45 Chronic Subdural Hematoma

Remi Nader

Fig. 45.1 (A,B) Computed tomography scan of the brain without contrast.

Clinical Presentation

A 70-year-old woman with end-stage Alzheimer’s disease, diabetes mellitus, nursing home bound, is brought to the ER for a 3-day episode of increasing confusion, agitation, and inappropriate behavior.

The patient is confused at baseline, however, she was noted to be combative and refusing her care as well as voicing aloud her request to leave the nursing home and to go home, which is unusual behavior for her.

She is a poor historian, but she does report having had frequent falls in the near past.

Physical examination reveals a left-sided pronator drift and confusion. The remainder of the examination is normal.

Computed tomography (CT) scan is obtained and shown in Fig. 45.1.

Questions

Interpret the CT scan.

What other questions or information would you like to obtain to further plan your management?

What further studies or investigations would you like to obtain?

What would you tell the family, next of kin, or caregiver?

The patient is on no anticoagulant or antiinflammatory medications. Her laboratory results including complete blood count, electrolytes, and coagulation profile are within normal limits. You had a discussion with the family about the treatment options and they opted for surgery.

How would you approach this case surgically? Describe all the steps of surgery including positioning, incision, bone opening, evacuation, and closure.

Preoperatively, as you plan the surgery, she develops hyponatremia with sodium of 118, and she becomes more lethargic. What are some causes of hyponatremia and which is the most likely in this case?

How would you manage this problem?

She does well from bilateral burr-hole evacuation of subdural hematomas, and is discharged home. However, she comes back 3 weeks later to your clinic. She now has some purulent discharge from the right posterior incision. She is somewhat somnolent and has a left hemiparesis slightly worse than the one she had immediately postoperatively.

What is your course of action now?

A follow-up CT scan and subsequently a magnetic resonance imaging (MRI) scan are obtained (Fig. 45.2). Interpret the studies and provide a differential diagnosis.
What is your management plan?

Fig. 45.2 (A) Computed tomography scan with contrast and (B) magnetic resonance imaging fluid-attenuated inversion-recovery axial image without contrast, and T1-weighted images with contrast, (C) axial and (D) coronal.

Answers

Interpret the CT scan.

CT scan of the brain reveals bilateral subdural hematomas which are mainly chronic with a very small subacute component on the right side.
The right subdural hematoma is close to 1.5 cm in thickness. The left subdural hematoma is ~1.3 cm in thickness. They are both mainly along the convexity in the frontal and somewhat parietal area.
There is some diffuse brain atrophy in both frontal lobes consistent with advanced Alzheimer’s disease.
There also appears to be no midline shift, no obvious mass effect, and no edema. The basal cisterns are wide open.
There might be some effacement in the sulci along the cortical surface in the frontal lobes.

What other questions or information would you like to obtain to further plan your management?

Obtain current medication history, especially whether or not she is on anticoagulants.
Determine if there is a living will or a durable power of attorney. If so, determine the patient’s wishes in a situation where lifesaving measures are needed.

What further studies or investigations would you like to obtain?

Laboratory tests: complete blood count, electrolytes, coagulation profile, type and screen
Other imaging: MRI – unlikely to change your management in this case
If surgical intervention is contemplated, then medical clearance may be needed (electrocardiogram [EKG], chest x-ray, cardiac echography, etc.)

What would you tell the family, next of kin, or caregiver?

The patient has fluid collections on the surface of her brain, and that these are likely due to old hemorrhages.

It is not clear whether or not these fluid collections are causing a lot of pressure on her brain.

She also has brain atrophy due to Alzheimer’s disease.

She may possibly benefit from evacuation of the fluid collections.1

However, the caregiver needs to be aware that evacuation may also not help as she may be having progressive dementia due to Alzheimer’s and she may also have complications from the surgery.

Inform the caregiver of all the potential surgical complications. These include, but are not limited to pain; bleeding; infection; failure to treat presenting condition; need for further surgeries or procedures in the future; reaccumulation of the fluid collections damage to adjacent blood vessels, nerves, and tissues; additional loss of brain function including memory, stroke, changes in vision, deafness, inability to smell, coordination loss, seizures, cerebrospinal fluid leak; weakness; impaired muscle function; numbness; paralysis; death.2–4
How would you approach this case surgically? Describe all the steps of surgery including positioning, incision, bone opening, evacuation, and closure.
- One operative option consists of bilateral burr hole evacuation of the subdural hematoma, with two burr holes placed on each side.^5–9
- Preoperative preparation includes
  - Preoperative antibiotics, cefazolin 1 g intravenously (IV) every 8 hours
  - Preoperative seizure prophylaxis with phenytoin, loading dose of 1 g IV over 1 hour, followed by a maintenance dose of 100 mg every 8 hours
  - Positioning is supine with head of bed slightly elevated
  - Anesthesia preferably conscious sedation, or general endotracheal if the patient will tolerate it (i.e., no cardiac or pulmonary risk factors)
- Surgical steps include
  - Hair clipping and mark incisions along the convexity in-line with each other such that if the need for a bone flap arises it will suffice to connect both incisions.
  - The incisions should be ~5–6 cm away from the midline; one along the parietal boss and one just behind the hair line anteriorly – both ~3 cm in length.
  - Start by opening the right side as this is the symptomatic side.
  - Open skin, galea, and periosteum with a no. 10 blade; expose the skull and perform a burr hole with a pneumatic drill, ~2.5 cm in diameter.
  - Wax the bone edges and cauterize the dura.
  - Open the dura in cruciate fashion, then drain the blood.
  - Irrigate both burr holes profusely with normal saline until the drainage becomes clear.
  - One may place a red rubber catheter in the burr hole subdurally and further irrigate to dislodge any pockets of blood that are harder to access.
  - Closure is completed by placing a piece of Gelfoam (Pfizer, Inc., New York, NY) on top of the burr hole, close the skin and galea with 3–0 Vicryl (Ethicon, Somerville, NJ) and staples.
  - One may leave a small drain in the subgaleal space.
- The patient is kept with the head of the bed flat postoperatively.¹⁰
Preoperatively, as you plan the surgery, she develops hyponatremia with sodium of 118, and she becomes more lethargic. What are some causes of hyponatremia and which is the most likely in this case?
- Causes of hyponatremia are listed below.
- Hypovolemic hyponatremia: sodium and free water loss with inappropriately hypotonic fluid replacement
  - Cerebral salt-wasting syndrome: traumatic brain injury, aneurysmal subarachnoid hemorrhage, subdural hematoma, and postcraniotomy – this is the most likely cause in this case
  - Gastrointestinal losses such as vomiting or diarrhea
  - Excessive sweating
  - Third spacing of fluids (peritonitis, pancreatitis, burns)
  - Acute or chronic renal insufficiency
  - Prolonged exercise in a hot environment
- Euvolemic hyponatremia: normal sodium stores and total body excess free water
  - Psychogenic polydipsia
  - Hypotonic intravenous (i.v.) or irrigation fluids postoperatively
- Hypervolemic hyponatremia: inappropriate increase in sodium stores
  - Hepatic cirrhosis
  - Congestive heart failure
  - Nephrotic syndrome
  - Hypothyroidism
  - Cortisol deficiency
  - Syndrome of inappropriate antidiuretic hormone (SIADH)¹¹
  - Medications: acetazolamide, thiazide diuretics, angiotensin-converting enzyme inhibitors, carbamazepine, gabapentin, haloperidol, heparin, ketorolac, loop diuretics, nimodipine, opiates, proton pump inhibitors, selective serotonin reuptake inhibitors^11–13
How would you manage this problem?
- Ensure that the patient is stabilized first: secure airway, breathing, circulation (ABCs of trauma), place on oxygen transfer to intensive care unit (ICU), obtain i.v. access with large bore i.v., place a Foley catheter
- Obtain laboratory studies to determine which type of hyponatremia including
  - Serum and urine sodium and osmolalities, and urine specific gravity
  - Serum electrolytes
  - Thyroid function studies
  - Adrenal function studies
- In this case, the most likely cause is hypovolemic hyponatremia possibly from the subdural hematoma.
- If the symptoms are mild to moderate one may treat with isotonic saline.
- Monitoring of serum sodium levels needs to be done frequently to ensure that the serum sodium increases to no greater than 0.5 mEq/L/hour or 12 mEq/L/day.
- Hypertonic saline (3%) may be used as an alternative if normal saline alone is not adequate enough to correct the problem. When using this solution, care should be taken to administer it slowly (20 to 50 cc/hour drip) and frequent checks on serum sodium is required (every 2–4 hours).
- Evacuation of the subdural hematoma may resolve the hyponatremia (it did in this case).12,13
What is your course of action now?
- Urgent ICU admission
- Laboratory studies: complete blood count, electrolytes, coagulation profile, type and screen, blood, urine, sputum cultures, and culture discharge from wound
- Obtain imaging studies: CT and MRI with and without contrast
- May elect to wait until the cultures are sent intra-operatively before starting any broad spectrum antibiotics.
- Antibiotics suggested:
  - Vancomycin 1 g i.v. every 12 hours, cefepime 2 g i.v. every 12 hours, and metronidazole 500 mg i.v. every 8 hours
  - Gentamycin 600 mg i.v. every 8 hours may be used instead of cefepime if the patient is allergic to penicillin.
  - Antibiotic changes are performed as culture and sensitivity results are obtained.
A follow-up CT scan and subsequently an MRI are obtained (Fig. 45.2). Interpret the studies and provide a differential diagnosis.
- CT scan with contrast shows some reaccumulation of fluid bilaterally. The fluid collection on the right side is partly hyperdense or enhancing, which is suggestive of acute blood or possible empyema with peripheral enhancement.
- On MRI, the subdural fluid is consistent with blood of different ages and it is seen bilaterally. On the right side there is some enhancement surrounding the subdural fluid which is possibly suggestive of infection.
- The right subdural fluid appears to be iso- to hyperintense on T1-weighted and hyperintense on T2-weighted or fluid-attenuated inversion-recovery (FLAIR) MRIs, which, if it is blood, is likely subacute to chronic (3 weeks old).
- The differential diagnosis includes
  - Reaccumulation of subdural hematoma
  - Subdural empyema
  - Subdural hygroma
What is your management plan?
- Urgent surgical evacuation via burr hole reexploration on the right side.^14–16
- The exposure should be prepared in the event that a craniotomy is needed.
- Subdural fluid needs to be sent for culture as soon as possible, after which the antibiotics are initiated.
- Incision and sharp debridement of the posterior scalp wound is needed with irrigation and antibiotics and saline solution.
- A drain can be left in the subgaleal space.
- Wound closure can be done in a single layer with 2–0 Prolene (Ethicon, Somerville, NJ) vertical mattress interrupted sutures to promote better healing of infected or granulating tissues.