Fig. 22.1
Normal pressure hydrocephalus: (a) CT at diagnosis. (b–d) CT showing the emergence of a left subdural hygroma at 3 months after shunting
The treatment options for children or adults with extra-axial fluid collections include surgical treatment in symptomatic cases or observation in asymptomatic patients. In the former therapeutic options comprise serial percutaneous drainage, burr hole fluid drainage with or without a closed external system, fluid shunting to the peritoneum or other cavities and craniectomy with fluid evacuation [24]. In all cases shunt occlusion/ligation is recommended to raise intraventricular pressure thereby reducing the pressure difference between the subdural and intraventricular compartments.
Several treatment options for the management of these patients have been proposed [3] that resulted in:
(a)
Resolution without treatment: 85 % of subdural hygromas resolved spontaneously and resolution was greater and faster in younger patients.
(b)
Resolution by surgical drainage and shunt removal: though a good solution in Carmel et al.’s experience patients needed re-shunting.
(c)
Resolution by increasing the valve pressure with or without fluid drainage. This was the most efficacious treatment. If the patient has a programmable valve, the opening pressure should be increased, whereas in fixed pressure shunts, the valve must be replaced with a higher-pressure device. If valve replacement is not tolerated, evacuation of the hygroma may be necessary (Fig. 22.2).
Fig. 22.2
Hydrocephalus after idiopathic subarachnoid haemorrhage. CT cuts showing (a) haemorrhage at admission, (b) ventricular dilatation 1 month after the haemorrhage and (c–e) appearance of left subdural hygromas and right subdural hematoma after shunting. (f) One month after raising the valve pressure at 1 month
The key criterion for the prevention of subdural collections is the correct choice of shunt. Though most authors claim programmable valves not only reduced the incidence of subdural hygromas significantly by altering the pressure, other authors assert that programmable valves do not influence the incidence of subdural fluid collections as compared to fixed-pressure valves [44]. Siphoning is inherent to any differential-pressure valve system, which allows for sudden ventricle decompression and in turn for development of a subdural hygroma. A further explanation for subdural hygroma formation is that surgeons fail to programme the valve properly. Data from the Dutch normal-pressure hydrocephalus study found that subdural effusions occurred in 71 % of patients treated with a low-pressure shunt and in 34 % of patients with a medium-pressure shunt system [2]. The benefits of adjustable shunts are further reinforced in a report by Zemack and Romner [46], who concluded that non-invasive shunt adjustment improved outcomes for patients with normal pressure hydrocephalus (NPH) after reporting a 5-year survival rate of 80.2 % for adjustable shunts, with good to excellent outcomes observed in 78.1 % of people with idiopathic NPH.
22.2.2 Subdural Haematomas After Ventricular Shunting
The incidence of subdural haematomas related to hydrocephalus treatment varied considerably in early published reports (from 4.5 to 21 %), but this figure has fallen sharply to 4–5 % as CT scans have become a routine procedure in the follow-up of shunt patients. Though most subdural haematomas appearing after hydrocephalus treatment, regardless of the technique employed, are chronic with subacute evolution, acute subdural haematoma cases have also been reported [17].
Pathogenesis is probably no different for subdural haematoma formation of any aetiology, but the negative ventricular pressure produced by the shunting drainage appears to be an important additional predisposing factor [29, 38].
In a series of 1,000 CSDH (age 12–100 years) operated over a 22-year period, only six cases (0.6 %) had a previously implanted ventriculoperitoneal shunt [14]. However, the true incidence of CSDH after shunting is unknown.
Samuelson et al. [34] pointed out that patients with NPH were found to be particularly susceptible to subdural haematomas formation following ventricular shunt placement, in contrast to the lower incidence of SDH development following high-pressure hydrocephalus treatment.
In most instances subdural haematomas in shunted patients do not cause specific symptomatology (i.e., headache, confusion, lethargy and vomiting are the most common symptoms, being focal neurologic deficits unusual), which is identical for non-functioning shunts.
When the haematomas are symptomatic, they require surgical treatment (burr hole or craniotomy) depending on the type of haematoma (chronic or acute) and often shunt ligation to prevent reaccumulation or SDH expansion.
However, the most crucial factor for preventing this complication is the use of an adjustable valve. This type of shunt not only enables the nonsurgical increase of valve settings to prevent subdural effusions but also offers the added benefit of high-pressure drainage to aid subdural haematoma treatment (Fig. 22.3).
Fig. 22.3
Posttraumatic hydrocephalus: (a) CT scan at diagnosis. (b–d) Chronic subdural hematoma on the right hemisphere 2 months after shunting; there was no evidence of a head injury
22.3 Subdural Collections Following Neuroendoscopic Procedures
Endoscopic third ventriculostomy (ETV) has become a popular treatment particularly for cases of obstructive hydrocephalus though it may be used for the management of several conditions such as colloid cysts, fenestration of arachnoid cyst, etc. [12].
The main advantage of treating hydrocephalus by a third ventriculostomy is the avoidance of a diversionary cerebrospinal fluid shunt, thereby sparing the patient the distress and the risks of further surgery due to shunt complications. This procedure offers advantages but entails certain drawbacks, i.e., intra-and post-operative complications. The technical problems and complications of ETV have been well documented such as adverse effects on the cardiovascular system, injury of the fornix with memory deficits, hypothalamic dysfunction, and injury to the basilar artery or cranial nerves ([7, 41]).
22.3.1 Subdural CSF Hygromas Following Neuroendoscopic Procedures
Subdural effusion is a rare complication that is probably more frequent than reported in the literature [43]. Following ETV, ipsilateral, contralateral or bilateral subdural effusions may occur, primarily on the operated side or on both sides, but rarely they occur on the contralateral side. In adults, subdural fluid accumulations after ETV have been described as a rare complication accounting for less than 2 % in most series. Peretta et al. [32] described two subdural hygromas in 355 ETV (0.6 %), Jones et al. [18] reported two subdural hygromas in 101 ETV (2 %), Schroeder et al. [35] observed three cases of subdural collections in 188 ETV (1.5 %) and de Ribaupierre et al. [5] found a higher rate of hygroma after ETV in infants and children (3 of 24 cases; 12.5 %).
Hygroma after ETV in young infants may be an under-reported phenomenon for two main reasons: patients may be asymptomatic post-operatively and delayed growth of the effusion/s after several days experience spontaneous regression in most cases. Wiewrodt et al. [43] pointed out that subdural hygromas after ETV have been reported to be far less frequent in young infants (under 3 years) than in older children. Whether there is a higher risk for the development of hygromas in the very first months of life as opposed to infants beyond age 1 year remains unclear with an age distribution analogous to ETV failure rate, decreasing later over the first 12 months [43].
A further aspect of post-operative subdural collections after ETV is gender, showing a clear predominance of boys over girls [20, 35]. The presumed pathophysiology is that CSF forces its way through the frontal cerebral tract toward the overlying subdural space as a newly created “normal” pathway. In addition, the absorptive mechanisms need time to mature in this age, so CSF naturally tries to escape through the least resistant pathway [10]. The cortical mantle may also collapse due to excessive and abrupt loss of CSF during the procedure which in turn would enlarge the space between the dura mater and the brain [32, 41, 43].
The complication is also more common in children owing to coexistent macrocephaly and to what some authors have termed “craniocerebral disproportion” in cases with long-standing significant ventricular dilatation and thin cortical mantle. In contrast, older children and adults are predisposed to subdural hygroma as the brain has been stretched for many years and no longer have the ability to expand after ETV due to the loss of the viscoelastic properties of the brain [20].
A further explanation is that ETV decreases the volume of the lateral and third ventricles due to the CSF outflow from the ventricles to the subarachnoid cisterns, but CSF absorption fails to increase as rapidly, resulting in an increase in the CSF subarachnoid space. Therefore, after long-standing obstructive hydrocephalus, the absorption pathways may not be adequate [22, 43].
In many cases, subdural collections are asymptomatic and are only diagnosed by imaging studies performed after the procedure. In symptomatic cases, clinical manifestations include nausea, vomiting, headache and decrease in the level of consciousness. Hygromas may appear several days or weeks after ventriculostomy, and this could be due to the fact that initially they are regarded to be an asymptomatic collection of CSF in the subdural space [43] (Figs. 22.4 and 22.5).
Fig. 22.4
Normal pressure hydrocephalus treated with an adjustable valve. (a) CT at diagnosis. (b–d) Emergence of a chronic subdural hematoma after a minor head injury. (e, f) CT after increasing the valve pressure
Fig. 22.5
Three-year-old child with an arachnoid cyst. (a, b) CT at diagnosis. (c) MRI (T1) at diagnosis
Most subdural hygromas after ventriculocisternostomy are asymptomatic. Clinical and radiological surveillance of patients is recommended although they resolve spontaneously. When symptomatic, hygromas can be treated with drainage of the subdural space using a burr hole or a twist drill, and only if the collection relapses should a permanent subduro-peritoneal shunt be considered [23].
As for prevention, tapping the ventricle with a thin brain needle ensures a small cortical puncture that is just large enough (not larger than necessary) to allow the insertion of the endoscope without causing displacement of the underlying brain [40, 43]. The diameter of the endoscope probably influences the occurrence of hygroma after ETV as a large cortical orifice in the presence of large ventricles may cause the passage of CSF from the ventricles to the subdural space. Some authors reported that covering the endoscopy tract with fibrin glue after completion of ETV and using haemostatic sealant agents decrease the incidence of subdural collections. Sgaramella et al. [37] recommend to rigorously control both the amount of Ringer’s solution used for flushing and the escape of CSF during ETV and to quickly close the wound as soon as the endoscope is withdrawn.
In patients with large ventricles and a thin cortical mantle, a rapid outflow of ventricular CSF during the procedure should be avoided [30]. Other authors stress that this complication can be prevented by re-expanding the ventricles with Ringer’s solution before removing the endoscope sheath from the lateral ventricle to avoid the collapse of the brain and to seal the cortical hole with a piece of gel foam [20, 26].
22.3.2 Subdural Haematomas Following Neuroendoscopic Procedures
Subdural haematoma is a rare complication of ETV with only a few cases reported up to the present day [4, 37, 39]. Though most subdural bleeding occurs on the operated side, contralateral or bilateral haematomas have also been reported [1, 37]. In a recent paper, a case of subdural haematoma after endoscopic ventriculostomy in a 21-year-old man was reported, and in the review of the literature, only another five cases with this complication were found in adults, of which two cases (33.3 %) were contralateral and one bilateral [39] (Table 22.1).
Table 22.1
Adult chronic subdural collections and endoscopic third ventriculostomy
Author | Age and sex | Aetiology of hydrocephalus | Localization | Symptomatology | Treatment |
|---|---|---|---|---|---|
Beni-Adani et al. | 20 y, M | Obstructive | Ipsilateral | Asymptomatic | Burr hole |
Sgaramella et al. | 69 y, M | Obstructive | Contralateral | Asymptomatic | Evacuated |
Kim et al. | 51 y, M | Obstructive | Bilateral | Headache | Bilateral burr hole |
Kamel et al.
Related posts: Introduction: The Use of Extrathecal CSF Shunts, Optional vs Mandatory, Unavoidable Complications
 Complications Specific to Rare Type Procedures of CSF Shunting
 Complications of Peritoneal Shunts
 Complications Related to Endoscopic Fenestration in Loculated Hydrocephalus
 Complications Related to the Type of Hydrocephalus: Normal Pressure Hydrocephalus
 Mechanical Complications of Shunts
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