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 Table of Contents  
ORIGINAL ARTICLE
Year : 2020  |  Volume : 3  |  Issue : 2  |  Page : 231-237

Symptomatic pneumocephalus following spine surgery: An institutional experience and review of literature


Spine Department, Stavya Spine Hospital and Research Institute, Ahmedabad, Gujarat, India

Date of Submission30-Jan-2019
Date of Decision26-Mar-2019
Date of Acceptance12-Aug-2019
Date of Web Publication13-Jul-2020

Correspondence Address:
Dr. Amit Jain
Stavya Spine Hospital and Research Institute, Mithakali, Ahmedabad, Gujarat.
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/isj.isj_4_19

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  Abstract 

Purpose: The objective of this study was to alert spine surgeons about possibility of pneumocephalus after spine surgery and elaborate its causes, pathophysiology, symptomatology, and management. Materials and Methods: Four patients identified to have symptomatic pneumocephalus after spinal surgery (out of total 7940 operated spine cases over a period of 5 years from January 2013 to December 2017), were included in the study. Compiled data of medical records, operative notes, in-patient treatment records, and radiological findings of these patients were evaluated. Results: All four patients had dural injury with cerebrospinal fluid (CSF) leak. Dura was repaired in two patients and was covered with fat graft in other two. Bifrontal pneumocephalus occurred in three patients while one had intraparenchymal pneumocephalus. All patients were managed conservatively with Trendelenburg position, O2 inhalation, and intravenous hydration along with supportive measures. Conclusion: Pneumocephalus is a rare but serious complication following spine surgery and should be considered in the differential diagnosis in patients presenting in postoperative period with unexplained headache, confusion, and altered sensorium. A high index of suspicion is required to make a diagnosis. Computed tomography scan or magnetic resonance imaging of the brain is required to establish the diagnosis. Most cases respond favorably to conservative treatment. However, occurrence of tension pneumocephalus is a life-threatening condition and might require urgent neurosurgical intervention.

Keywords: Cerebrospinal fluid leak, dura tear, pneumocephalus, spine surgery


How to cite this article:
Dave BR, Jain A, Degulmadi D, Krishnan A, Bang P. Symptomatic pneumocephalus following spine surgery: An institutional experience and review of literature. Indian Spine J 2020;3:231-7

How to cite this URL:
Dave BR, Jain A, Degulmadi D, Krishnan A, Bang P. Symptomatic pneumocephalus following spine surgery: An institutional experience and review of literature. Indian Spine J [serial online] 2020 [cited 2020 Aug 10];3:231-7. Available from: http://www.isjonline.com/text.asp?2020/3/2/231/289650




  Introduction Top


Pneumocephalus is air in the intracranial cavity. It could be subarachnoid, subdural, epidural, intraventricular, or intraparenchymal.[1] Its common occurrence is following skull fracture after head injury, facial injury, and post craniotomy or burr hole surgery.[1],[2],[3],[4] Occurrence of spontaneous pneumocephalus after nitrous oxide inhalation anesthesia has been reported.[5] There are few studies in the literature reporting symptomatic pneumocephalus after lumbar spine surgery but none after cervical laminectomy.[6],[7],[8],[9],[10],[11],[12],[13],[14],[15],[16],[17] As clinical presentation of such cases overlaps with common postoperative complaints, a high index of suspicion is needed for diagnosis.

We present a case series of four patients who developed symptomatic pneumocephalus after cervical or lumbar spinal surgery. The purpose of this study is to present possible causes, pathophysiology, symptomatology, and management concepts with literature review about postspinal surgery pneumocephalus.


  Materials and Methods Top


Out of 7940 cervical and lumbar spine surgery cases operated in our institute between January 2013 and December 2017, four cases were identified to have postoperative pneumocephalus and were included in this study. Compiled data of medical records of these patients was evaluated. The preoperative diagnosis was cervical with lumbar stenosis, intradural tumor, lumbar disc herniation, and pseudomeningocele with multilevel lumbar stenosis. The surgical interventions undertaken were multilevel laminectomy, intradural tumor excision, discectomy, and multilevel lumbar fusion surgery as discussed below.


  Results Top


Case 1

A 60-year-old woman presented with a history of weakness in both lower limbs, difficulty in walking, and imbalance for seven days. She was previously operated elsewhere for dorsal laminectomy (D1-D6) six years ago. On examination, spastic paraparesis in lower limbs and bilateral hand grip weakness were noted. Magnetic resonance imaging (MRI) scan showed ossified posterior longitudinal ligament with C2-C6 stenosis and hypertrophied ligamentum flavum with D9-10 to L4-5 stenosis. She underwent C2-C6 and D9-L4 laminectomy in prone position by two surgical teams. Head high position was given intraoperatively to reduce venous congestion and intraocular pressure. An irreparable dural tear occurred in the course of cervical laminectomy due to significant adhesions. Fat graft was used to cover the defect and a positive pressure suction drain was placed. Immediate routine postoperative screening MRI showed adequate decompression and cerebrospinal fluid (CSF) collection at cervical level [Figure 1]A–C.
Figure 1: Case 1. (A) Preoperative T2 sagittal cuts showing ossified posterior longitudinal ligament with C2-C6 stenosis and hypertrophied ligamentum flavum with D9-10 to L4-5 stenosis. (B), (C) Postoperative T2 sagittal cut with laminectomy status and cerebrospinal fluid collection at cervical region. (D) Magnetic resonance imaging of brain showing subdural pneumocephalus at bifrontal region with separation of tips of frontal lobes (Mount Fuji sign)

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On postoperative day 1 (after 24 h), it was noticed that the patient had become drowsy with altered sensorium and complained of increasing frontal headache and nausea. Neurology was intact. Vitals and blood parameters were normal. MRI brain performed on same day revealed subdural pneumocephalus at bifrontal region with separation of tips of frontal lobes (Mount Fuji sign) [Figure 1D]. No signs of infarct or intraparenchymal hemorrhage were noted. She was managed with Trendelenburg (30° head low) position, intravenous fluids, 100% O2 inhalation, antiemetics, and analgesics. She showed signs of clinical improvement two days after initiation of treatment with complete resolution of symptoms over a period of eight days. Suction drain was removed on eighth postoperative day once the collection was less than 50 mL in 24 h. No follow-up MRI or computed tomography (CT) of the brain was performed as the patient improved clinically. She was discharged on 12th postoperative day with partial recovery in neurological status.

Case 2

A 30-year-old man presented with weakness in left lower limb and difficulty in walking for two months. On examination, he was found to have deformity at dorsolumbar spine with grade 0 power in left ankle dorsiflexors and plantar flexors. Sensation was decreased in left L4, L5, and S1 dermatomes, and ankle reflex was absent. Neurology on right side was normal.

MRI of spine showed intradural dermoid cyst from D12 to L4 level, and diastematomyelia with bony bar at L3 level was noted on CT scan [Figure 2]A and B. The patient underwent durotomy with excision of dermoid cyst and the bony bar. Dura was repaired with continuous 4-0 silk. A suction drain with positive pressure was placed subfascially. Postoperatively, after 24 h, patient complained of severe headache, vomiting, and lethargy. His blood parameters and vitals were normal and neurology was intact. Routine postoperative MRI with screening of brain revealed pneumocephalus with scattered air in bifrontal, parafalcine, and right temporal region, and pneumorrhachis at lumbar level [Figure 2]C and D. The patient was managed with 30° Trendelenburg position, intravenous fluids, O2 inhalation, and supportive treatment. He started showing signs of clinical improvement within 24 h of starting conservative treatment with complete clinical recovery in six days. No follow-up MRI was performed. He was discharged on ninth postoperative day. At 6-month follow-up, patient was neurologically improving.
Figure 2: Case 2. (A) T2 magnetic resonance imaging L-S spine showing intradural dermoid cyst from D12 to L4 level. (B) Computed tomography cut showing diastematomyelia with bony bar at L3 level. (C) Postoperative T2 magnetic resonance imaging showing pneumorrhachis at L3-4 level. (D) Magnetic resonance imaging brain showing pneumocephalus with scattered air in bifrontal, parafalcine, and right temporal region (White arrow represents pneumocephalus in parafalcine region)

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Case 3

A 48-year-old woman presented with left lower limb radicular pain for five days and difficulty in walking. Complaints started after an episode of lifting heavy weight. On examination, straight leg raise test was positive. Left ankle dorsiflexors power was grade 0, and sensation was decreased in left L4 dermatome. MRI showed big caudally migrated, extruded axillary disc at L3-4 level [Figure 3]A and B. She was planned for L4 laminectomy and discectomy. During removal of axillary disc fragment, a small dural puncture occurred at ventrolateral aspect of dura with discectomy forceps, which was not amenable to repair. Fat graft was placed over the dura and closure performed in layers over a positive pressure drain. On second postoperative day (after 48 h), the patient complained of severe frontal headache, which increased with upright position, nausea, and dizziness. MRI of brain performed along with routine postoperative lumbar spine screening revealed pneumocephalus in bifrontal region [Figure 3]C. The patient was advised head low position. O2 inhalation, intravenous fluids, and other symptomatic management were followed. Her clinical condition started improving after 24 h and she became symptom free in eight days. Drain was removed on fifth postoperative day once the collection was less than 50 mL over 24 h.
Figure 3: Case 3. (A), (B) Magnetic resonance imaging L-S spine showing sequestrated L3-4 disc. (C) Magnetic resonance imaging brain showing bifrontal pneumocephalus

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Case 4

A 56-year-old woman presented with complaints of backache and bilateral lower limbs radicular pain on walking for last six months. She had undergone spinal surgery nine years back for similar complaints and was symptom free after surgery for approximately eight years. MRI of lumbar spine revealed L3 and L4 laminectomy along with a pseudomeningocele, which could have been caused because of unrepaired dural defect during previous surgery [Figure 4]A and B. She underwent L2-L5 instrumented spinal fusion with L2 and L5 laminectomy and lateral recess decompression. Pseudomeningocele sac was excised; previous dura defect was identified and repaired with fascia graft cover. A positive pressure subfascial suction drain was placed.
Figure 4: Case 4. (A), (B) Preoperative T2 magnetic resonance imaging L-S spine showing post-laminectomy pseudomeningocele. (C) Postoperative T2 cuts showing L2 to L5 instrumented spinal fusion and pneumorrhachis at L3-4 level. (D) Magnetic resonance imaging of brain showing bifrontoparietal pneumocephalus with separation of tips of frontal lobes (Mount Fuji sign)

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Postoperatively, bed rest was advised. She complained of some heaviness in head, which was expected after CSF loss. After 48 h of surgery, she complained of severe headache, photophobia, and nausea. All vital signs were normal and neurology was intact. On the basis of our experience with previous cases, she was immediately given Trendelenburg position (30° head low) and was managed with intravenous fluids, 100% O2 inhalation, and supportive treatment. Screening MRI performed next morning showed bifrontoparietal pneumocephalus with separation of tips of frontal lobes (Mount Fuji sign) and pneumorrhachis at lumbar spine region [Figure 4]C and D. Her symptoms began resolving after 36 h with complete recovery in next seven days. Mobilization was started on eighth postoperative day and she was discharged on 11th postoperative day.


  Discussion Top


Pneumocephalus is commonly reported after skull or facial fractures and trace amount of air is seen in almost all postoperative scans after craniotomy, burr hole surgery, or skull base surgeries.[18] Occurrence of pneumocephalus after lumbar puncture cervical or lumbar epidural injections is seen following entry of air into intrathecal space.[19] Spontaneous pneumocephalus after nitrous oxide inhalation anesthesia was reported by Theilen et al.[5] Pneumocephalus after spinal surgery is a rare but serious complication. Very few isolated case reports are found in literature [Table 1]. In this study, we present four cases of symptomatic pneumocephalus after spinal surgery that also includes, to best of our knowledge, the first case report of symptomatic pneumocephalus after posterior cervical laminectomy [Table 2].
Table 1: Review of Literature

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Table 2: Findings in present study

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Spine surgery is associated with myriad of complications including wrong level surgery, missed level, nerve root injury, and dural tear with CSF leak. Dural injury during spinal surgery is seen to be associated with pneumocephalus and pneumorrhachis (air in the spinal canal). However Ayberk et al.[11] reported a case without any recognized perioperative dural injury. Placement of vacuum drainage in the presence of CSF leak also predisposes to increase in the occurrence of pneumocephalus after spine surgery as it allows further ingress of air into subarachnoid space via a defect in dura.[6],[7] In our case series, two of the four patients had dural tear with CSF leak intraoperatively, which was repaired using 4-0 silk. In the other two patients, dural tear was covered with fat graft. All the patients had subfascial positive pressure vacuum drainage that was removed as an institutional protocol, when the collection was less than 50 mL over 24 h.

Two theories have been proposed in the literature to describe the pathophysiology of pneumocephalus after spine surgery: the ball-valve mechanism[6],[20] and the inverted bottle mechanism.[3] The ball-valve mechanism hypothesizes that air enters the subarachnoid space through a rent in dura, which acts as one-sided valve and prevents exit of air leading to pneumocephalus. In the second theory, the inverted bottle mechanism, it is postulated that as CSF flows out of the subarachnoid space through a dural tear, negative pressure is created within the subarachnoid space, leading to entry of air in the space and then in cranial cavity, balancing the pressure differential. The presence of suction drain may also contribute to pneumocephalus via inverted bottle mechanism.

Progressively increasing, severe headache is the first and most common presenting symptom. It may be associated with nausea, vomiting, photophobia, somnolence, dizziness, or altered sensorium.[1] These nonspecific symptoms are usually considered insignificant in the postoperative period. It is important to identify the headache caused due to CSF leak and that due to pneumocephalus. CSF leak causes negative intracranial pressure and might lead to sagging of brain. This causes occipital headache in recumbent position with a feeling of pulling pain in the neck. In pneumocephalus, the presence of air irritates the meninges. Progressively increasing severe headache is usually seen in bifrontal area, as accumulation of air is more common in that area. It is extremely sensitive to slightest movement.[21]

Onset of these symptoms is usually reported between 24 and 48 h after spine surgery. Differential diagnosis may include electrolyte imbalance, uremia, metabolic acidosis, meningitis and subdural haematoma. In clinical practice, it is vital to identify the possibility of tension pneumocephalus, which may present with severe headache, restlessness, seizures, deterioration in consciousness, and increasing neurological deficits. Tension pneumocephalus refers to collection of air in the intracranial cavity under pressure causing mass effect, possibly secondary to a ball-valve mechanism.[3] Intracranial hemorrhage in the form of subdural or cerebellar hemorrhage has been reported by few isolated case studies secondary to CSF leak after spine surgery.[22] Intracranial hypotension due to CSF leak is identified as a potential source of subdural hematoma as a result of traction on cerebral veins. Signs and symptoms in such cases include postural headache, neck stiffness, and occasionally neurological deterioration. Most of these cases are managed conservatively, however some require prompt evacuation.

CT brain is investigation of choice for diagnosis of pneumocephalus and can diagnose as little as 0.55 mL of air.[23] MRI brain can also be used for diagnosis.[6] The presence of air in epidural, subdural, subarachnoid space, parenchyma, or ventricles is indicative of pneumocephalus. As the patient usually rests in supine position, accumulation of air at frontal region is the most common radiological finding in CT or MRI brain and correlates with symptoms of frontal headache, which is a common presenting feature. Tension pneumocephalus may present with widened interhemispheric space between the tips of frontal lobes (Mount Fuji sign) or with midline shift of brain.[24] X-ray skull usually detects more than 2 mL of air and is not used as a routine diagnostic tool.[14] Repeat scans show resolution or increase in intracranial air but there are no guidelines in literature suggesting when the scans should be repeated. In this study, we did not repeat scans, as all our patients responded favorably to conservative management.

Management is generally conservative with rest, intravenous hyperhydration, 100% oxygen inhalation, and supportive measures. There is no general consensus in literature regarding postoperative positioning of patients, as majority advocate Trendelenburg position and a few reverse Trendelenburg.[12] In our study, we have placed the patients in Trendelenburg position (15°–30° head low) as we believe that it causes air to migrate up from cranial to caudal position, that is from brain toward the spinal canal and thus relieving intracranial pressure. Administration of 100% oxygen reduces the partial pressure of nitrogen in blood. The difference created in concentration gradient of nitrogen between blood and intracranial air causes nitrogen to diffuse into blood stream. Therefore oxygen hastens the rate of absorption of intracranial air (nitrogen) into blood.[21] Improvement generally starts in 24–48 h with complete resolution of symptoms in 1–3 weeks. Of special mention is tension pneumocephalus, which might require emergency decompressive procedures to relieve intracranial pressure.[4]


  Conclusion Top


Pneumocephalus is a rare but potentially serious complication of spine surgery. A high index of suspicion is required to make a diagnosis in patients with dural tear and CSF leak, developing unexplained postoperative severe headache and altered sensorium. CT scan or MRI brain is required to establish the diagnosis. Though conservative measures suffice, emergency decompression may be needed in cases of tension pneumocephalus.

Acknowledgement

We sincerely thank Dr. Preety Krishnan for helping us in interpretation of radiological findings.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Theilen HJ, Heller AR, Litz RJ. Nitrous oxide-induced tension pneumocephalus after thoracic spinal cord surgery: A case report. J Neurosurg Anesthesiol 2008;20:211-2.  Back to cited text no. 5
    
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24.
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