The "subdural" space: a new look at an outdated concept

The role of exudation in chronic subdural hematomas

Object

Chronic subdural hematomas (SDHs) are a local inflammatory process that causes the formation of a granulation tissue often referred to as the external or outer membrane. This membrane has abnormally permeable macrocapillaries. Therefore, exudation from the macrocapillaries in the outer membrane of chronic SDH may play an important role in the enlargement of chronic SDH. In this study the authors investigated the role of exudation in chronic SDH.

Methods

The authors examined 24 patients (16 men and eight women; age range 38–86 years [mean age 61.4 years]) with 27 chronic SDHs. The clinical status of the patients was evaluated according to the classification described by Markwalder. The diagnosis was established on computed tomography (CT) scans in all cases. The authors also used the Nomura Classification for judging the lesion's appearance on CT scans. Immediately after the diagnosis, all patients were administered 20 mCi (740 mBq) technetium-99m human serum albumin. Four hours later, blood and SDH samples were taken and radioactivity levels were measured in each. The ratio of activity of the samples taken from chronic SDH to the radioactivity of blood was determined as a percentage and defined as the exudation rate. On the follow-up CT scan obtained on postoperative Day 20, subdural collections thicker than 5 mm were determined to be a reaccumulation.

Results

The correlations between the exudation rate and age of the patients, clinical grades, CT appearances, and amount of reaccumulation were investigated. In this series the average exudation rate was 13.24% (range 2.05–28.88%). The mean exudation rates according to the clinical grades assigned to patients were as follows: Grade 0, 8.67 ± 5.64% (three patients); Grade 1, 5.07 ± 1.43% (eight patients); Grade 2, 17.87 ± 3.73% (seven patients); and Grade 3, 19.65 ± 7.67% (six patients). Exudation rates in patients with Grades 2 and 3 were significantly higher than those in Grades 0 and 1 (p < 0.05).

The mean exudation rates according to the lesion's appearance on CT scans were found as follows: hypodense appearance, 6.55 ± 4.52% (eight patients); isodense appearance, 11.07 ± 6.32% (five patients); hyperdense appearance, 19.47 ± 13.61% (three patients); and mixed-density appearance, 17.40 ± 5.80% (nine patients). The differences among the groups were significant (p < 0.05). The average exudation rate was statistically higher in the patients with reaccumulation (16.30 ± 8.16%) than that in the patients without reaccumulation (9.96 ± 6.84%) (p < 0.05).

Conclusions

The exudation rate in chronic SDH is correlated with a higher clinical grade (Markwalder Grade 2 or 3), mixed-density CT appearance, and reaccumulation. Therefore, exudation from macrocapillaries in the outer membrane of chronic SDH probably plays an important role in the pathophysiology and the growth of chronic SDH.

[Acute non-traumatic extensive subdural spinal hematoma]

Acute spinal subdural hematoma is a somewhat rare pathology. Its severity comes from the constitution of an acute spinal cord compression. In many cases MRI is useful for the differential diagnosis with the epidural hematoma. A 79-year-old patient was referred for emergency neurosurgery for acute spinal cord compression. The vascular risk in this patient was significant: hypertension, oral anticoagulants. Clinically, acute non-traumatic subdural spinal hematoma was suspected. The spinal cord MRI was in favor of the diagnosis which was confirmed intraoperatively. The surgical procedure revealed an extensive hematoma which infiltrated the spinal cord. The diagnosis of nontraumatic subdural spinal hematoma may be difficult in some cases and correctly established only during the surgical procedure. In comparison with reports in the literature, we discuss the underlying mechanisms of this hematoma. Spinal subdural haematoma must be considered in patients taking anticoagulant therapy or with a coagulation disorder who present signs of acute spinal cord compression. MRI sagittal T1 and T2-weighted images are adequate and reliable for diagnosis of spinal subdural hematoma. Prompt surgical evacuation of this hematoma is crucial.

Complete failure of spinal anaesthesia in obstetrics

Intrathecal anaesthesia, either as a single shot-spinal or as part of a combined spinal-epidural technique, is now widely accepted as the management of choice for caesarean section. It generally produces rapid and predictable anaesthesia, yet occasionally fails for no apparent reason. Four case reports of seemingly inexplicable complete failure of intrathecal anaesthesia are presented, together with a literature review of other cases and possible causes of the failure, which include anatomical abnormality, drug failure and management failure.

Membranectomy in organized chronic subdural hematomas: indications and technical notes

BACKGROUND

The aim of the present study is to present our operative method of removing organized CSDHs and to structure the criteria for choosing this approach as first treatment.

METHODS

Between 1991 and 1999 at our Institution, 14 consecutive patients with organized CSDHs required 16 craniotomies with membranectomy. They represent 5.8% of all patients (243) treated for CSDHs in the same period. All the patients had preoperative contrast-enhanced CT, and 9 patients also had contrast MRI.

RESULTS

Initially, 9 patients underwent one burr hole or twist-drill hole. Of these 9 patients, 3 were treated at the same surgery with craniotomy and membranectomy as second treatment, 3 underwent a second burr hole and then membranectomy at the same surgery, and 3 patients underwent a second burr hole 3, 4, and 21 days after the first one and then membranectomy. Five patients underwent immediate craniotomy and membranectomy. There were no morbidity or mortality associated with this procedure. All patients had a full recovery without recurrence.

CONCLUSIONS

Contrast-enhanced MRI has greatly improved opportunities for discovering neomembrane before surgical intervention. We believe that MRI detection of thick and extensive membranes or solid clot with mass effect makes an immediate craniotomy to remove CSDH necessary.

Spinal Subdural Hematoma Following Intracranial Aneurysm Surgery-Four Case Reports-

Four patients presented with rare spinal subdural hematoma (SDH) occurring after intracranial aneurysm surgery and manifesting as postoperative back pain. Magnetic resonance imaging performed from 4 to 11 days after the operation showed acute or subacute thoracolumbar SDH. No patient had risk factors for bleeding at this site (e.g., lumbar puncture, coagulation abnormality). Overdrainage of the cerebrospinal fluid (CSF) was performed for brain retraction during the operation in all four cases. Computed tomography performed during the postoperative period showed a suspicious tentorial subdural hemorrhage in Case 1 and an interhemispheric subdural hemorrhage in Case 3. All four patients received conservative management and their lumbago improved. We hypothesize that CSF hypotension due to overdrainage of CSF and downward migration of intracranial SDH under the influence of gravity were involved in the formation of spinal SDH.

Paroxysmal coughing, subdural and retinal bleeding: a computer modelling approach

Unexplained subdural and retinal haemorrhages in an infant are commonly attributed to 'shaking', the mechanism of which is believed to be traumatic venous rupture. However, the haemorrhagic retinopathy reported as a result of Valsalva manoeuvres and the subdural bleeding that is a rare complication of pertussis together demonstrate that if a sustained rise in intrathoracic pressure is transmitted to cerebral and retinal vessels, it may result in bleeding, similar to that reported in inflicted injury. Such haemorrhages would be expected to occur whenever severe paroxysmal coughing were induced, whatever the cause. This study used a computer modelling approach to investigate feeding accidents as the trigger for bleeding. A dynamic circulatory model of a 3-month-old infant was induced to 'cough', and the response to changes in physiological variables monitored. It showed that coughing causes intracranial pressures to build up exponentially to approach a maximum, proportional to the amount of pressure the musculature of the thorax can produce, as venous return is impeded. They do not have time to become dangerous during individual coughs, as blood quickly returns after the cough is over, reestablishing normal pressures. Paroxysmal coughing, however, does not allow blood to return between coughs, with the result that very high luminal pressures may be generated, sufficient to damage veins. A history of coughing, vomiting or choking is not uncommon in otherwise normal infants with retinal and subdural bleeding. Our findings suggest that paroxysmal coughing could account for such bleeding in some cases.

Arachnoid cysts in adults: long-term follow-up of patients treated with internal shunts to the subdural compartment

BACKGROUND

We have previously presented an alternative method for surgical decompression of intracranial arachnoid cysts. This minimally invasive method, with insertion of an internal shunt from the cyst to the subdural compartment, seemed to be an efficient and simple, and hence promising technique. The aim of the present study was to investigate the long-term results of this procedure.

METHODS

This study is a questionnaire-based retrospective study that includes 31 adult patients (>18 years) who were operated on in our department for an arachnoid cyst in the temporal fossa or overlying the frontal convexity with the internal shunt technique between April 1990 and October 2003. Follow-up ranged from 15 months to 14.8 years (mean = 8.2 years).

RESULTS

Of the patients, 83% were asymptomatic or had insignificant complaints at follow-up. A total of 17% reported no reduction of the preoperative complaints. No patient experienced worsening of the symptoms. The cyst was no longer visible on postoperative radiologic examinations in 37% of the patients. In 37%, the postoperative fluid volume was less than 50% of the original volume. In 13%, the cyst volume was reduced but the postoperative volume was greater than 50% of the original cyst volume. Thus, the cyst was unchanged in only 13% of the patients. There was no correlation between volume reduction and clinical improvement. A complication (subdural hygroma or hematoma) occurred in 7 patients, all with temporal cysts, leading to reoperation in 4. None of the complications caused permanent neurologic deficits or invalidity. Seven patients were reoperated on because of suspected or established treatment failure.

CONCLUSIONS

The internal shunt technique is a relatively simple, safe, and efficient alternative method for treatment of arachnoid cysts. It should be considered a valuable alternative in the treatment of arachnoid cysts.

Diagnostic method for differentiating external hydrocephalus from simple subdural hygroma

Object

The various terms used to describe subdural fluid collection—“external hydrocephalus,” “subdural hygroma,” “subdural effusion,” “benign subdural collection,” and “extraventricular obstructive hydrocephalus”—reflect the confusion surrounding the diagnoses of these diseases. Differentiating external hydrocephalus from simple subdural hygroma may be difficult, but the former appears to be a distinct clinical entity separate from the latter. In this report, the authors present a diagnostic method for differentiating external hydrocephalus from simple subdural hygroma, based on their clinical experience in treating subdural fluid collection after mild head trauma.

Methods

Twenty patients with subdural fluid collection after mild head trauma were included in this study. Ventricle size was measured using a modified frontal horn index (mFHI); that is, the largest width of the frontal horns divided by the bicortical distance in the same plane, instead of the inner table distance. Bur hole trephination was performed on the appearance of a subdural fluid collection thicker than 15 mm on computed tomography (CT), persistent (longer than 4 weeks) or increasing in size, and accompanied by neurological symptoms (confusion or memory impairment). During the procedure, subdural pressure was measured using a manometer before opening the dura mater. Subdural pressure varied among the patients, ranging from 3 to 27.5 cm H2O. Four patients with a subdural pressure greater than 15 cm H2O had hydrocephalus after surgery (p < 0.05). Hydrocephalus developed in a pediatric patient (2 years old) with a subdural pressure of 12 cm H2O. All of the patients in whom hydrocephalus developed after bur hole trephination had had enlarged ventricles (mFHI > 33%) on preoperative CT scans.

Conclusions

Monitoring subdural pressure may be a valuable tool for differentiating subdural hygroma from external hydrocephalus in patients with mild head trauma. Additionally, the mFHI reflects the nature of the subdural collection more accurately than the standard frontal horn index.

Subacute spinal subdural hematoma associated with intracranial subdural hematoma

We describe a subacute spinal subdural hematoma in a patient with psot-traumatic subacute intracranial subdural hematoma. CT and MRI demonstrated hematoma within the interhemispheric subdural space and at the lumbar posterior subdural space which extended from the L1 to the S2 level. The lesion showed high signal intensity on both T1 and T2 weighted images. Surgical decompression of the spinal subdural hematoma was performed. The symptoms completely resolved after surgery. Spinal subdural hematoma may be concomitant with or may occur after intracranial subdural hematoma. If a patient with intracranial subdural hematoma complains of low back pain and weakness in both legs; lumbosacral MR examination should be performed to exclude spinal subdural hematoma.

Patient-specific model of brain deformation: application to medical image registration

This contribution presents finite element computation of the deformation field within the brain during craniotomy-induced brain shift. The results were used to illustrate the capabilities of non-linear (i.e. accounting for both geometric and material non-linearities) finite element analysis in non-rigid registration of pre- and intra-operative magnetic resonance images of the brain. We used patient-specific hexahedron-dominant finite element mesh, together with realistic material properties for the brain tissue and appropriate contact conditions at boundaries. The model was loaded by the enforced motion of nodes (i.e. through prescribed motion of a boundary) at the brain surface in the craniotomy area. We suggest using explicit time-integration scheme for discretised equations of motion, as the computational times are much shorter and accuracy, for practical purposes, the same as in the case of implicit integration schemes. Application of the computed deformation field to register (i.e. align) the pre-operative images with the intra-operative ones indicated that the model very accurately predicts the displacements of the tumour and the lateral ventricles even for limited information about the brain surface deformation. The prediction accuracy improves when information about deformation of not only exposed (during craniotomy) but also unexposed parts of the brain surface is used when prescribing loading. However, it appears that the accuracy achieved using information only about the deformation of the exposed surface, that can be determined without intra-operative imaging, is acceptable. The presented results show that non-linear biomechanical models can complement medical image processing techniques when conducting non-rigid registration. Important advantage of such models over the previously used linear ones is that they do not require unrealistic assumptions that brain deformations are infinitesimally small and brain stress-strain relationship is linear.

Local elevation of the anti-inflammatory interleukin-10 in the pathogenesis of chronic subdural hematoma

We investigated the relationship between inflammatory and anti-inflammatory cytokines in the pathogenesis of chronic subdural hematoma (CSDH) by measuring the plasma and subdural fluid levels of interleukin-6 (IL-6), interleukin-8 (IL-8), and interleukin-10 (IL-10). The levels of IL-6, IL-8 and IL-10 were measured in the subdural fluid obtained from 34 patients with CSDH, using the enzyme-linked immunosorbent assay. The patients were classified into a high IL-10 group and a low IL-10 group according to the level of IL-10 in their subdural fluid samples. The subdural fluid levels of IL-6 and IL-8 were significantly higher in the high IL-10 group than in the low IL-10 group (P<0.05). A tendency for the patients in the low IL-10 group to show the separated or layer type of pattern on the CT scans was noted.

Atypical traumatic craniocervical junction focal spinal subdural hematoma

Spinal subdural hematoma (SSDH) is a rare entity and post-traumatic cervical SSDH is very rare. Review of the literature revealed 8 reported cases of traumatic SSDH and only 2 were cervical. The exact mechanism and pathogenesis of SSDHs are unclear. There are still controversies about the source of bleeding and mechanisms of formation of a hematoma. Here we report a case of a unique traumatic craniocervical junction focal subdural hematoma in an 8-year-old boy and discuss the possible mechanisms of SSDHs in trauma cases.

Medial portion of the cavernous sinus: quantitative analysis of the medial wall

Pituitary tumors invade the cavernous sinus via the medial wall. Researchers have speculated that this wall is composed of dura and that substances secreted by tumors might damage this barrier. In contrast to the lateral wall, little is known about the structure of the medial wall of the cavernous sinus (MWCS). This study provides the first detailed quantitative (thickness) and qualitative (histological) assessment of the MWCS. Eighteen sellar-parasellar tissue blocks were obtained from adult human autopsies. Ten specimens were used for microsurgical dissection and macroscopic anatomical description. Eight specimens were used for histopathological study and for recording computer measurements of MWCS thickness. Each of these eight specimens was divided into three approximately equal-sized pieces, with cuts made in the coronal plane from posterior to anterior starting at the anterior level of the pituitary stalk. Wall thicknesses were compared in the three different regions (posterior, middle, anterior), and also on the left vs. the right sides. The investigations showed that the MWCS is a distinct dural layer that forms a barrier between the medial venous space of the cavernous sinus and the pituitary gland. The mean thickness of the 48 total (left and right) MWCS observed in the 24 sections examined was 0.195 +/- 0.066 mm (range = 0.080-0.387 mm). This wall is composed of loosely arranged collagen fibers that comprise a specific layer known as "meningeal dura." The posterior third of the MWCS was significantly thinner than the middle third (P = 0.0014) or anterior third (P = 0.0001). No macro- or microscopic defects were observed in any of the MWCS in the 18 specimens. The thinness of the posterior MWCS suggests that this is the most likely path for extension of pituitary tumors into the cavernous sinus.

Wave-like appearance of diffuse pachymeningeal enhancement associated with intracranial hypotension

Diffuse pachymeningeal enhancement on magnetic resonance (MR) imaging is important in identifying spontaneous and secondary intracranial hypotension (IH) [cerebrospinal fluid (CSF) hypovolemia] in patients with postural headache, because CSF pressure at lumbar puncture is variable. We examined the pachymeningeal enhancement pattern in patients with IH. MR imaging findings of pachymeningeal enhancement were examined before and after treatment in seven consecutive patients with spontaneous IH and one patient with IH after lumbar puncture. Diffuse non-nodular dural enhancement was observed in all patients. Characteristic thick, uninterrupted, enhancement was observed, mainly in the dura of the frontal, temporal, and retroclival regions, and the tentorium. Thin and uninterrupted, or partially interrupted, enhancement was observed, mainly in the parieto-occipital region and cerebellar convexity. Curved linear enhancement was observed along the calvarium of all patients. A wave-like appearance, a clear pattern of dural unevenness parallel to the brain, was detected in the frontal and temporal regions, near the base, in all patients. A wave-like appearance, especially in the frontal and temporal base, may be a characteristic MR imaging indicator of IH.

Chronic subdural haematoma: surgical treatment and outcome in 1000 cases

Chronic subdural haematoma (CSDH) is one of the most common clinical entities in daily neurosurgical practice. To evaluate the clinical features, computed tomography findings, surgical results, and complications our series was statistically analysed to elucidate the factors affecting the post-operative outcome. A retrospective study (1980-2002) of the records of 1000 patients harbouring 1097 chronic subdural haematoma treated with burr-hole craniotomy with closed-system drainage was carried out. The series included 628 males and 372 females, age range 12-100 years, mean age 72.7+/-11.4 years. The mean interval from trauma to appearance of clinical symptoms was 49.1+/-7.4 days (15-751). The principal symptom was headache (29.7%) in the over 70s, and behavioural disturbance (33.8%) in the under 70s. The CSDH was right sided in 432 patients, left sided in 471, and bilateral in the remaining 97 cases. Post-operative complications occurred in 196 patients and 21 patients died in hospital. Poor prognosis was related to patient's age (>70) and clinical grade on admission (grades 0-2 versus grades 3-4).

Idiopathic Interdural Hematoma Looking Like a "Chinese Dumpling"-Case Report-

A 79-year-old man presented with an interdural hematoma manifesting as headache. Computed tomography revealed a right parietal intracranial hematoma. Magnetic resonance imaging revealed the hematoma had divided the dura mater into two layers. Craniotomy was performed and a dural pouch containing a solid hematoma was totally removed. Histological examination showed the hematoma had divided the meningeal dura into two layers. This case confirms the location of interdural hematoma.

Inflammation markers and risk factors for recurrence in 35 patients with a posttraumatic chronic subdural hematoma: a prospective study

Object. To evaluate the role of local inflammation in the pathogenesis and postoperative recurrence of chronic subdural hematoma (CSDH), the authors conducted an investigation in a selected group of patients who could clearly recall a traumatic event and who did not have other risk factors for CSDH. Inflammation was analyzed by measuring the concentration of the proinflammatory and inflammatory cytokines interleukin (IL)-6 and IL-8. The authors also investigated the possible relationship between high levels of local inflammation that were measured and recurrence of the CSDH.

Methods. A prospective study was performed between 1999 and 2001. Thirty-five patients who could clearly recall a traumatic event that had occurred at least 3 weeks previously and who did not have risk factors for CSDH were enrolled. All patients were surgically treated by burr hole irrigation plus external drainage.

The concentration of inflammatory cytokines was very high in the lesion, whereas it was normal in serum. In five cases in which recurrence occurred, concentrations of both IL-6 and IL-8 were significantly increased (p < 0.01) in comparison with cases without a recurrence. In a layering hematoma, the IL-6 and IL-8 concentrations were significantly higher (p < 0.05). Layering CSDHs were also significantly correlated with recurrence. Trabecular hematoma had the lowest cytokine levels and the longest median interval between trauma and clinical onset. The interval from trauma did not significantly influence recurrence, although it did differ significantly between the trabecular and layering CSDH groups. Concentrations of IL-6 and IL-8 in the CSDHs did not differ significantly in relation to either the age of the hematoma (measured as the interval from trauma) or the age of the patient.

Conclusions. Brain trauma causes the onset of an inflammatory process within the dural border cell layer; high levels of inflammatory cytokines were significantly correlated with recurrence and layering CSDH. A prolonged postoperative antiinflammatory medicine given as prophylaxis may help prevent the recurrence of a CSDH.

Spinal subdural hematoma revealing hemophilia A in a child: A case report

BACKGROUND: Intraspinal bleeding especially in the form of subdural hematoma is rare in hemophiliacs. In the present case, we report a neglected hemophilic A child with such a problem and discuss its management options. CASE PRESENTATION: A 9-year old hemophilic A boy presented with quadriparesis, confusion and meningismus after a fall 4 days previously. There was no sign of direct trauma to his back. His CT Scan and MRI showed spinal extramedullary hematoma extended from C5 to L2. We corrected the factor VIII level, but two days later, the patient's lower limbs weakened to 1/5 proximally as well as distally. We performed a laminectomy from T11 to L2, according to the level of the maximal neurological deficit and recent deterioration course. The subdural hematoma was evacuated. The hematoma in other spinal levels was managed conservatively. In the week following the operation, the patient's neurological status approached normal. CONCLUSION: This case calls attention to the clinical manifestation, radiological features and management options of the rarely reported intraspinal hematoma in hemophilic children. Although this case has been managed operatively for its hematoma in the thoracolumbar region, at the same time it can be considered a successful case of conservative management of intraspinal hematoma in the cervicothoracic region. Both conservative and surgical management could be an option in managing these patients considering their neurological course.

Architecture of arachnoid trabeculae, pillars, and septa in the subarachnoid space of the human optic nerve: anatomy and clinical considerations

AIMS

To describe the anatomy and the arrangement of the arachnoid trabeculae, pillars, and septa in the subarachnoid space of the human optic nerve and to consider their possible clinical relevance for cerebrospinal fluid dynamics and fluid pressure in the subarachnoid space of the human optic nerve.

METHODS

Postmortem study with a total of 12 optic nerves harvested from nine subjects without ocular disease. All optic nerves used in this study were obtained no later than 7 hours after death, following qualified consent for necropsy. The study was performed with transmission (TEM) and scanning electron microscopy (SEM).

RESULTS

The subarachnoid space of the human optic nerve contains a variety of trabeculae, septa, and stout pillars that are arranged between the arachnoid and the pia layers of the meninges of the nerve. They display a considerable numeric and structural variability depending on their location within the different portions of the optic nerve. In the bulbar segment (ampulla), adjacent to the globe, a dense and highly ramified meshwork of delicate trabeculae is arranged in a reticular fashion. Between the arachnoid trabeculae, interconnecting velum-like processes are observed. In the mid-orbital segment of the orbital portion, the subarachnoid space is subdivided, and can appear even loosely chambered by broad trabeculae and velum-like septa at some locations. In the intracanalicular segment additionally, few stout pillars and single round trabeculae are observed.

CONCLUSION

The subarachnoid space of the human optic nerve is not a homogeneous and anatomically empty chamber filled with cerebrospinal fluid, but it contains a complex system of arachnoid trabeculae and septa that divide the subarachnoid space. The trabeculae, septa, and pillars, as well as their arrangement described in this study, may have a role in the cerebrospinal fluid dynamics between the subarachnoid space of the optic nerve and the chiasmal cistern and may contribute to the understanding of the pathophysiology of asymmetric and unilateral papilloedema. All the structures described are of such delicate character that they can not even be visualised with high resolution magnetic resonance imaging (MRI).

MRI depiction of chronic intradural (subdural) hematoma in evolution

The usual chronic subdural hematoma encountered in the elderly is actually thought to be a chronic intradural hematoma, which has been described clinically and anatomically. However, the evolution of how this chronic hematoma occurs remains enigmatic. We report the first magnetic resonance (MR) depiction of an apparent chronic intradural hematoma in evolution over several months in a 61-year-old man after a minimal head injury. The time delay from injury, subsequent focal pachymeningeal T1-gadolinium enhancement, and apparent splitting of the pachymeninges by proven chronic hematoma should serve as a stimulus for further MR investigations of this interesting process.

Adult cranial dura II: venous sinuses and their extrameningeal contributions

This is the second of two articles designed to provide detailed user-friendly schematics of the adult dural vascular anatomy. It supplements the first article on the intrinsic meningeal arteries and veins by describing the dural venous sinuses along with their three remaining connections: to the brain, to the diploë, and to the extracranial soft tissues. The discussion of this anatomy is supplemented by illustrative pathologic insights. This information will assist in interpreting neuroimaging studies, communication with clinicians, and teaching of this complex subject.

Traumatic spinal subdural hematoma with spontaneous resolution

STUDY DESIGN

A case report with a literature review is presented.

OBJECTIVE

To describe and review the clinical presentations, characteristic findings from imaging studies, and treatment of traumatic spinal subdural hematoma.

SUMMARY OF BACKGROUND DATA

Traumatic spinal subdural hematoma is uncommon, and only eight cases have been reported in the literature. Concomitant intracranial and spinal subdural hematoma in the same patient has not been well studied.

METHODS

A case of concomitant spinal and intracranial subdural hematoma is reported as well as a review of the literature.

RESULTS

Including our patient, we found that five of the nine patients with traumatic spinal subdural hematoma also had intracranial hematoma. We hypothesize that the mechanism of traumatic spinal subdural hematoma may be associated with intracranial events. Recognition of blood products in magnetic resonance imaging scans is important to distinguish spinal subdural hematoma from other spinal lesions. It is generally agreed that prompt laminectomy with evacuation of hematoma should be performed before irreversible damage to the spinal cord occurs. However, including our patient, three of the nine reported cases with thoracic or lumbar subdural hematoma resolved spontaneously with conservative treatment.

CONCLUSIONS

This 12-year-old boy illustrated the rapid spontaneous resolution of traumatic subdural hematoma in both left hemisphere and lumbar spine with conservative treatment. This report suggests a possible role of conservative management for traumatic lumbar subdural hematoma, especially when the patients already have neurologic recovery.

Adult cranial dura I: intrinsic vessels

This is the first of two articles designed to provide user-friendly schematics of the adult dural vascular anatomy. It describes the intrinsic meningeal arteries and veins of the skull base/cranial vault and the dural partitions (the tentorium, falx cerebelli, and falx cerebri). The discussion of this anatomy is supplemented by illustrative pathologic insights. The second article focuses on the dural sinuses and their remaining tributaries from the brain, diploë, and emissary veins from the extracranial soft tissues. This information will assist in interpreting neuroimaging studies, communications with clinicians, and teaching of this difficult subject.

A comparative study of the treatment of chronic subdural hematoma--burr hole drainage versus burr hole irrigation

BACKGROUND

Several surgical procedures have been reported for the treatment of chronic subdural hematoma. Whether irrigation is required is not clear. We compared the results of treatment of chronic subdural hematoma obtained with burr hole drainage and burr hole irrigation retrospectively.

METHODS

Forty patients with chronic subdural hematoma underwent surgery at our institution in the last 3 years. The first 20 patients were treated by burr hole irrigation (irrigation group), while the last 20 patients underwent burr hole drainage (drainage group). The rates of recurrence, changes in hematoma size, and number of days of postoperative hospitalization for the two groups were compared. No significant differences were found between the two groups in the presence of head injury, alcohol consumption, age, gender, or preoperative hematoma size.

RESULTS

Duration of postoperative hospitalization was 14.1 days in the drainage group and 25.5 days in the irrigation group. Recurrence was observed in 1 case (5%) in the drainage group, and in 5 cases (25%) in the irrigation group. In the drainage group, postoperative hematoma size was significantly decreased compared to preoperative hematoma size on the first postoperative day, after which change in hematoma size was minimal. On the other hand, in the irrigation group, hematoma size was decreased on the first postoperative day, but not to a significant extent.

CONCLUSION

For treatment of chronic subdural hematoma, postoperative hospitalization was shorter and the recurrence was less frequent with drainage than with irrigation.

Acute nontraumatic spinal subdural hematomas in three patients

STUDY DESIGN

The clinical data, magnetic resonance imaging, intraoperative findings, and functional outcome were reviewed for three patients under anticoagulant therapy who experienced acute nontraumatic spinal subdural hematoma.

OBJECTIVES

To draw attention to this rare complication of anticoagulant therapy and to assess the magnetic resonance findings and clinical outcome of patients with spinal subdural hematoma after surgical evacuation.

SUMMARY OF BACKGROUND DATA

Among intraspinal hematomas, spinal subdural hematomas are by far the least common. Magnetic resonance findings have been demonstrated in only a few cases of spinal subdural hematomas. The timing of the operation and the anatomic location of the hematoma essentially determine the functional outcome.

METHODS

Three case reports of spinal subdural hematomas in patients receiving anticoagulant therapy are presented. Particular interest was given to the clinical and magnetic resonance data, the intraoperative findings, and the functional outcome.

RESULTS

The three patients each had a complete preoperative neurologic deficit. Sagittal T1- and T2-weighted magnetic resonance images of the spine proved to have high sensitivity for defining the type of bleeding and delineating the craniocaudal extension of the hematoma. Surgical evacuation was performed within 26 hours after the onset of symptoms. Intraoperative findings showed the hematoma to be confined between the dura and the arachnoid in two patients, and to be associated with rupture into the subarachnoid space in one patient. Postoperative recovery was incomplete in two patients, and did not improve in the remaining patient.

CONCLUSIONS

Spinal subdural hematoma must be considered in patients under anticoagulant therapy with spontaneous signs of acute spinal cord or cauda equina compression. Magnetic resonance imaging with sagittal T1- and T2-weighted images were adequate and reliable for diagnosis of spinal subdural hematoma. On the basis of previous studies and the authors' intraoperative findings, spinal subdural hematomas could be viewed as spinal dural border hematomas. The level of preoperative neurologic deficit seemed to be critical for recovery despite prompt surgical evacuation.

Burr-hole versus twist-drill drainage for the evacuation of chronic subdural haematoma: a comparison of clinical results

BACKGROUND

Most neurosurgeons remove clinically symptomatic subdural haematomata, but the techniques they choose remain controversial.

METHOD

The results from sixty-two patients diagnosed with chronic subdural haematoma were evaluated for technique, postoperative computerized tomography (CT) scan results, and complications.

RESULTS

Eleven patients had haematomata evacuated using twist-drill plus drain, 37 patients had haematomata evacuated with burr-hole only, and 14 patients were evacuated with burr-hole plus drain. Of the patients who underwent twist-drill and closed system drainage (CSD), 43% had smaller lesions on CT follow-up scans, as compared with 74% of those who underwent the burr-hole only procedure, and 65% with burr-holes with drains. Clinical outcome results showed that 64% of twist-drill and CSD patients deteriorated as compared with 16% of those with burr-hole only and 7% with burr-holes and CSDs. Sixty-four per cent of twist-drill patients required repeat evacuations as compared with 11% of those with burr-holes only, and 7% with burr-holes plus drains.

CONCLUSION

The results at our institution indicate that burr-hole evacuation for chronic subdural haematoma is superior to twist-drill evacuation with respect to clinical outcomes and complications.

Subduroperitoneal drainage for subdural hematomas in infants: results in 244 cases

OBJECT

Subduroperitoneal drainage (SDPD) is commonly used in the treatment of infantile subdural hematomas (SDHs). Few studies have focused on this technique and most series have included SDHs of various origins in children of different ages. The surgical procedure is not standardized and results achieved using this technique have not been well documented. The authors reviewed their cases of traumatic SDH treated with SDPD in infants (< 2 years of age). Their standard technique includes bilateral SDPD whenever the SDH is bilateral, placement of a free shunt, and systematic removal of the drainage unit after a few months.

METHODS

The authors performed SDPD in 244 infants with traumatic SDH. The patients' SDHs were controlled by SDPD in 241 cases, and 78.9% of the patients recovered to live a normal life. Complications of SDPD occurred in 38 patients (15.6%): obstruction in 22 cases (9%), infection in eight cases (3.28%), and internal hydrocephalus in eight cases (3.28%). Early complications could be ascribed to surgical technique, delayed complications were associated with the severity of the initial clinical presentation, and late complications were time dependent and unrelated to initial clinical severity. Poor clinical outcome was correlated to the severity of the initial presentation, but not to complications of surgery.

CONCLUSIONS

Because of its efficacy and low complication rate, SDPD is the procedure of choice when subdural taps fail to control SDH. The authors prefer bilateral drainage because of the low rate of complications. Drains should be systematically removed after a few months to prevent long-term complications.

Spontaneous intracranial hypotension

Spontaneous intracranial hypotension (SIH) is typically manifested by orthostatic headaches that may be associated with one or more of several other symptoms, including pain or stiffness of the neck, nausea, emesis, horizontal diplopia, dizziness, change in hearing, visual blurring or visual field cuts, photophobia, interscapular pain, and occasionally face numbness or weakness or radicular upper-limb symptoms. Cerebrospinal fluid (CSF) pressures, by definition, are quite low. SIH almost invariably results from a spontaneous CSF leak. Only very infrequently is this leak at the skull base (cribriform plate). In the overwhelming majority of patients, the leak is at the level of the spine, particularly the thoracic spine and cervicothoracic junction. Sometimes, documented leaks and typical clinical and imaging findings of SIH are associated with CSF pressures that are consistently within limits of normal. Magnetic resonance imaging of the head typically shows diffuse pachymeningeal gadolinium enhancement, often with imaging evidence of sinking of the brain, and less frequently with subdural fluid collections, engorged cerebral venous sinuses, enlarged pituitary gland, or decreased size of the ventricles. Radioisotope cisternography typically shows absence of activity over the cerebral convexities, even at 24 or 48 hours, and early appearance of activity in the kidneys and urinary bladder, and may sometimes reveal the level of the leak. Although various treatment modalities have been implemented, epidural blood patch is probably the treatment of choice in patients who have failed an initial trial of conservative management. When adequate trials of epidural blood patches fail, surgery can offer encouraging results in selected cases in which the site of the leak has been identified. Some of the spontaneous CSF leaks are related to weakness of the meningeal sac, likely in connection with a connective tissue abnormality.

Spontaneous intracranial hypotension with diffuse dural enhancement of the spinal canal and transient enlargement of the pituitary gland

Spontaneous intracranial hypotension is a rare phenomenon characterized by postural headache, neck rigidity, nausea and vomiting. Imaging findings on magnetic resonance imaging (MRI) is characteristic with diffuse intracranial pachymeningeal thickening and enhancement following intravenous gadolinium. We present a case of spontaneous intracranial hypotension with two unusual imaging findings; pachymeningeal enhancement of the spinal canal and enlargement of the pituitary gland in addition to the diffuse intracranial pachymeningeal enhancement. In this case report, we will discuss the clinical features, MRI findings and underlying pathophysiology of this rare condition.

Spontaneous intracranial hypotension

Spontaneous intracranial hypotension (SIH) is typically manifested by orthostatic headaches that may be associated with one or more of several other symptoms, including pain or stiffness of the neck, nausea, emesis, horizontal diplopia, dizziness, change in hearing, visual blurring or visual field cuts, photophobia, interscapular pain, and occasionally face numbness or weakness or radicular upper-limb symptoms. Cerebrospinal fluid (CSF) pressures, by definition, are quite low. SIH almost invariably results from a spontaneous CSF leak. Only very infrequently is this leak at the skull base (cribriform plate). In the overwhelming majority of patients, the leak is at the level of the spine, particularly the thoracic spine and cervicothoracic junction. Sometimes, documented leaks and typical clinical and imaging findings of SIH are associated with CSF pressures that are consistently within limits of normal. Magnetic resonance imaging of the head typically shows diffuse pachymeningeal gadolinium enhancement, often with imaging evidence of sinking of the brain, and less frequently with subdural fluid collections, engorged cerebral venous sinuses, enlarged pituitary gland, or decreased size of the ventricles. Radioisotope cisternography typically shows absence of activity over the cerebral convexities, even at 24 or 48 hours, and early appearance of activity in the kidneys and urinary bladder, and may sometimes reveal the level of the leak. Although various treatment modalities have been implemented, epidural blood patch is probably the treatment of choice in patients who have failed an initial trial of conservative management. When adequate trials of epidural blood patches fail, surgery can offer encouraging results in selected cases in which the site of the leak has been identified. Some of the spontaneous CSF leaks are related to weakness of the meningeal sac, likely in connection with a connective tissue abnormality.

Anatomical spaces: a review

The meaning and usefulness of the phrase "an anatomical space" are questioned. The concept of anatomical space is examined from historical, developmental, and topographical viewpoints. The validity of the idea and usage of the term "potential space" is discussed. The criterion of Haines (1991) is adopted, that only "spaces" or "cavities" that are lined with a "mesothelial" layer and that can repeatedly be opened up without tissue damage should be considered "true potential spaces." A plea is made that all other anatomical "spaces" be designated "compartments."

Lateral ventricular meningioma encapsulated by the dura-like membrane

The first case of a ventricular meningioma that was encapsulated by the dura-like membrane is reported. Magnetic resonance imaging (MRI) showed a heterogeneous mass with a low intensity rim in the trigone of the right lateral ventricle of a 63-year-old male. Histological examination revealed that the tumor was a transitional meningioma encapsulated by a thick dura-like membrane. Moreover, abundant clusters of the dura-like connective tissue existed in the tumor, indicating that both the dura-like capsule and the dura-like clusters in the tumor were created by the tumor cells.

The effects of subdural haematoma on spatial learning in the rat

Although memory deficits are one of the most persistent consequences of human subdural haematoma, cognitive functioning has hardly been investigated in the rat subdural haematoma model. In the present study, the effects on spatial learning of right- and left-sided unilateral subdural haematoma and of bilateral subdural haematoma induced above the sensorimotor cortical areas were evaluated. Spatial learning was assessed by standard acquisition in the Morris water escape task (five sessions). Additional issues addressed were sensorimotor functioning (footprint analysis), recovery of cognitive functioning (tested by an overtraining and a reversal training) and replicability of induced cognitive deficits. Following unilateral subdural haematoma surgery, hardly any impairments in the Morris water escape task were observed: rats with a unilateral right-sided subdural haematoma showed very mild, transient deficits, whereas rats with left-sided subdural haematoma were indistinguishable from controls. Bilateral subdural haematoma surgery led to a clear, although transient, performance deficit. We conclude that animals with bilateral subdural haematoma may provide a promising cognitive deficit model for investigating recovery of function.

Spontaneous cerebrospinal fluid leaks: from intracranial hypotension to cerebrospinal fluid hypovolemia--evolution of a concept

Intracranial hypotension causes orthostatic headaches and diffuse pachymeningeal gadolinium enhancement on magnetic resonance imaging with or without subdural fluid collections or imaging evidence of descent of the brain. A review of the literature and my experience and investigations in the past decade reveal a broadening clinical and imaging spectrum of the syndrome. Besides the classic clinical-imaging syndrome of orthostatic headaches, diffuse pachymeningeal gadolinium enhancement, and low cerebrospinal fluid (CSF) pressure, several modes of presentation are recognized, including (1) the typical clinical-imaging syndrome with CSF pressures consistently within normal limits, (2) absence of diffuse pachymeningeal gadolinium enhancement with presence of low CSF pressures and typical clinical manifestations, and (3) absence of headaches despite low CSF pressures and presence of diffuse pachymeningeal gadolinium enhancement. Furthermore, in some patients with headaches, the orthostatic headaches may evolve into lingering chronic daily headaches, although they may be more prominent in upright positions. What determines the various clinical and imaging features of this syndrome seems to be the loss of CSF volume as the independent variable, while other manifestations, including clinical features, CSF pressures, and imaging abnormalities, are variables dependent on the CSF volume. The term CSF hypovolemia is proposed for this syndrome because the term intracranial hypotension no longer seems adequate to embrace all the variations that have emerged.

The spinal epidural space

The validity of the concept of an epidural 'space' within the vertebral canal is questioned. An attempt is made to locate the 'space' morphologically, developmentally, and topographically. Following Parkin and Harrison (1985), it is agreed that no actual 'space' exists in the intact living subject. It is suggested that the spinal epidural space satisfies the criteria of Haines (1991) to be considered a "true potential space." As such, and by analogy with other body cavities, it would be better termed the 'epidural cavity', as it was in the 1983 edition of the Nomina Anatomica.

Nontraumatic acute spinal subdural hematoma

✓ Acute subdural spinal hematoma occurs rarely; however, when it does occur, it may have disastrous consequences. The authors assessed the outcome of surgery for this lesion in relation to causative factors and diagnostic imaging (computerized tomography [CT], CT myelography), as well as eventual preservation of the subarachnoid space.

The authors reviewed 106 cases of nontraumatic acute subdural spinal hematoma (101 published cases and five of their own) in terms of cause, diagnosis, treatment, and long-term outcome.

Fifty-one patients (49%) were men and 55 (51%) were women. In 70% of patients the spinal segment involved was in the lumbar or thoracolumbar spine. In 57 cases (54%) there was a defect in the hemostatic mechanism. Spinal puncture was performed in 50 patients (47%). Late surgical treatment was performed in 59 cases (56%): outcome was good in 25 cases (42%) (in 20 of these patients preoperative neurological evaluation had shown mild deficits or paraparesis, and three patients had presented with subarachnoid hemorrhage [SAH]). The outcome was poor in 34 cases (58%; 23 patients with paraplegia and 11 with SAH).

The formation of nontraumatic acute spinal subdural hematomas may result from coagulation abnormalities and iatrogenic causes such as spinal puncture. Their effect on the spinal cord and/or nerve roots may be limited to a mere compressive mechanism when the subarachnoid space is preserved and the hematoma is confined between the dura and the arachnoid. It seems likely that the theory regarding the opening of the dural compartment, verified at the cerebral level, is applicable to the spinal level too. Early surgical treatment is always indicated when the patient's neurological status progressively deteriorates. The best results can be obtained in patients who do not experience SAH.

In a few selected patients in whom neurological impairment is minimal, conservative treatment is possible.

Extracellular matrix degradation by metalloproteinases and central nervous system diseases

Matrix metalloproteinases (MMPs) are a gene family of neutral proteases involved in normal and pathological processes in the central nervous system (CNS). Normally released into the extracellular space, MMPs break down the extracellular matrix (ECM) to allow cell growth and to facilitate remodeling. Proteolysis becomes pathological when the normal balance between the proteases and their inhibitors, tissue inhibitors to metalloproteinases (TIMPs), is lost. Cancer cells secrete neutral proteases to facilitate spread through the ECM. MMPs increase capillary permeability, and they have been implicated in demyelination. Neurological diseases, such as brain tumors, multiple sclerosis, Guillain-Barré, ischemia, Alzheimer's disease, and infections, lead to an increase in the matrix-degrading proteases. Two classes of neutral proteases have been extensively studied, namely the MMPs and the plasminogen activators (PAs), which act in concert to attack the ECM. After proteolytic injury occurs, the process of ECM remodeling begins, which can lead to fibrosis of blood vessels and gliosis. TIMPs are increased after the acute injury and may add to the fibrotic buildup of ECM components. Thus, an imbalance in proteolytic activity either during the acute injury or in recovery may aggravate the underlying disease process. Agents that affect the proteolytic process at any of the regulating sites are potentially useful in therapy.

Microanatomy of the hypophyseal fossa boundaries

OBJECT

The authors studied the heads of 17 adult cadavers and one fetus to clarify the anatomy of the sellar region, particularly the lateral boundaries of the hypophyseal fossa.

METHODS

Vascular injections and microdissection or histological techniques were used in this study. The roof of the cavernous sinuses and diaphragma sellae were part of a single horizontal dural layer that joined the two anterior petroclinoid folds. Laterally, the direction of this layer changed; it became the lateral wall of the cavernous sinus and joined the dura mater of the middle cerebral fossa. On the midline, this layer ballooned toward the sella through the diaphragmatic foramina, created a dural bag containing the hypophysis, and attached to the inferior aspect of the diaphragma sellae. As a consequence, no straight sagittal dural wall existed between the pituitary gland and cavernous sinus; the lateral border of the hypophyseal fossa was part of this anteroposterior and superoinferior convex bag. The authors stress the importance of the venous elements of the region and discuss the structure of the cavernous and coronary sinuses.

CONCLUSIONS

Invasion of the cavernous sinus makes surgery more risky and difficult and may necessitate modification of the surgical treatment plan. The preoperative diagnosis of cavernous sinus invasion is thus of great interest, but the possibility of normal lateral expansions of the pituitary gland must be kept in mind. A lateral expansion of this gland into the cavernous sinus was encountered in 29% of the specimens, and an adenoma that developed in such an expansion could easily mimic cavernous sinus invasion.

Intracranial hypotension syndrome: neuroimaging in five spontaneous cases and etiopathogenetic correlations

Intracranial hypotension (IH) is essential or, more frequently, secondary. This syndrome is characterized by severe postural headache and low opening cerebrospinal fluid (CSF) pressure; although other symptoms may exist. In this study five patients are investigated. Neuroimaging showed: on computerized tomography scan (CT), poor visualization of the cerebral sulci with small ventricles; on magnetic resonance imaging (MRI), subdural fluid collections with enhancement on the convexity, along the tentorium and in the upper cervix after administration of contrast medium and downward displacement of the brain. Radionuclide cisternography was normal in the two patients who underwent this treatment as well as the meningeal biopsy in another patient. In all patients the opening CSF pressure was low or unmeasurable. The clinical syndrome spontaneously recovered contextually to normalization of neuroradiological findings. The possible pathogenesis (dural border cell layer tear) was discussed and the importance of diagnostic confirmation with MRI and measurement of CSF pressure when IH is thought to be present was underlined.

Acute posttraumatic subdural hematomas: "intradural" computed tomographic appearance as a favorable prognostic factor

OBJECTIVE

Posttraumatic acute subdural hematoma carries a high postoperative mortality rate. Preservation of subarachnoid spaces in preoperative computed tomographic (CT) scans may be interpreted as a favorable prognostic factor.

METHODS

Thirty-one cases of posttraumatic acute subdural hematoma operated on consecutively, with an interval from trauma to surgery of less than 4 hours and a Glasgow Coma Scale score of less than 8, were reviewed. The immediate and long-term results were evaluated with reference to preoperative CT images, distinguishing cases with preserved subarachnoid spaces from the others.

RESULTS

In 5 of the 31 cases, preoperative CT scans showed intact subarachnoid spaces and the absence of blood in the cerebrospinal fluid. These cases presented a much better postoperative course than did the others.

CONCLUSION

The presence of intact subarachnoid spaces in CT scans for patients with acute subdural hematomas may be interpreted as an extremely favorable prognostic factor; this may be attributed to the protective effect of the integral visceral membrane of the hematoma, which prevents the diffusion of neurotoxic and vasoactive substances into the subarachnoid spaces. This group of hematomas was classified as "intradural," with reference to the concept of the "subdural compartment" described in studies conducted using an electron microscope.

[Idiopathic peri-cerebral enlargement in infants: simple anatomical variant or hemorrhagic risk factor?]

BACKGROUND

Idiopathic subarachnoid space enlargement (ISSE) is usually regarded as a benign lesion.

CASE REPORTS

Two infants, 6 and 8 months old respectively, were hospitalized for neurological disorders revealing subdural hematoma. The first one was drowsy after an apparent life threatening event. The CT scan showed a recent subdural hematoma with ISSE. The outcome was spontaneously uneventful. The second patient presented a febrile hemiconvulsion preceding a status epilepticus. The diagnosis of empyema complicating subdural hematoma with ISSE was done on MRI. Recovery occurred after a 3 week course of parenteral antibiotics and 1 year of antiepileptic treatment. In these two cases, there was no history of head injury and the retrospective study of cranial perimeter growth curves showed acceleration before the acute event.

CONCLUSION

The reputation of benignity is not usurped regarding the ISSE. Nevertheless, it must be recognized as a factor furthering emergence of subdural hematoma, even in absence of injury context.

Subdural injection of contrast medium during cervical myelography

Three patients (1 dog, 2 horses) are described where myelography was complicated, purportedly by injection of contrast medium into the meninges superficial to the subarachnoid space. Contrast medium injected in this location in a cadaver tended to accumulate dorsally within the vertebral canal, deep to the dura mater but superficial to the subarachnoid space. The ventral margin of the pooled contrast medium had a wavy or undulating margin and the dorsal margin was smooth. Pooled contrast medium was believed to be sequestered within the structurally weak dural border cell layer between the dura mater and arachnoid membrane, or the so-called subdural space.