,031 U/L). Rhabdomyolysis was determined to be the adverse effect of oxaliplatin because out of all the drugs prescribed to the patient, this condition is listed as a side effect only in oxaliplatin's package insert. Fortunately, outpatient treatment was enough to alleviate rhabdomyolysis. Subsequently, adjuvant chemotherapy was completed without oxaliplatin. The patient has been followed-up without recurrence for 9 months after the surgery.

Significant Correlation between Structural Changes in the Net-like Appearance on Postoperative Cranial Magnetic Resonance Images and Hematoma Recurrence in Cases of Chronic Subdural Hematoma.

Organized hematoma, which exhibits a net-like appearance on imaging studies, is one of the predisposing factors for the recurrence of chronic subdural hematoma. Patients who are positive for the net-like appearance are often treated with only burr hole surgery. We investigated the relationship between postoperative structural changes in the net-like appearance and the recurrence rate of chronic subdural hematoma. Of the 949 patients with chronic subdural hematoma treated with primary burr hole surgery between January 2010 and April 2021 at our hospital, 268 who were considered positive for the net-like appearance on T2- and T2 star-weighted magnetic resonance images were extracted. We followed the structural changes in the net-like appearance postoperatively and subsequently classified the patients into three groups: decreasing type, shifting type, and no change and deterioration type. The relationship between each structural change and the recurrence rate in the three groups was investigated. Postoperative recurrence requiring surgery occurred in 3.5% of the subjects with decreasing type, 0% with shifting type, and 100% with deterioration type of the net-like appearance (P < 0.05), indicating differences in the recurrence rates according to postoperative structural changes in the magnetic resonance images (MRI) features of chronic subdural hematoma. Our results indicate that the risk of postoperative chronic subdural hematoma recurrence can be predicted by focusing on the structural changes in the postoperative net-like appearance on MRI.

Anaerobic methane-oxidizing activity in a deep underground borehole dominantly colonized by Ca. Methanoperedenaceae.

The family Ca. Methanoperedenaceae archaea mediates the anaerobic oxidation of methane (AOM) in different terrestrial environments. Using a newly developed high-pressure laboratory incubation system, we investigated 214- and 249-m deep groundwater samples at Horonobe Underground Research Laboratory, Japan, where the high and low abundances of Ca. Methanoperedenaceae archaea have been shown by genome-resolved metagenomics, respectively. The groundwater samples amended with 13 C-labelled methane and amorphous Fe(III) were incubated at a pressure of 1.6 MPa. After 3-7 days of incubation, the AOM rate was 45.8 ± 19.8 nM/day in 214-m groundwater. However, almost no activity was detected from 249-m groundwater. Based on the results from 16S rRNA gene analysis, the abundance of Ca. Methanoperedenaceae archaea was high in the 214-m deep groundwater sample, whereas Ca. Methanoperedenaceae archaea was undetected in the 249-m deep groundwater sample. These results support the in situ AOM activity of Ca. Methanoperedenaceae archaea in the 214-m deep subsurface borehole interval. Although the presence of Fe-bearing phyllosilicates was demonstrated in the 214-m deep groundwater, it needs to be determined whether Ca. Methanoperedenaceae archaea use the Fe-bearing phyllosilicates as in situ electron acceptors by high-pressure incubation amended with the Fe-bearing phyllosilicates.

Microvascular Decompression for Concurrent Trigeminal Neuralgia and Hemi-Laryngopharyngeal Spasm: A Case Report.

BACKGROUND AND IMPORTANCE: Hemi-laryngopharyngeal spasm (HeLPS) may result from vascular compression of the vagus nerve and can be treated using microvascular decompression. We describe the clinical characteristics and surgical treatment in a case of concurrent trigeminal neuralgia (TN) and HeLPS. CLINICAL PRESENTATION: A 44-year-old man presented with a 12-month history of right TN and 8-month history of intermittent episodes of repeated throat contractions associated with a very distressing choking sensation. Preoperative 3-dimensional fusion imaging demonstrated compression of the trigeminal nerve by the superior cerebellar artery and petrosal vein and compression of the vagus nerve by the posterior inferior cerebellar artery and one of its branches. Microvascular decompression was performed by a right standard retrosigmoid approach with enlarged craniotomy. Initially, the compression of the trigeminal nerve was identified by visual inspection. All the offending vessels were wrapped in Teflon felt, transposed away from the trigeminal nerve, and adhered to the tentorial membrane and petrous bone using fibrin glue. Furthermore, observation of the caudal rootlets of the vagus nerve revealed that the posterior inferior cerebellar artery and its branch compressed the ventral side of the nerve. These vessels were displaced antero-caudally with Teflon felt and fibrin glue; no other vessels were found around the trigeminal and vagus nerves. Postoperatively, the patient had immediate and complete resolution of symptoms of TN and HeLPS without recurrence at the 18-month follow-up. CONCLUSION: HeLPS may occur with TN, and neurosurgeons should identify the symptoms suspicious of this disease preoperatively.

Injectable extracellular matrix hydrogels contribute to native cell infiltration in a rat partial nephrectomy model.

Decellularized extracellular matrix (dECM) hydrogels have cytocompatibility, and are currently being investigated for application in soft tissues as a material that promotes native cell infiltration and tissue reconstruction. A dECM hydrogel has broad potential for application in organs with complex structures or various tissue injury models. In this study, we investigated the practical application of a dECM hydrogel by injecting a kidney-derived dECM hydrogel into a rat partial nephrectomy model. The prepared dECM hydrogel was adjustable in viscosity to allow holding at the excision site, and after gelation, had an elastic modulus similar to that of kidney tissue. In addition, the migration of renal epithelial cells and vascular endothelial cells embedded in dECM hydrogels was observed in vitro. Four weeks after injection of the dECM hydrogel to the partial excision site of the kidneys, infiltration of renal tubular constituent cells and native cells with high proliferative activity, as well as angiogenesis, were observed inside the injected areas. This study is the first to show that dECM hydrogels can be applied to the kidney, one of the most complex structural organs and that they can function as a scaffold to induce angiogenesis and infiltration of organ-specific renal tubular constituent cells, providing fundamental insights for further application of dECM hydrogels.

A widespread group of large plasmids in methanotrophic Methanoperedens archaea.

Anaerobic methanotrophic (ANME) archaea obtain energy from the breakdown of methane, yet their extrachromosomal genetic elements are little understood. Here we describe large plasmids associated with ANME archaea of the Methanoperedens genus in enrichment cultures and other natural anoxic environments. By manual curation we show that two of the plasmids are large (155,605 bp and 191,912 bp), circular, and may replicate bidirectionally. The plasmids occur in the same copy number as the main chromosome, and plasmid genes are actively transcribed. One of the plasmids encodes three tRNAs, ribosomal protein uL16 and elongation factor eEF2; these genes appear to be missing in the host Methanoperedens genome, suggesting an obligate interdependence between plasmid and host. Our work opens the way for the development of genetic vectors to shed light on the physiology and biochemistry of Methanoperedens, and potentially genetically edit them to enhance growth and accelerate methane oxidation rates.

Significant Correlation between Delayed Relief after Microvascular Decompression and Morphology of the Abnormal Muscle Response in Patients with Hemifacial Spasm.

Although microvascular decompression (MVD) is a reliable treatment for hemifacial spasm (HFS), postoperative delayed relief of persistent HFS is one of the main issues. In patients with hemifacial spasm, stimulation of a branch of the affected facial nerve elicits an abnormal response in the muscles innervated by another branch. Several specific types of waves were found in the abnormal muscle response (AMR). This study aimed to confirm the relationship between the initial morphology of the AMR wave and delayed relief of persistent HFS after MVD. We retrospectively analyzed and compared the data from 47 of 155 consecutive patients who underwent MVD for HFS at our hospital between January 2015 and March 2020. Based on the pattern of the initial AMR morphology on orbicularis oculi and mentalis muscle stimulation, patients were divided into two groups, namely, the monophasic and polyphasic groups. The results of MVD surgery for HFS were evaluated 1 week, 1 month, and 1 year postoperatively, by evaluating whether or not the symptoms of HFS persisted at the time of each follow-up. There were significantly higher rates of persistent postoperative HFS in patients with the polyphasic type of initial AMR at 1 week and 1 month after the surgery (p < 0.05, respectively), as assessed using Yates chi-squared test and Fisher's exact test. A significant correlation was observed between delayed relief after MVD and polyphasic morphology of the AMR in electromyographic analysis in patients with hemifacial spasm.

Intravenous Fosphenytoin Therapy as an Acute Rescue Treatment for Glossopharyngeal Neuralgia Crisis in Patients Awaiting Neurosurgical Procedures: A Case Series.

INTRODUCTION: Few treatments exist for acute attacks of glossopharyngeal neuralgia (GPN). We investigated the efficacy of intravenous fosphenytoin therapy (IFT) during GPN crisis. CASE PRESENTATION: We evaluated records of 4 consecutive patients with GPN awaiting microvascular decompression (MVD) who received IFT (total, 750 mg). Pain severity was evaluated using a Numerical Rating Scale (NRS). The score was 10 (maximum pain) before treatment. Case 1 (a 52-year-old woman, left GPN): for 12 hours after IFT, pain was eliminated (NRS 0/10); however, severe pain recurred 2 days later. She received MVD 9 days after IFT. Case 2 (a 72-year-old woman, right GPN): pain score reduced to 0/10 immediately after IFT and remained so for 2 days. Severe pain recurred, and she underwent MVD 4 days after IFT. Case 3 (a 69-year-old woman, right GPN): pain was reduced (NRS, 5/10) immediately after IFT and nearly eliminated (1/10) 1 hour later. After 6 hours, severe pain recurred; she received a second IFT 3 days later, and pain score dropped to 1/10. She was pain-free for 24 hours but intermediate pain recurred in 2 days. Microvascular decompression was performed 9 days after the second IFT. Case 4 (a 32-year-old woman, right GPN): Pain score reduced to 0/10 immediately after IFT and remained so for 4 days. She underwent MVD 4 days after IFT. No evidence of recurrence was found throughout the 24-, 22-, 20-, and 5-month follow-ups. CONCLUSIONS: These results provide new insights into the innovative therapeutic option of intravenous fosphenytoin and contribute to advancements in treating acute GPN crisis.

Lateral Supracerebellar Infratentorial Approach for Superior Oblique Myokymia: A Case Series.

BACKGROUND: Few reports have shown that superior oblique myokymia (SOM) may result from vascular compression of the trochlear nerve and may be curable using microvascular decompression (MVD). OBJECTIVE: To report the clinical characteristics and surgical treatment of 2 cases of SOM and provide a review of the related literature. METHODS: Two patients with SOM were treated using MVD with the lateral supracerebellar infratentorial approach. The patients underwent diagnostic magnetic resonance imaging and three-dimensional fusion imaging preoperatively. A lateral suboccipital craniotomy was performed in the park-bench position. The trochlear nerve and branches of the superior cerebellar artery were confirmed after opening the cerebellomesencephalic fissure over the tentorial surface of the cerebellum. The vessel, which compressed the root exit zone of the trochlear nerve, was transposed far from the nerve and attached to the surface of the midbrain using Teflon felt and fibrin glue. RESULTS: The first case showed compression on both the ventral and rostral sides of the trochlear nerve root exit zone, and the second showed compression only on the ventral side. Large bridging veins on the tentorial surface of the cerebellum complicated the approach in the second case. Postoperatively, both patients had immediate and complete resolution of symptoms without recurrence at the 24-mo and 17-mo follow-ups, respectively. Five previous reports described the complete resolution of SOM after MVD. CONCLUSION: A presentation of an intermittent fluttering ocular sensation should prompt magnetic resonance imaging for ipsilateral trochlear nerve compression. The lateral supracerebellar infratentorial approach allows safe and efficacious MVD for SOM.

Cisplatin-Chelated Iminodiacetic Acid-Conjugated Hyaluronic Acid Nanogels for the Treatment of Malignant Pleural Mesothelioma in Mice.

Malignant pleural mesothelioma (MPM) is one of the intractable cancers that require a more effective therapeutic strategy for clinical practice. Hyaluronic acid (HA) nanogels were prepared by the chelation of cisplatin (CDDP) with different molecular weights of iminodiacetic acid-conjugated hyaluronic acid (HA-IDA). The sizes of the 100, 850, and 2000 kDa HA nanogels were 33, 43, and 44 nm, respectively. MSTO-211H, a human MPM cell line, was more effective in taking up all three HA nanogels compared to AB22, a mouse MPM cell line. In addition, the 850 kDa HA nanogel showed higher anticancer activity against AB22 and MSTO-211H than 100 and 2000 kDa HA nanogels. Furthermore, all the HA nanogels showed a milder cytotoxic effect on normal Met-5A mesothelial cells compared to that exhibited by free CDDP. Finally, the 850 kDa HA nanogel was administrated intrapleurally into both the MSTO-211H xenograft and AB22 allograft mouse models of MPM using an injectable HA-based hydrogel. HA nanogels showed a significant therapeutic effect in both the xenograft and allograft models.

Risk factors for root caries annual incidence and progression among older people requiring nursing care: A one-year prospective cohort study.

PURPOSE: We aimed to determine root caries annual incidence (RCAI) and root caries annual progression (RCAP) and risk factors for them among older people requiring nursing care. METHODS: The target population comprised 186 dentate individuals aged ≥ 65 years who required nursing care while living in nursing homes (NHs) or their own homes (OHs) in Okayama, Japan. Survey items included presence/absence and severity of root caries, age, sex, living environment (NH or OH), the Clinical Dementia Rating, and the Barthel Index (BI). Baseline surveys were conducted from 2015 to 2017; subjects were followed up for one year. RCAI and RCAP per tooth and per person were calculated, and risk factors for them were identified using generalized estimating equations. RESULTS: In total, 104 individuals (mean age: 82.0 ± 12.4 years) completed the follow-up survey. RCAIs per tooth and per person were 14.6% (173/1188) and 59.6% (62/104), respectively. RCAP per tooth was 22.5% (51/227 teeth with root caries at baseline). Significant risk factors for RCAI were living environment (OH, odds ratio [OR]: 2.14), sex (male, OR: 1.84), clasped tooth (OR: 1.82), and older age (OR: 1.05) at baseline. Significant risk factors for RCAP were sex (male, OR: 5.20), regular dental checkup (OR: 2.74), and high BI score (OR: 1.02) at baseline. CONCLUSION: At one-year follow-up, 59.6% of the subjects developed at least one root caries. Risk factors for RCAI were living environment (OH), male, clasped tooth, and older age, whereas those for RCAP were male, regular dental checkup, and high BI score.

[A Case of Extramural Growth-Type Ileocecal Colon Cancer].

A woman in her 80s was diagnosed with an abdominal mass during physical examination. Contrast-enhanced computed tomography(CT)revealed a tumor with contrast enhancement outside the ileocecal region of the intestine, and the ileocolic artery penetrated the tumor. No tumor was detected by colonoscopy. An endoscope could not be passed through due to an ileocecal valve stenosis. A biopsy of the ileocecal valve revealed only lymphocyte hyperplasia without adenocarcinoma components. Barium enema examination demonstrated no influx of the contrast medium from the cecum into the oral side of the intestine. Since a gastrointestinal stromal tumor in the ileocecal region was suspected, laparotomy was performed in the ileocecal region owing to the preoperative diagnosis of suspected malignant lymphoma, revealing a 5-cm elastic hard tumor outside the ileocecal wall. The tumor could not be separated from the intestinal tract. Histopathological examination revealed no lesion on the mucosal surface, although poorly differentiated adenocarcinoma infiltrated from the submucosa to the serosa. Thus, the patient was diagnosed with extramural growth-type ileocecal colon cancer. This disease is relatively rare but need to be kept in mind.

[A Case of Transverse Colon Cancer Complicated by Eosinophilic Granulomatosis with Polyangiitis].

A man in his 50s had undergone steroid therapy for eosinophilic granulomatosis with polyangiitis(EGPA). Since an examination for malignant tumors revealed type 0-Ⅰsp(cT1aN0M0)and type 2(cT2N0M0)lesions in the proximal and mid- transverse colon, respectively, he was referred to our department. Endoscopic resection was performed on the proximal lesion. After the confirmation of curative resection, laparoscopic partial colectomy(transverse colon)and D3 lymph node dissection were performed on the mid-transverse lesion. Because of the patient's favorable postoperative course, he was discharged from the hospital on POD17. Since steroids and immunosuppressants may cause immunological abnormalities and malignant tumors, such patients should be strictly followed up.

Intravenous fosphenytoin therapy for rescue of acute trigeminal neuralgia crisis in patients awaiting neurosurgical procedures: A cross-sectional study.

Few treatments exist for acute attacks of trigeminal neuralgia. Therefore, this study aimed to investigate the efficacy and safety of an intravenous fosphenytoin therapy protocol in a trigeminal neuralgia crisis. We conducted a single-center, retrospective, observational study of the records of 20 patients with trigeminal neuralgia who received intravenous fosphenytoin therapy (15 mg/mL in normal saline at 50 mg/min for 15 min, total 750 mg) during hospitalization between September 2015 and August 2020. Serum phenytoin concentration was measured 30 min post-infusion. Pain severity was evaluated using a numerical rating scale and was analyzed for statistical significance. The mean age of the patients was 67.5 years (female, 50.0%). The median numerical rating scale score (interquartile range) of pain severity was 2.35 (0-10), 0.65 (0-5), 0.15 (0-1), 2.00 (0-8), and 4.30 (0-10) at 15, 30, and 60 min, and 12 and 24 h, respectively (p < .001); the numerical rating scale score was 10 before treatment. Reduction in pain 24 h following treatment was significant. The mean phenytoin concentration was 12.8 µg/mL 30 min post-treatment. While mild dizziness occurred in four patients, all could walk independently within 60 min. The mean age and weight of patients with mild dizziness were significantly higher and lower, respectively (p < .001), than those of other patients. These results may provide physicians with new insights into the innovative therapeutic option of intravenous fosphenytoin and contribute to advancements in treating acute trigeminal neuralgia crisis.

Patterns of Gene Content and Co-occurrence Constrain the Evolutionary Path toward Animal Association in Candidate Phyla Radiation Bacteria.

Candidate Phyla Radiation (CPR) bacteria are small, likely episymbiotic organisms found across Earth's ecosystems. Despite their prevalence, the distribution of CPR lineages across habitats and the genomic signatures of transitions among these habitats remain unclear. Here, we expand the genome inventory for Absconditabacteria (SR1), Gracilibacteria, and Saccharibacteria (TM7), CPR bacteria known to occur in both animal-associated and environmental microbiomes, and investigate variation in gene content with habitat of origin. By overlaying phylogeny with habitat information, we show that bacteria from these three lineages have undergone multiple transitions from environmental habitats into animal microbiomes. Based on co-occurrence analyses of hundreds of metagenomes, we extend the prior suggestion that certain Saccharibacteria have broad bacterial host ranges and constrain possible host relationships for Absconditabacteria and Gracilibacteria. Full-proteome analyses show that animal-associated Saccharibacteria have smaller gene repertoires than their environmental counterparts and are enriched in numerous protein families, including those likely functioning in amino acid metabolism, phage defense, and detoxification of peroxide. In contrast, some freshwater Saccharibacteria encode a putative rhodopsin. For protein families exhibiting the clearest patterns of differential habitat distribution, we compared protein and species phylogenies to estimate the incidence of lateral gene transfer and genomic loss occurring over the species tree. These analyses suggest that habitat transitions were likely not accompanied by large transfer or loss events but rather were associated with continuous proteome remodeling. Thus, we speculate that CPR habitat transitions were driven largely by availability of suitable host taxa and were reinforced by acquisition and loss of some capacities. IMPORTANCE Studying the genetic differences between related microorganisms from different environment types can indicate factors associated with their movement among habitats. This is particularly interesting for bacteria from the Candidate Phyla Radiation because their minimal metabolic capabilities require associations with microbial hosts. We found that shifts of Absconditabacteria, Gracilibacteria, and Saccharibacteria between environmental ecosystems and mammalian mouths/guts probably did not involve major episodes of gene gain and loss; rather, gradual genomic change likely followed habitat migration. The results inform our understanding of how little-known microorganisms establish in the human microbiota where they may ultimately impact health.