Does long segment subarachnoido-subarachnoid shunt prevent posttraumatic and postinfectious spinal arachnoid cyst recurrence?: technical note and case series.

Syringomyelia associated with extensive spinal adhesive arachnoiditis (SAA) can be defined as a rare but progressive disease with potentially devastating clinical consequences. Diagnosis can be challenging due to the absence of specific clinical findings, confusion with other pathologies, and late imaging modalities. The treatment strategy for syringomyelia associated with extensive SAA should include direct drainage of the syringomyelia, and dissection of the adhesive arachnoid with expansive duraplasty. Hence, several approaches have been reported for arachnoid dissection and decompression of the subarachnoid space. The high risk of recurrence after the operation is one of the most challenging situations. First two cases were operated previously, and the cyst walls were removed and anastomosed to the intact subarachnoid space at the upper and lower ends by each other. However, in both cases, the cyst recurred after a short time and they were anastomosed again in our clinic. A subarachnoid-subarachnoid shunt was placed with a multi-hole silicone tube extending to the proximal and distal intact subarachnoid spaces and passing through the cyst removal area. In our third case, the shunt system we described was applied directly, and satisfactory results were obtained in the clinical follow-up of the patient. It has been demonstrated that subarachnoido-subarachnoid shunt is a very satisfactory treatment option for this type of pathology, which is difficult to follow and treat.

Intracranial Arachnoiditis and Hydrocephalus.

A 62-year-old man presented a diffuse and predominantly cisternal acute nonaneurysmal subarachnoid hemorrhage associated with hydrocephalus. An external ventricular drain was placed, followed by clinical deterioration after its removal. At this point, a heavily T2-weighted high-resolution sequence of a brain magnetic resonance imaging showed acute hydrocephalus recrudescence and multiple arachnoid adhesions in the supravermian and interpeduncular cisterns, creating a loculated/cystic appearance. The diagnosis of intracranial arachnoiditis was made. Intracranial arachnoiditis results from meningeal inflammation. Fibrosis and adhesions at the subarachnoid spaces may follow, restricting cerebrospinal fluid circulation, particularly at the cranial base. Hydrocephalus probably resulted from the combination of subarachnoid hemorrhage and extensive scaring at the basal cisterns, precluding transdural and transvenous cerebrospinal fluid efflux. Heavily T2-weighted high-resolution magnetic resonance imaging sequences allow an exquisite depiction of arachnoiditis, displaying obstructive cisternal membranes, and contribute to better etiologic assessment and management of hydrocephalus.

Giant intradural extramedullary spinal ependymoma, a rare arachnoiditis-mimicking condition: case report and literature review.

BACKGROUND AND IMPORTANCE: Ependymomas are tumours arising from the ependymal cells lining the ventricles and the central canal of the spinal cord. They represent the most common intramedullary spinal cord tumour in adults and are very rarely encountered in an extramedullary location. Only 40 cases of intradural extramedullary (IDEM) ependymomas have been reported, all of which were diagnosed pre-operatively as IDEM ependymomas on contrast-enhanced MRI. CLINICAL PRESENTATION: We report a 23-year old male presenting with rapidly worsening signs and symptoms of spinal cord disease. A spinal MRI demonstrated a posterior multi-cystic dilatation extended between T1 and T12. Post-contrast sequences showed peri-medullar leptomeningeal enhancement and the diagnosis of spinal arachnoiditis was made. The patient underwent surgery and the spinal cord appeared circumferentially wrapped by an irregular soft tissue. The tissue was sub-totally removed and the pathological diagnosis was ependymoma WHO grade II. The patient experienced an excellent neurological recovery and no further treatments were administered. A small residue is now stable at 2.5 years follow-up. CONCLUSIONS: Giant IDEM ependymomas are rare entities and pre-operative diagnosis can be challenging in some cases. Surgery represents the main treatment option being resolutive in most cases.

MRI characteristics of syringomyelia associated with foramen magnum arachnoiditis: differentiation from Chiari malformation.

BACKGROUND: It is important to distinguish foramen magnum arachnoiditis (FMA) from Chiari malformation (CM) before surgery because the operative strategies for these diseases differ. In the current study, we compared pretreatment magnetic resonance imaging (MRI) of FMA with CM and investigated the MRI findings useful to differentiate between these diseases. METHODS: We retrospectively reviewed patients with FMA or CM aged ≥ 18 years who underwent surgeries at our institution between 2007 and 2019. The morphologies of the syrinx, neural elements, and posterior cranial fossa were preoperatively evaluated with MRI. We used the receiver operating characteristic (ROC) curve for the fourth ventricle-to-syrinx distance (FVSD). RESULTS: Ten patients with FMAs and 179 with CMs were included. FVSD in the FMA group was significantly shorter than that in the CM group (7.5 mm [IQR, 2.8-10 mm] in FMA vs. 29.9 mm [IQR, 16.3-52.9 mm] in CM, p < 0.0001). The other MRI findings that showed the height, size, and length of the syrinx; size of the foramen magnum; degree of cerebellar tonsillar descent; shape of the cerebellar tonsil; and dorsal subarachnoid space at the foramen magnum differed significantly between the two groups. The ROC curve analysis showed that patients whose FVSD was less than 11 mm could be diagnosed with FMA with a specificity of 90% and sensitivity of 96%. CONCLUSIONS: A more cranial syrinx development (FVSD < 11 mm) appears to be the characteristic MRI finding in FMA.

Reintervention rate of arachnolysis versus shunting for nonforaminal syringomyelia.

OBJECTIVE: Surgical treatment for nonforaminal syringomyelia related to spinal arachnoiditis is still controversial. The authors sought to assess respective outcomes and rates of reintervention for shunting and spinal cord untethering (arachnolysis) in spinal arachnoiditis with syringomyelia. METHODS: This retrospective cohort study was conducted at a single reference center for syringomyelia. Patients undergoing arachnolysis and/or shunting interventions for nonforaminal syringomyelia were screened. RESULTS: The study included 75 patients undergoing 130 interventions. Arachnolysis without shunting was performed in 48 patients, while 27 patients underwent shunting. The mean follow-up between the first surgery and the last outpatient visit was 65.0 months (range 12-379 months, median 53 months). At the last follow-up, the modified McCormick score was improved or stabilized in 83.4% of patients after arachnolysis versus 66.7% after shunting. Thirty-one (41.3%) patients underwent reintervention during follow-up, with a mean delay of 33.2 months. The rate of reintervention was 29.2% in the arachnolysis group versus 63.0% in the shunting group (chi-square = 8.1, p = 0.007). However, this difference was largely driven by the extension of the arachnoiditis: in patients with focal arachnoiditis (≤ 2 spinal segments), the reintervention rate was 21.6% for arachnolysis versus 57.1% for shunting; in patients with extensive arachnoiditis, it was 54.5% versus 65.0%, respectively. Survival analysis assessing the time to the first reintervention demonstrated a better outcome in both the arachnolysis (p = 0.03) and the focal arachnoiditis (p = 0.04) groups. CONCLUSIONS: Arachnolysis led to fewer reinterventions than shunting in patients with nonforaminal syringomyelia. There was a high risk of reintervention for patients with extensive arachnopathies, irrespective of the surgical technique.

Spinal Syrinx Due to Lipiodol-Induced Arachnoiditis.

We present a case of a progressive symptomatic intramedullary cyst, diagnosed decades after Lipiodol injection. Lipiodol was originally administered intrathecally for the radiologic diagnosis of spinal masses. A link between the lesion and the history of Lipiodol injection was never suspected. Surgical exploration revealed a membrane above the lesion, separating the intradural space in a cranial and caudal compartment. On the level of the cyst, we identified glassy pearls containing a fatty liquid, compatible with Lipiodol deposits. We hypothesize that the syrinx is secondary to the impact of cerebrospinal fluid pulsations on the reactive membrane and that this membrane originated from an arachnoiditis caused by Lipiodol deposits. Lipiodol was indeed abandoned after it was found to cause arachnoiditis and neurologic sequelae. Despite the cessation of its usage, the causal role of Lipiodol in arachnoiditis and spinal cyst formation should still be considered, as symptoms may arise many years after Lipiodol administration.

Hemifacial Spasm Secondary to Arachnoiditis Due to Neurocysticercosis: Clinical Image.

Subarachnoid neurocysticercosis (NCC) is a form of NCC with cysticerci located in the subarachnoid space. This form of NCC can cause general and focal neurologic symptoms, and sometimes requires surgical intervention as a treatment. In this report, we present a rare case of hemifacial spasm secondary to arachnoiditis because of an NCC cyst in the cerebellopontine angle. The cysticercus was removed and the facial nerve was liberated via a retrosigmoidal approach. At 8-month follow-up, the patient reported no recurrence of symptoms. To our knowledge, this is the first case reported to surgically manage hemifacial spasm secondary to NCC arachnoiditis.

Recurrent arachnoid cysts secondary to spinal adhesive arachnoiditis successfully treated with a ventriculoperitoneal shunt.

Spinal adhesive arachnoiditis (SAA) with cyst formation secondary to infectious meningitis is a rare clinical entity. These cysts can compress the spinal cord and cause neurologic decline. We present a case of a patient who underwent resection for an intradural schwannoma which was complicated post-operatively by bacterial meningitis and development of several recurrent thoracic arachnoid cysts. After two separate thoracic decompressions with lysis of intradural adhesions, a permanent ventriculoperitoneal shunt (VPS) was eventually placed with complete recovery of his symptoms. Our review of the literature showed that CSF shunts have previously been successfully used to treat spinal fluid collections. Although there are many factors to consider when treating these patients, CSF diversion may be beneficial for similar SAA presentations in order to simultaneously treat and prevent recurrence of symptoms.

Endoscopic-Assisted Spinal Arachnoiditis Adhesiolysis and Placement of a Spinal Cysto-Subarachnoid Shunt.

BACKGROUND: Spinal arachnoiditis and associated arachnoid adhesions can cause debilitating neurological symptoms due to nerve root and spinal cord compression or tethering. Adhesiolysis using a microscopic approach has traditionally been used for this condition. This procedure has been further refined in recent years with the use of flexible endoscopes. CASE DESCRIPTION: We report the case of a patient with progressive thoracic myelopathy secondary to arachnoid adhesions associated with arachnoiditis. A minimally invasive technique of adhesiolysis and placement of a cysto-arachnoid shunt was performed with the assistance of a flexible endoscope. CONCLUSIONS: The present case report has highlighted the advantages of using a flexible endoscope to treat spinal arachnoiditis adhesiolysis and placement of a cysto-arachnoid shunt, including a smaller skin incision and extended visualization.

A rare cause of progressive neuropathy: Arachnoiditis ossificans.

Arachnoiditis ossificans (AO) is a rare type of chronic arachnoiditis characterized by the presence of calcification or ossification of the spinal arachnoid which is usually associated with progressive neurological deficits. It is usually followed by prior history of trauma, surgery, infection, or myelography. Magnetic resonance imaging and computed tomography are the characteristics that are helpful in the diagnosis of most cases. Prognosis and treatment depends on the site and clinical presentation of the patients. We present a case of a young female who presented with a long-standing history of neurological symptoms and a intradural lesion mimicking a tumor.

Spinal Arachnoiditis Ossificans: Report of Quadruple-Triggered Case.

BACKGROUND: Arachnoiditis ossificans (AO) is a rare condition often associated with previous spine surgery. Here we describe a unique case of a patient affected by ankylosing spondylitis (AS), presenting with progressive neurologic deterioration due to AO. We also review the literature on evaluation and management of patients suffering from AO. CASE DESCRIPTION: The 65-year-old patient had a history of previous spinal trauma and related thoracolumbar surgery. Magnetic resonance imaging revealed multiloculated intradural/extramedullary cysts on the posterior surface of the spinal cord at Th9-L1, with clustered nerve roots. Computed tomography, with 3-dimensional reconstruction, demonstrated a likely ossification of both the dura and arachnoid from Th9 to S1. Microsurgical debridement of scar tissue from previous surgery, drilling of posterior ossified plaques at Th11-Th12-L1, and marsupialization and drainage of arachnoid cysts at Th11-Th12 were performed. CONCLUSIONS: We submit that AS, spinal trauma, epidural hematoma, and related surgery may be synergistic and independent factors in the etiopathogenesis of AO. This should be considered in patients with AS and/or a history of spinal surgery who present neurologic worsening.

Surgical treatment of a thoracic ventral intradural arachnoid cyst associated with syringomyelia: case report.

The pathogenesis of thoracic ventral intradural spinal arachnoid cyst (ISAC) is unknown due to its extremely low incidence. In addition, its surgical treatment is complicated because of the ventral location, large craniocaudal extension, and frequent coexistence of syringomyelia. The optimal surgical strategy for thoracic ventral ISAC remains unclear and continues to be a matter of debate. In this report, the authors describe an extremely rare case presenting with a compressive thoracic ventral ISAC associated with syringomyelia that was successfully treated with a simple cyst-pleural shunt. The patient's medical history revealed bacterial spinal meningitis along with an extensive spinal epidural abscess, suggesting the incidence of extensive adhesive arachnoiditis (AA) to be a plausible cause for this pathology. Thoracic ventral ISAC reportedly occurs secondary to AA and is commonly associated with syringomyelia. Placement of a cyst-pleural shunt is an effective, safe, and uncomplicated surgical strategy, which can provide sufficient cyst drainage regardless of the coexistence of AA, and thus should be considered as primary surgical treatment. Syrinx drainage could be reserved for a later attempt in case the cyst-pleural shunt fails to reduce the extent of syringomyelia.

Postarachnoiditis Anterior Spinal Arachnoid Cyst Formation with Compressive Myelopathy: Report of 2 Cases.

BACKGROUND: Spinal cystic arachnoiditis is a rare complication of a subarachnoid haemorrhage or infectious meningitis. The inflammatory process leads to fibrosis, adhesions, and in severe cases cyst formation. Large arachnoid cysts are an uncommon cause of compressive myelopathy. The majority are located posterior of the spinal cord at the thoracic level. Anterior cyst formation is exceptional, especially at the cervical region. CASE DESCRIPTION: We present 2 cases of progressive myelopathy secondary to anterior arachnoid cyst formation. In a 54-year-old female a large anterior symptomatic thoracic cyst arose 4 years after rupture of a posterior inferior cerebellar artery aneurysm. The other 59-year-old-patient, however, developed an anterior cervical cyst only weeks after a varicella meningoencephalitis. Both female patients were treated with a decompressive laminectomy and wide fenestration of the cysts. Partial recovery was obtained in 1 patient, but there was no improvement in the other case. CONCLUSIONS: Spinal cystic arachnoiditis with anterior cyst formation is an extremely rare complication of subarachnoid haemorrhage and infectious meningitis but can cause severe neurologic deficits. Clinicians should be aware of this rare complication. Due to the risk of irreversible spinal cord injury, rapid surgical intervention is recommended in most cases.

Spinal adhesive arachnoiditis following the rupture of an Adamkiewicz aneurysm: Literature review and a case illustration.

BACKGROUND: The rupture of an isolated spinal aneurysm is an exceptional occurrence. It might be responsible for a spinal subarachnoid haemorrhage (SSAH) that in rare cases can be complicated by arachnoiditis. Among the former the adhesive type is the most severe leading to the formation of a cyst and/or a syrinx. PATIENTS AND METHODS: The literature review was performed via a PubMed search using the following keywords. Adhesive arachnoiditis; spinal subarachnoid haemorrhage; spinal arachnoiditis; spinal arachnoid cyst; arachnoid cyst .Thesearch yielded 24 articles. Given the fact that only a few studies had been reported on the subject, we decided to include all studies regarding adhesive arachnoiditis after SAH leading to a descriptive literature review. Furthermore, a case illustration of a 57 year old man harbouring this type of rare pathology is described. RESULTS: Twenty-four case reports were found regarding spinal adhesive arachnoiditis (SAA) following SSAH. Posterior cerebral circulation bleeding (66.7%) most often occurred followed by spinal (9.1%) and anterior cerebral circulation (9.1%) respectively. The mean time between the haemorrhage and the SAA onset was 10 months. A higher predominance of symptomatic thoracic SAA was found. Including the present case, 80% of patients had a laminectomy, 72% had a micro adhesiolysis, and 56% a shunt placement. Cervical and upper thoracic involvement appeared to have a better outcome. CONCLUSION: Although most authors suggested surgical treatment, the long-term outcome remains unclear. Early stage diagnosis and management of this rare and disabling pathology may lead to a better outcome. Larger co-operative studies remain essential to obtain a better understanding of such a rare and complex disease.

[Treatment of syringomyelia associated with adhesive arachnoiditis]. / Lechenie siringomielii, assotsiirovannoi s adgezivnym arakhnoiditom.

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.

Shunt tube placement for amelioration of cerebrospinal fluid flow obstruction caused by spinal cord subarachnoid fibrosis in dogs.

OBJECTIVE: To describe a novel technique for ameliorating cerebrospinal fluid flow obstruction secondary to pia-arachnoid fibrosis in dogs and report outcome. STUDY DESIGN: Descriptive report and retrospective case series. ANIMALS: Dogs with cerebrospinal fluid (CSF) flow obstruction (n = 7). METHODS: Medical records were searched for dogs that had a subarachnoid-subarachnoid shunt placed for treatment of CSF flow obstruction. Data collected included age, sex, breed, clinical signs and duration of signs prior to examination, neurologic status and localization prior to surgery, pre-surgical diagnostics, surgical technique, histopathology, postoperative neurologic examination, time to discharge from hospital, and outcome. RESULTS: All dogs were diagnosed at surgery with a fibrotic adhesion between the arachnoid and pia mater. A subarachnoid shunting tube was implanted to allow CSF flow across the lesion site. Five dogs showed improvement of clinical signs, 3 of which showed complete recovery and 2 of which showed improvement without resolution of all clinical signs. Two dogs showed no change at 7 and 24 months postoperatively. CONCLUSION: Bridging a region of pia-arachnoid fibrosis with a tube placed in the subarachnoid space can ameliorate or prevent progression of associated clinical signs.

Encasement of the Cauda Equina After Early Childhood Meningitis: Case Report and Review of the Literature.

BACKGROUND: Arachnopathy following meningitis has been described in the setting of chronic spinal arachnoiditis and more recently as shunt-related progressive myelopathy due to meningeal thickening. CASE DESCRIPTION: We describe an atypical case of a patient who presented with chronic arachnopathy 5 decades after an episode of meningitis. We also review the literature concerning arachnopathies occurring in the context of early childhood meningitis. Although our case bore clinical and radiologic similarities to chronic spinal arachnoiditis and shunt-related progressive myelopathy, time to symptom onset, intraoperative findings, pathophysiology, and surgical outcome set it apart from both conditions. CONCLUSIONS: It is challenging but worthwhile to recognize this separate entity because, in contrast to both shunt-related progressive myelopathy due to meningeal thickening and adhesive arachnoiditis, surgery involving microsurgical dissection of the thick arachnoid encasement of the cauda equina may be curative in medically refractory cases.

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

Surgical lysis of the thickened arachnoid membrane is the first choice of treatment in spinal arachnoid pathologies that cause flow disturbances or blockage of CSF. However, it is important to consider that while extensive lysis of the arachnoid may temporarily provide a wide pathway for CSF, an extensive lytic procedure may later cause secondary adhesion. Thus, it is ideal for the proper extent of the arachnoid lysis to be determined after careful analysis of regional CSF flow. The authors report their limited experience with intraoperative visualization of CSF flow in spinal arachnoid pathologies. Two patients with a dorsal arachnoid web (DAW) with cervical syringomyelia and 1 patient with focal adhesive arachnoiditis causing edema of the spinal cord were surgically treated at the authors' institution between 2007 and 2013. In all cases, the presence of a DAW or focal adhesive arachnoiditis was suspected from the findings on MRI, namely 1) an indentation on the upper thoracic spinal cord and 2) syringomyelia and/or edema of the spinal cord above the indentation. Exploratory surgery disclosed a transversely thickened arachnoid septum on the dorsal side of the indented cord. To prove blockage of the CSF by the septum and to decide on the extent of arachnoid lysis, regional CSF flow around the arachnoid septum was visualized by subarachnoid injection of gentian violet solution close to the web. Injected dye stagnated just close to the arachnoid septum in all cases, and these findings documented CSF blockage by the septum. In 2 cases, a 2-minute observation showed that the injected dye stayed close to the web without diffusion. The authors performed not only resection of the web itself but also lysis of the thickened arachnoid on both sides of the spinal cord to make a CSF pathway on the ventral side. In the third case, the dye stagnated close to the web at first but then diffused through the nerve root to the ventral CSF space. The lysis procedure was completed after exclusive removal of the dorsal web. Postoperative MR images confirmed reduction of the syrinx and/or improvement of the edema in all cases, suggesting that the extent of arachnoid lysis was optimal in each case. No adverse effect was observed after subarachnoid injection of gentian violet. The authors believe that their technique of visualizing regional CSF flow will be helpful to decide the optimal extent of lysis in some local arachnoid pathologies.

Spinal arachnoid cyst associated with arachnoiditis following subarachnoid haemorrhage in adult patients: A case report and literature review.

OBJECTIVE: Arachnoiditis is an inflammatory process resulting with the fibrosis of arachnoid mater. It can vary in severity from mild thickenings to catastrophic adhesions that ruins subarachnoid space. As a result, arachnoid cysts can be formed. Arachnoid cyst induced by symptomatic spinal arachnoiditis is a rare complication of subarachnoid haemorrhages. In this article, we aimed to present a case of spinal arachnoid cyst formation following subarachnoid haemorrhage and examine similar cases in the literature. CASE REPORT: Forty-six years old, previously healthy female patient has been treated medically for headaches due to perimesencephalic subarachnoid bleeding. Approximately two and a half months later, she started to have severe headaches and diplopia. We detected hydrocephalus and performed ventriculoperitoneal shunt surgery. Two months later, she started to have complaints of weakness in her lower extremities. On neurological examination, she had paraparesis and on spinal magnetic resonance imaging she had an arachnoid cyst lengthening from C7 to T2 and compressing the spinal cord posteriorly. We performed partial laminectomy, drainage of arachnoid cyst and replacement of cystopleural T tube shunt. On follow-up, her lower extremity strength has ameliorated. She was taken into a physical therapy and rehabilitation programme. Three months later she was able to walk with a crutch. CONCLUSION: Subarachnoiditis and associated arachnoid cyst can cause severe morbidity. This rare situation (which especially occurs following subarachnoid haemorrhage of posterior fossa) should be known and physicians should keep in mind that it requires urgent surgical procedure.

Subarachnoid-subarachnoid bypass for spinal adhesive arachnoiditis.

The authors report a case of adhesive arachnoiditis (AA) and arachnoid cyst successfully treated by subarachnoid to subarachnoid bypass (S-S bypass). Arachnoid cysts or syringes sometimes compress the spinal cord and cause compressive myelopathy that requires surgical treatment. However, surgical treatment for AA is challenging. A 57-year-old woman developed leg pain and gait disturbance. A dorsal arachnoid cyst compressed the spinal cord at T7-9, the spinal cord was swollen, and a small syrinx was present at T9-10. An S-S bypass was performed from T6-7 to T11-12. The patient's gait disturbance resolved immediately after surgery. Two years later, a small arachnoid cyst developed. However, there was no neurological deterioration. The myelopathy associated with thoracic spinal AA, subarachnoid cyst, and syrinx improved after S-S bypass.