"Rabbit Ear" scalp deformity caused by massive subdural effusion in infant following bilateral burr-hole drainage.

Subdural effusion (SDE) in an infant is a rare clinical scenario, which may be secondary to a variety of etiologies. Massive SDE is an extremely rare complication of head injury. It usually runs a self-limiting course. Though neurosurgical intervention is occasionally needed, different methods of surgical procedure for management includes burr-hole alone, burr-holes with subdural drain placement, twist drill craniotomy with drain and even craniotomy. The authors report a rare case of progressive massive SDE, which despite bilateral burr-hole placement and drainage failed and presented with visual deterioration and massive bulge of scalp at burr-hole sites producing rabbit ear sign in a 10 month old infant. Ultimately cystoperitoneal shunt was carried out in a desperate attempt to prevent impending rupture of scalp sutures at sites of previous burr-hole placement. Astonishingly not only complete resolution of hygroma, but visual recovery also took place. Patient is doing well at 6 months following shunt with regaining normal vision and appropriate developmental milestones. A magnetic resonance imaging scan of brain at last follow-up revealed mild ventriculomegaly with subduro-peritoneal shunt in situ and rest of brain was unremarkable. Such cases have not been reported in literature until date.

Introduction

Persistent accumulation of fluid in the subdural space may be either hygroma or hematoma. It is encountered commonly in infants, usually secondary to head injury; other causes are leptomeningeal infection, arachnoid cyst or post ventriculo-peritoneal shunt.[123] These collections evolve following acute onset hematoma or breach of the arachnoid usually precipitated by blunt force trauma, which may occur following accident or non-accidental origin.[1245] Subdural effusion (SDE) may show spontaneous resolution or enlarge with passage of time. It may clinically present with rapid enlargement of head size, focal symptoms caused by compression over adjoining brain parenchyma or in progressively enlarging condition can produce global neurological deficits. Raised and progressively worsening intracranial pressure in our case led to visual deterioration, tense fontanelle and progressive bulging of scalp due to ongoing accumulation of subgaleal collection with impending rupture of scalp wound at burr-hole site, which required subduro-peritoneal shunt.

Case Report

This 10-month-old male infant, presented at our neurosurgical emergency services with a history of depressed sensorium for 2 days. This followed a road traffic accident 10 days ago in which he was sitting at the rear seat of car and was the sole survivor. On physical examination, his pulse rate was 158/min and blood pressure 68/40 mm Hg. On neurological assessment at admission, he was arousable, moving limbs spontaneously with good cry. His anterior fontanelle was tense. Pupils were mid dilated and non-reacting to light. Hematological and biochemistry profiles were within the normal limits. Computerized tomography (CT) scan of the head done immediately after accident revealed presence of thin subdural hygroma in both frontoparietal regions with compression of adjacent brain [Figure 1]. Ophthalmologist evaluation for vision showed doubtful presence of vision. He was being managed with cerebral decongestant with regular visual assessment and monitoring under ophthalmologist. Repeat CT scan and magnetic resonance imaging (MRI) done after 10 days, following depression of sensorium revealed enlargement of bilateral SDE [Figure 2] and fundoscopy revealed presence of bilateral papilledema. Patient was shifted to operating room for emergency evacuation of SDE. Right parietal and left parietal burr-holes were placed with drainage of subdural hygroma; the fluid collection was xanthochromic and under raised pressure. The post-operative period was uneventful except rapid bulging of scalp wound at burr-hole site seen bilaterally. He was put on acetazolamide and furosemide with spironolactone for 2 weeks. Despite these, scalp swelling continued to increase rapidly on both burr-hole sites with impending rupture of wound at burr-hole site. The bulging of scalp mimicked bilateral ‘rabbit ear’ appearance [Figure 3b]. CT scan showed the presence of massive SDE causing mass effect [Figure 3a]. So he was again taken to operation theatre and under general anesthesia a right sided subduro-peritoneal shunt was carried out. Subdural fluid sample was sent for cytopathology, biochemistry and aerobic, anaerobic, fungal and mycobacterial tuberculosis culture. In the post-operative period, subduro-peritoneal shunt was working well with complete resolution of subdural fluid collection. He was discharged on fifth post-operative day following shunt surgery.

Figure 1

Initial non-contrast computerized tomography head at time of injury showing thin bilateral fronto-parietal subdural hygroma with effaced cerebral sulci and gyri

Figure 2

Repeat non-contrast computerized tomography head (a-c) after 10 days showing marked increase in bilateral subdural collection with mass effect. Magnetic resonance imaging T1WI (d) and T2WI (e and f) showing similar findings

Figure 3

(a) Non-contrast computerized tomography head done 20 days following burr-hole drainage showing bilateral tense subdural collection of cerebrospinal fluid density fluid; (b) clinical photograph of patient at the same time, (c) magnetic resonance imaging T2WI at 6 months follow-up showing complete resolution of subdural collection with mild ventriculomegaly; and (d) clinical photograph of patient showing complete subsidence of scalp swelling with reversal of sunset sign compared to (b)

At the last follow-up 6 months after surgery, he regained significant visual recovery and MRI carried out at follow-up showed a mild hydrocephalus with no residual subdural collection [Figure 3c–d]. He was regularly followed-up in pediatrics and the observed developmental milestones were corresponding to the child's age.

Discussion

Subdural collection in infants is a rare clinical scenario, which may be caused by cranial trauma, infection of meninges or skull, or as a complication of ventricular shunting with over drainage.[123] The natural course of subdural hygroma can be either spontaneous resolution associated with subsidence of mass effect or can have slow progression and very rarely rapid progression as occurred in the current case. Postulation for increase in size of hygroma includes arachnoid rupture with escape of cerebrospinal fluid or transudation causing mass effect. This may promote rupture of bridging veins leading to bleeding in subdural space, with consequent formation of neo-membrane and repeated micro-hemorrhages into membrane can cause further expansion and compression causing focal or global neurological manifestation.[24]

Miyake et al. reported, SDE can be categorized into four distinct clinical phases viz. (i) Arachnoid rupture (ii) Inner membrane formation stage (iii) Inner as well as outer membrane formation stage and (iv) Subdural hematoma or hygroma.[6] He further suggested appropriate treatment modality for each stage and advocated fontanelle tapping up to first and second stages, continuous external drainage for third stage and last stage needing burr-hole aspiration and irrigation.[6] Various risk factors incriminated for recurrence following surgical intervention include a mixed-density subdural hematoma, presence of subdural hematoma bilaterally, associated post-operative pneumocephalus, poor Glasgow Outcome Scale score and a smaller subdural drain output.[78]

Various treatment modalities have been advocated including fontanelle tapping, burr-hole craniotomy as a standalone procedure, burr-holes with placement of subdural drains, twist drill craniotomy with drain placement and formal craniotomy and have been extensively evaluated.[91011] Fontanelle tapping can be used for every stage and rarely massive bleeding is encountered if small needle is utilized for punctures. Continuous external drainage involves a risk of infection.[6] Implantation of an Ommaya reservoir and endoscopic observation along with burr hole irrigation are very useful methods of treatment for SDE. Miyake et al. discourages use of subduro-peritoneal shunt and it cannot be recommended for the treatment of SDE in most cases.[6] Subdural shunts have an inherent long-term potential morbidity.[5] Few cases may develop subarachnoid to subdural collection, which may be unrecognized and cause dependence on shunt. A second surgery may be required for its removal if it is not needed anymore.[5] Klimo et al.[5] advocates most desirable procedure would be one that has the greatest chance of definitively treating the SDE as a single surgery with low risk of complications and without placing a shunt. Contrary to this, in our case despite burr-hole placement and conservative treatment becoming ineffective, the patient developed progressive subdural hygroma under pressure with visual deterioration, which was managed successfully with placement of a subduro-peritoneal shunt. The authors recommend that subduro-peritoneal shunt still has a role in management of such cases especially associated with raised intracranial pressure and its sequelae (depression of sensorium and visual deterioration), which showed complete resolution of SDE as well as amelioration of raised pressure leading to functional recovery of vision.