Visualization of regional cerebrospinal fluid flow with a dye injection technique in focal arachnoid pathologies

Experience Using Gentian Violet-Free Dyes for Tissue Visualization

BACKGROUND

 Gentian violet ink is used as a skin marker in various surgical procedures, including neurosurgery. The dye is also used to visualize the edges of blood vessels during bypass surgery. However, gentian violet ink carries the risks of carcinogenicity and venous injury, which causes microvascular thrombosis. In this study, we compare the gentian violet-free dye C.I. Basic Violet 4 (BV4) and gentian violet. The usefulness, in terms of color, and formation of microvascular thrombosis in anastomosis were compared.

METHODS

 We used the gentian violet-free dye in 20 cases involving 3 vascular anastomoses. The bone cutting lines on the bone surface, superior temporal artery, and middle cerebral artery were drawn using BV4 and gentian violet ink.

RESULTS

 The colors of BV4 and gentian violet ink were similar. No thrombus formation was observed at the vascular anastomosis when using BV4.

CONCLUSION

 BV4 can be used similarly to gentian violet ink. No adverse effects such as thrombus formation in microvascular anastomosis were experienced when BV4 was used.

Arachnoid webs with spinal cord compression: insights from three cases

Spinal arachnoid webs are intradural bands of abnormally formed arachnoid tissue, located within the subarachnoid space and causing compression of the dorsal aspect of the spinal cord. Arachnoid webs are uncommon and can be difficult to treat. We report 3 patients presenting with a spinal arachnoid web within a 6-month period. All of them exhibited signs of thoracic myelopathy and the MRI showed the pathognomonic 'scalpel sign'. Two of the patients underwent surgery for removal of their spinal arachnoid web, whereas the third patient case is currently being managed conservatively. We also present our 2D intraoperative video for arachnoid web removal and spinal cord decompression.

Surgical management of syringomyelia associated with spinal arachnoid web: strategies and outcomes

Spinal arachnoid web (SAW) is a rare disease entity characterized as band-like arachnoid tissue that can cause spinal cord compression and syringomyelia. This study aimed to analyze the surgical management of the spinal arachnoid web in patients with syringomyelia, focusing on surgical strategies and outcomes. A total of 135 patients with syringomyelia underwent surgery at our department between November 2003 and December 2022. All patients underwent magnetic resonance imaging (MRI), with a special syringomyelia protocol (including TrueFISP and CINE), and electrophysiology. Among these patients, we searched for patients with SAW with syringomyelia following careful analysis of neuroradiological data and surgical reports. The criteria for SAW were as follows: displacement of the spinal cord, disturbed but preserved CSF flow, and intraoperative arachnoid web. Patients were evaluated for initial symptoms, surgical strategies, and complications by reviewing surgical reports, patient documents, neuroradiological data, and follow-up data. Of the 135 patients, 3 (2.22%) fulfilled the SAW criteria. The mean patient age was 51.67 ± 8.33 years. Two patients were male, and one was female. The affected levels were T2/3, T6, and T8. Excision of the arachnoid web was performed in all cases. No significant change in intraoperative monitoring was noted. Postoperatively, none of the patients presented new neurological symptoms. The MRI 3 months after surgery revealed that the syringomyelia improved in all cases, and caliber variation of the spinal cord could not be detected anymore. All clinical symptoms improved. In summary, SAW can be safely treated by surgery. Even though syringomyelia usually improves on MRI and symptoms also improve, residual symptoms might be observed. We advocate for clear criteria for the diagnosis of SAW and a standardized diagnostic (MRI including TrueFISP and CINE).

Spinal arachnoid webs in adults: Clinical and imaging features in a multicenter study

BACKGROUND AND PURPOSE

Spinal arachnoid webs (SAWs) are rare and can present with myelopathic symptoms. This study aims to add 85 more cases of SAWs to the literature so we can continue to analyze clinical and imaging trends of SAWs to better understand this entity and its natural history.

METHODS

An institutional review board-approved retrospective review of SAW cases between 2016 and 2022 within a metropolitan, multihospital network was performed, searching for MR and CT reports that included "arachnoid web." Of 108 identified reports, 85 patients had imaging and/or pathologically proven arachnoid webs. Demographic and clinical data were collected. Images were analyzed for SAW level, point of maximum kyphosis, presence of cord expansion, and signal intensity. The electronic medical record (EMR) was reviewed for age, sex, symptom presentation and duration, management, and outcomes.

RESULTS

Of 85 cases, the most common presenting chief complaint was back pain and weakness. All (100%) SAWs were in the dorsal thoracic subarachnoid space, with 87% (74/85) located from thoracic (T) 2 to T6. Spinal cord expansion and signal abnormality were present in 54.1% and 23.5%, respectively. Twenty-six underwent surgical resection with 20 showing improvement of at least one symptom.

CONCLUSION

We present 85 additional cases of SAWs to the existing literature. Our cases all occurred in the dorsal thoracic subarachnoid space, predominantly from T2 to T6. Patients present with symptoms like other causes of cord compression, and spinal MR studies should be evaluated routinely for the findings of SAWs. Further research could focus on understanding SAW prevalence, risk factors, and pathophysiology.

The leptomeninges as a critical organ for normal CNS development and function: First patient and public involved systematic review of arachnoiditis (chronic meningitis)

BACKGROUND & IMPORTANCE

This patient and public-involved systematic review originally focused on arachnoiditis, a supposedly rare "iatrogenic chronic meningitis" causing permanent neurologic damage and intractable pain. We sought to prove disease existence, causation, symptoms, and inform future directions. After 63 terms for the same pathology were found, the study was renamed Diseases of the Leptomeninges (DLMs). We present results that nullify traditional clinical thinking about DLMs, answer study questions, and create a unified path forward.

METHODS

The prospective PRISMA protocol is published at Arcsology.org. We used four platforms, 10 sources, extraction software, and critical review with ≥2 researchers at each phase. All human sources to 12/6/2020 were eligible for qualitative synthesis utilizing R. Weekly updates since cutoff strengthen conclusions.

RESULTS

Included were 887/14286 sources containing 12721 DLMs patients. Pathology involves the subarachnoid space (SAS) and pia. DLMs occurred in all countries as a contributor to the top 10 causes of disability-adjusted life years lost, with communicable diseases (CDs) predominating. In the USA, the ratio of CDs to iatrogenic causes is 2.4:1, contradicting arachnoiditis literature. Spinal fusion surgery comprised 54.7% of the iatrogenic category, with rhBMP-2 resulting in 2.4x more DLMs than no use (p<0.0001). Spinal injections and neuraxial anesthesia procedures cause 1.1%, and 0.2% permanent DLMs, respectively. Syringomyelia, hydrocephalus, and arachnoid cysts are complications caused by blocked CSF flow. CNS neuron death occurs due to insufficient arterial supply from compromised vasculature and nerves traversing the SAS. Contrast MRI is currently the diagnostic test of choice. Lack of radiologist recognition is problematic.

DISCUSSION & CONCLUSION

DLMs are common. The LM clinically functions as an organ with critical CNS-sustaining roles involving the SAS-pia structure, enclosed cells, lymphatics, and biologic pathways. Cases involve all specialties. Causes are numerous, symptoms predictable, and outcomes dependent on time to treatment and extent of residual SAS damage. An international disease classification and possible treatment trials are proposed.

Evaluation of Ethyl Violet as an Alternative Dye to Crystal Violet to Visualize the Vessel Wall during Vascular Anastomosis

Crystal violet (CV) ink has been used as a skin marker worldwide. It has been reported to be useful for vessel wall visualization of microvascular anastomoses. Contrastingly, it has been found to be carcinogenic and inhibit migration and proliferation of venous cells. In some countries, its use in the medical field has been restricted. Therefore, it is necessary to consider alternatives to CV. In this present study, we compared the time required for the anastomosis of a 0.8-1 mm diameter vessel in the chicken wrist artery using CV and a CV-free dye (ethyl violet; EV). The surgeon, microscope, and anastomosis microsurgical tools were standardized for comparison. CV and EV were changed for each anastomosis. The same surgeon performed 30 anastomoses using each dye. No visually obvious differences were noted in the vascular transections with CV and EV. As per the results, no statistically significant difference was observed in the time required for anastomosis using CV and EV. EV conforming to California Proposition 65 may be an effective alternative to CV for vascular visualization of microvascular anastomoses. However, further studies on the effectiveness of the EV in clinical cases are needed.

Clinical Characteristics, Outcomes, and Pathology Analysis in Patients With Dorsal Arachnoid Web

BACKGROUND

Dorsal arachnoid webs (DAWs) are rare pathological abnormalities of the arachnoid layer of the spinal cord that can result in pain and myelopathy.

OBJECTIVE

To present clinical, imaging, and pathological characteristics of patients diagnosed with DAW, case illustrations, and a review of the literature.

METHODS

Seventeen cases of DAW between 2015 and 2019 at a tertiary medical center were retrospectively identified through a case log search. Patient characteristics, preoperative imaging, operative notes, and pathology reports were collected. Our main outcome assessed was postoperative resolution of symptoms. Odds ratios were used to determine associations between preoperative signs and symptoms with postoperative symptom resolution.

RESULTS

The mean age of the cohort was 50.5 years (IQR = 16) and presented primarily with back pain (64.7%). On imaging, all patients were found to have the "scalpel sign," and nearly half had a syrinx present (41.2%). All DAWs were located in the thoracic spine, with the most common location being the midthoracic (70.6%). The mean follow-up length for all patients was 4.3 months. There were no preoperative symptoms significantly associated with postoperative symptom resolution; however, a trend was noted with the presence of a preoperative syrinx. Pathology samples consistently demonstrated fibroconnective or collagenous tissue with no evidence of inflammation or neoplasm.

CONCLUSION

DAW is a rare pathology that can result in myelopathy or inappropriate interventions if misdiagnosed. Surgical intervention using laminectomy with intradural exploration should be considered in symptomatic patients with DAW because it is curative with a strong chance of preoperative symptom resolution with relatively low complication rates.

Multi-modality imaging evaluation of the dorsal arachnoid web

PURPOSE

Dorsal arachnoid web (DAW) is a rare intradural abnormality which is associated with progressive myelopathy. Our objective was to review multi-modality imaging techniques demonstrating the scalpel sign appearance in evaluation of DAW.

METHODS

We retrospectively reviewed various imaging modalities of patients found to have DAW at our institution during January 2015 to February 2020. Five patients underwent surgical decompression with pathological correlation. The remaining patients were presumptively diagnosed based on the characteristic finding of scalpel sign. Clinical data were evaluated and correlated to imaging findings. All imaging modalities demonstrated the characteristic scalpel sign.

RESULTS

Sixteen patients (10 females, and six males) with multi-imaging modalities were evaluated. Their mean age was 52 year (range 23-74 years). Fifteen patients underwent conventional spine MRI. Further high-resolution MR imaging techniques, e.g. 3D T2 myelographic sequence, were utilized with two patients. MRI spine CSF flow study was performed to evaluate the flow dynamic across the arachnoid web in one patient. Eight patients were evaluated with CT myelogram. Syrinx formation was discovered in seven (44%) patients; five (71%) of them underwent surgical resection and decompression. Two patients underwent successful catheter-directed fenestration of the web with clinical improvement. We found a statically significant positive correlation between the degree of cord displacement and compression with syrinx formation (r = 0.55 and 0.65 with p-value of 0.03 and 0.009, respectively).

CONCLUSION

DAW has characteristic scalpel sign independent of imaging modality. Multi-modality imaging evaluation of DAW is helpful for evaluation and surgical planning.

Rare dorsal thoracic arachnoid web mimics spinal cord herniation on imaging

Background:

Dorsal arachnoid webs (DAWs) are rare clinical entities that can mimic other conditions on magnetic resonance imaging (MRI). Here, we present a case of DAW that was misdiagnosed on MR as a ventral cord herniation.

Case Description:

A 35-year-old female presented with a 1-year history of lower extremity weakness and numbness. The MRI of the thoracic spine showed ventral cord displacement with syringomyelia. The computed tomography myelogram demonstrated ventral cord herniation. Intraoperatively, the patient had a dorsal thoracic web in the absence of cord herniation. Within 8 postoperative weeks, the patient had improved, and the follow-up MI showed a significant reduction in the syrinx size.

Conclusion:

On MR scans, DAWs may look like ventral cord herniation. However, the positive “scalpel sign” and syrinx, the absence of an arachnoid cyst on myelography, and the findings on cine MR help differentiate DAWs from ventral cord herniation.

Arachnoid web of the spine: a systematic literature review

OBJECTIVE

An arachnoid web of the spine (AWS) is a rare and oftentimes challenging lesion to diagnose, given its subtle radiographic findings. However, when left untreated, this lesion can have devastating effects on a patient's neurological function. To date, only limited case reports and series have been published on this topic. In this study, the authors sought to better describe this lesion, performing a systematic literature review and including 2 cases from their institution's experience.

METHODS

A systematic literature search was performed in September 2018 that queried Ovid MEDLINE (1946-2018), PubMed (1946-2018), Wiley Cochrane Library: Central Register of Controlled Trials (1898-2018), and Thompson Reuters Web of Science: Citation Index (1900-2018), per PRISMA guidelines. Inclusion criteria specified all studies and case reports of patients with an AWS in which any relevant surgery types were considered and applied. Studies on arachnoid cysts and nonhuman populations, and those that did not report patient treatments or outcomes were excluded from the focus review.

RESULTS

A total of 19 records and 2 patients treated by the senior authors were included in the systematic review, providing a total of 43 patients with AWS. The mean age was 52 years (range 28-77 years), and the majority of patients were male (72%, 31/43). A syrinx was present in 67% (29/43) of the cases. All AWSs were located in the thoracic spine, and all but 2 (95%) were located dorsally (1 ventrally and 1 circumferentially). Weakness was the most frequently reported symptom (67%, 29/43), followed by numbness and/or sensory loss (65%, 28/43). Symptoms predominated in the lower extremities (81%, 35/43). It was found that nearly half (47%, 20/43) of patients had been experiencing symptoms for 1 year or longer before surgical intervention was performed, and 35% (15/43) of reports stated that symptoms were progressive in nature. The most commonly used surgical technique was a laminectomy with intradural excision of the arachnoid web (86%, 36/42). Following surgery, 91% (39/43) of patients had reported improvement in their neurological symptoms. The mean follow-up was 9.2 months (range 0-51 months).

CONCLUSIONS

AWS of the spine can be a debilitating disease of the spine with no more than an indentation of the spinal cord found on advanced imaging studies. The authors found this lesion to be reported in twice as many males than females, to be associated with a syrinx more than two-thirds of the time, and to only have been reported in the thoracic spine; over 90% of patients experienced improvement in their neurological function following surgery.

Spinal arachnoid web-a review article

The spinal arachnoid web is an abnormal formation of an arachnoid membrane in the subarachnoid space. It is a rare entity with some degree of uncertainty surrounding its etiology. It can result in a displacement of the spinal cord causing pain and neurological symptoms as well as blockage of cerebrospinal fluid (CSF) flow and subsequent syringomyelia. The syrinx resulting from the altered CSF flow dynamics has been described to assume variable positions relative to the web itself. The "scalpel sign" is regarded as a pathognomonic feature of a spinal arachnoid web. The arachnoid web, however, is relatively thin and may be elusive of routine radiological investigations. As such, a myriad of preoperative and intraoperative investigations have been postulated to improve the sensitivity of detecting this abnormality. Management of spinal arachnoid webs ranges from conservative management to surgical excision where in the latter, the extent of excision remains the subject of debate. The authors herein present a review of the available information on this rare topic.

Microscope and Fiberscope-assisted Subarachnoid-Subarachnoid (S-S) Bypass: A Novel Surgical Technique to Reestablish Cerebrospinal Fluid Flow in Treating Dorsal Spinal Arachnoid Webs, Diagnosed by Cine-MRI

A "dorsal spinal arachnoid web" is the thickened arachnoid band on the surface of the spinal cord which disturbs the cerebrospinal fluid (CSF) flow, known as a rare cause of thoracic myelopathy. The ideal treatment is controversial because of the risk of readhesion after simple resection of the web. A subarachnoid-subarachnoid bypass is a method to reestablish CSF flow through a silicon tube between the cranial and caudal subarachnoid space. This method is reported to be useful for traumatic syringomyelia, adhesive arachnoiditis, etc. We applied this technique for arachnoid webs with the assistance of a microscope and fiberscope. After a dura incision, the thickened arachnoid web can be seen fluttering within the CSF flow inside the arachnoid space, which partitions the subarachnoid space into cranial and caudal parts. After opening the subarachnoid space and resection of the web under a microscope, the fiberscope is inserted toward the cranial and caudal directions to check for the presence of another arachnoid web. If another web is found, it is penetrated using a guiding wire. Then, a silicone tube is inserted into the cranial and caudal normal subarachnoid space. In this paper, we would like to introduce this technique.

Intraoperative Visualization of a Spinal Arachnoid Cyst Using Pyoktanin Blue

BACKGROUND

Spinal arachnoid cysts (SACs) are filled with cerebrospinal fluid, and they include the arachnoid membrane, making it difficult to distinguish the walls of the cyst from the arachnoid membrane and excise the cyst as a lump. Here we report a technique for the intraoperative visualization of SACs, involving the use of pyoktanin blue.

METHODS

Four patients with spinal intradural arachnoid cysts underwent total excision of the cysts between October 2016 and April 2017. In 1 case, magnetic resonance imaging revealed the cyst clearly, but in the other cases, the cysts were unclear. All cysts were injected with 1% pyoktanin blue (Wako Pure Chemical Industries, Osaka, Japan) diluted 500 times with physiological saline before excision. When it was difficult to distinguish the cyst from the normal arachnoid membrane, 1% pyoktanin blue diluted 1000 times with physiological saline was injected into both the cyst and the subarachnoid space, and the spread of the stain was observed.

RESULTS

The cysts were better visualized after pyoktanin blue injection than before injection. When it was difficult to distinguish the cyst from the normal arachnoid space, pyoktanin blue injection was useful for judging the cyst space. There were no perioperative complications, and the patients' symptoms improved partially or completely after treatment.

CONCLUSIONS

Our technique of pyoktanin blue injection into SACs could make their excision easy and safe.

[Treatment of syringomyelia associated with adhesive arachnoiditis]

The prevalence of syringomyelia (SM) caused by adhesive arachnoiditis (AA) is 2 to 4 cases per 100000 population. Surgical treatment of this pathology usually includes implantation of shunts into the cyst cavity or opening and drainage of the cavity. In this case, SM continues to progress in 72-100% of patients. Unsatisfactory outcomes of this surgical approach necessitate searching for other treatment options.

PURPOSE

To define the optimal amount of surgery for SM associated with AA and the criteria for assessment of surgery outcomes.

MATERIAL AND METHODS

The authors treated 47 SM patients in the period from 2010 to 2015. Of these, 34 (72.3%) patients underwent surgery; a total of 40 operations were performed. The patients' age ranged from 18 to 64 years (mean, 43.5 years). Tethering of the spinal cord was eliminated in 25 patients; 9 patients underwent cyst shunting.

RESULTS

Among operated patients, 5 patients had grade 1 arachnopathy, 13 patients had grade 2 arachnopathy, 12 patients had grade 3 arachnopathy, and 4 patients had grade 4 arachnopathy. The minimal postoperative follow-up period was 11 months. After shunting, the condition improved in 8 of 9 patients; in 7 patients, the condition returned to the baseline level within the first postoperative year; in 6 (66.7%) of these patients, the disease continued to progress. After surgical release of spinal cord tethering, satisfactory long-term results were achieved in 13 (86.6%) patients with grade 1-2 arachnopathy. In 3 (50%) patients with grade 3 arachnopathy, the condition was stabilized. Among patients with grade 4 arachnopathy, progression of the disease was stopped in 1 patient; the condition worsened in 2 (50%) patients. Among all the operated patients, complications developed in 7 patients. There were no lethal outcomes.

CONCLUSIONS

In grade 1-2 arachnopathy, progression of SM after release of spinal cord tethering occurs only in 13.4% of patients. Therefore, release of spinal cord tethering is recommended for these patients. In grade 3-4 arachnopathy, the rate of relapse after this surgery is more than 80%. Therefore, given the simplicity and a lower risk of complications of cyst shunting, this procedure is advisable for these patients.

Dorsal thoracic arachnoid web presenting as neuropathic pain: 'Scalpel' sign found on MRI

Dorsal thoracic arachnoid webs are due to a deformity in the formation of arachnoid membrane in the spinal arachnoid space. These webs usually occur in the upper thoracic spine and are viewed on imaging as a pathogonomic 'scalpel' sign because of the resemblance on sagittal MRI to a surgical scalpel. We describe a case of a patient with a neuropathic pain presentation. After MR imaging, a focal dorsal indentation of the upper thoracic spinal cord at the T3-T4 level with the scalpel sign was found. This sign indicates that the patient's neuropathic pain was caused by the dorsal thoracic arachnoid web.