Sample Inpatient Chart 3 OP report

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OPERATIVE REPORT

Pre-Op Diagnosis Codes:

   * EPIDERMOID CYST, BRAIN

 

Post-Op Diagnosis Codes:

   * EPIDERMOID CYST, BRAIN

 

Procedure(s) (LRB):

CRANIOTOMY POSTERIOR FOSSA CP ANGLE TUMOR (Left)

Anesthesia Type:

General Anesthesia

 

Findings:

     Classic epidermoid tumor medial to cranial nerves 7-11 crossing the midline ventral to the brainstem.

Electrophysiologic monitoring parameters ended at baseline with exception of decreased left CN 12 MEP despite intermittent fluctuations in BAER and cranial nerve EMG

  

Procedure in Detail:

The patient was brought to the operating room where satisfactory general endotracheal anesthesia was induced.  Intravenous antibiotics, steroids and mannitol were administered.  The table was rotated 90 degrees.  The patient was positioned in the right lateral decubitus position on a beanbag with an axillary roll in place.  The beanbag was deflated to secure the patient in position.  Care was taken to pad all contact points.  The head was placed in Mayfield 3-point pin fixation and rotated to bring the left suboccipital region uppermost in the field.  The ipsilateral shoulder was taped caudally. 

 

Electrophysiologic monitoring leads were placed to monitor parameters including cranial nerve MEP and EMG as well as BAER.

 

The left suboccipital region was then prepped and draped in the usual sterile fashion.

 

A longitudinal incision was marked out just behind the left ear and infiltrated with 10 mL of 1/4% Marcaine with epinephrine.  The incision was made down to the underlying soft tissue.  Hemostasis was obtained with electrocautery and a self-retaining retractor was introduced into the wound.  The incision was deepened in line with the skin using the Bovie and a subperiosteal dissection was carried out so as to expose the retromastoid region.

 

Next, a bur hole was placed over the asterion and the craniotome was used to excise a retromastoid bone flap so as to expose the edges of the transverse and sigmoid sinuses.  The area of the mastoid air cells was drilled out to expose the edge of the sigmoid sinus.  The air cells were packed with free muscle graft, then copiously waxed.

 

Next, after epidural hemostasis was secured with thrombin-soaked Gelfoam, the dura was sharply opened in V-shaped fashion and dural edges were flapped inferiorly and laterally with sutures.  This revealed the lateral aspect of the cerebellum.  CSF was aspirated to facilitate cerebellar slackening.

 

The operating microscope was draped and brought into play.  The Greenberg retractor system was used to gently elevate the cerebellar hemisphere.  Under high-power vision, the cisterna magna was opened to drain additional CSF.  Working superiorly, the lower cranial nerves were skeletonized using sharp technique.  This revealed a pearly white tumor medial to the nerves that appeared to be compressing the 7/8 nerve complex laterally.  Working between the neural corridors, the tumor was dissected away from the cranial nerves and vascular structures and suctioned free incrementally.  Tumor was rolled away from the brainstem as well as the medial aspect of the 7/8th nerve complex.  Facial EMG activity and decrease in ipsilateral BAER was treated with instillation of papaverine with noted improvement in parameters.

 

Tumor was dissected away from the brainstem surface working in a cephalad direction, freeing cranial nerve 6 and then 5 along their respective lengths.  The 4th nerve was not involved with tumor.

 

Next, additional tumor was delivered from the ventral aspect of the brainstem across the midline.  The basilar artery was freed of tumor.  In this vicinity, the epidermoid membrane was noted to be much more fibrous and tenacious, precluding safe gross total resection..

 

At this point, cranial nerves 4-12 were freed of tumor and anatomically preserved.  All parameters were at baseline at this point except for diminished 12th nerve MEP.

 

The retractor was removed from the field.  Copious irrigation was carried out. 

 

The dura was closed with running 4-0 Surgilon.  The dural repair was bolstered by a thin layer of Duraseal, then an on-lay Duragen graft and a thicker coating of Duraseal.  The microscope was removed from the field.

 

After copious antibiotic irrigation was carried out, the bone flap was returned to the field and rigidly fixated with a titanium plating system.  The deep muscles were infiltrated with an additional 30 mL of 1/4% Marcaine.  After hemostasis was obtained and copious antibiotic irrigation carried out, the muscles and fascia were closed with layers of interrupted 0 Vicryl sutures.  The subcutaneous layer was closed with inverted interrupted 3-0 sutures and the skin edges were approximated with a running 4-0 Caprosyn suture.  An Exofin glue dressing was applied.

 

The patient was then undraped and removed from the Mayfield head holder.  The patient was returned to the supine position, allowed to awaken and extubated.  The patient was then transported to the recovery room in good condition.

  

Estimated Blood Loss:

   50 ml

 

Fluids:

   Crystalloid: 2000 ml

 

Drains:

  none

  

NEUROMONITORING NOTE

DIAGNOSIS:  Cerebellopontine angle tumor 

SURGICAL PROCEDURE: Left suboccipital craniotomy approach for tumor

 

INTERPRETATION:

Intraoperative monitoring of somatosensory evoked potentials (SEPs) after bilateral independent ulnar and posterior tibial nerve stimulation; transcranial electrical motor evoked potentials (MEPs); brainstem auditory evoked responses (BAERs), after bilateral independent ear stimulation, using ear inserts; as well as spontaneous EMG activity of bilateral cranial nerves (CN) V, VII, IX, X, XI, and XII was performed.  Sterile subdermal needles were placed in the bilateral masseter, orbicularis oculi, orbicularis oris, mentalis, trapezius, and tongue muscles for CN V, VII, XI, and XII monitoring. Hook wires were placed in stylopharyngeus muscle for monitoring of CN IX. NIM endotracheal tube was used to monitor CN X. MEPs were recorded using sterile subdermal electrodes in the bilateral first dorsal interosseous muscle.

 Baseline cerebral (N20-P23, P37-N45) SEPs were obtained after induction of anesthesia and prior to first incision, and revealed reproducible waveforms from bilateral upper and lower extremities.  Using transcranial electrical stimulation from subdermal electrodes on the scalp at C3 to C4 and with a threshold of 100 volts (duration of 0.05 ms, an ISI of 1 and a train of 6 stimuli), reproducible MEPs were elicited from right hand, and increasing the stimulation to 160V, right upper, lower, and CN XI MEPs were obtained. A left hand MEP was elicited at 100 V using reverse polarity, and increasing the stimulation to 200V, left upper, lower, and CN XI MEPs were obtained. MEPs from muscles of CNs VII and XII were obtained at 140V using C6-Cz stimulation on the left side and at 220V using C5-Cz stimulation on the right side. Baseline BAEPs revealed symmetric waveforms. There was no significant EMG activity noted in the cranial nerves monitored prior to first incision. 

 

The following neuromonitoring events occurred during tumor exposure and resection, and the surgeon was advised immediately as these changes took place:

-          EMG activity was seen in CNs VII, IX, XI, and XII during exposure and tumor resection (exact times are detailed in the neuromonitoring events logs).

-          At 10:44, there was an increase in latencies of waves IV/V complex with stable amplitudes, and further increase was observed at 10:53. Papaverine was given. By 11:13, wave IV/V amplitudes on the left side decreased about 50% with run-to-run variation.

-          At 11:00, there was a decrease in left CN XII MEPs, present at smaller amplitude.

-          Resection was completed at 11:25, and dura closure began. During closure, left BAER and left CN XII MEP recovered to acceptable baseline values. 

The amplitudes and latencies of SEPs from all limbs and MEPs from all muscles monitored were within acceptable baseline values at closing. EMG was quiet.