Paraparesis and left upper extremity weakness after total arch replacement with frozen elephant trunk: possible contributions of spinal cord ischaemia and cervical radiculopathy

Abstract

An 82-year-old man underwent total arch replacement with the frozen elephant trunk technique for an aortic arch aneurysm. Upon awakening 3 hours postoperatively, the patient exhibited flaccid paralysis of both lower extremities and left upper extremity weakness, whereas the right upper extremity was largely preserved. Cerebrospinal fluid drainage and blood pressure augmentation were initiated for suspected spinal cord ischemia. Lower-extremity motor function partially recovered, but left upper-extremity weakness persisted. Spinal magnetic resonance imaging demonstrated intramedullary T2 hyperintensity at T2/3 and bilateral neural foraminal stenosis from C3/4 to C6/7. Neurological examination revealed predominant weakness in the left C7 myotome with an absent left triceps reflexes, suggesting concomitant C7 radiculopathy. This case demonstrates that neurological deficits after aortic arch surgery may be multifactorial and highlights the value of detailed neurological examination and spinal imaging when upper extremity weakness is disproportionate.

Introduction

Total arch replacement using the frozen elephant trunk technique is a recognized treatment for complex aortic arch disease. While spinal cord injury typically presents as lower extremity paraplegia or paraparesis, disproportionate weakness in the upper extremity is rare. In this report, we discuss a case of postoperative bilateral lower extremity paralysis and weakness in the left upper extremity following total arch replacement. In this instance, thoracic spinal cord ischemia and possible cervical radiculopathy were considered as contributing factors.

Case report

An 82-year-old man had a 55-mm aortic arch aneurysm. His medical history included chronic kidney disease, hyperuricemia, and dyslipidemia. No preoperative motor deficit or gait disturbance was documented. Endotracheal intubation was uncomplicated, and excessive cervical extension was avoided.

Cardiopulmonary bypass was established with arterial cannulation of the ascending aorta and venous drainage from the superior and inferior venae cavae. Myocardial protection was achieved using retrograde cardioplegia. After cooling to a rectal temperature of 30°C, the ascending aorta was cross-clamped, and retrograde cerebral perfusion was initiated. The aorta was incised, and antegrade selective cerebral perfusion was added.

A hybrid prosthesis consisting of a 30-mm vascular graft and a 31-mm stent graft with a stent length of 90 mm was deployed using Frozenix 4B (Japan Lifeline, Tokyo, Japan). Lower-body perfusion was resumed after 28 minutes of circulatory arrest, and the left subclavian artery was reconstructed to a branch of the prosthetic graft. After completion of the proximal anastomosis, the remaining arch branches were reconstructed individually. The operative time was 192 minutes, and the cardiopulmonary bypass time was 111 minutes. The operation was completed without any remarkable intraoperative events.

After admission to the intensive care unit, the patient’s condition was stable, and the mean arterial pressure was maintained at ≥75 mmHg. He regained consciousness 3 hours postoperatively, at which time flaccid paralysis of both lower extremities and weakness of the left upper extremity were noted. Postoperative spinal cord ischemia was suspected, and cerebrospinal fluid drainage was performed for 3 days. Methylprednisolone was administered at 1000 mg/day for 3 days, and naloxone was administered at 1.2 mg/day for 2 days. In addition, blood transfusion and norepinephrine administration were performed as needed, with target hemoglobin concentrations and mean arterial pressure levels of ≥10 g/dL and ≥ 90 mmHg, respectively. The patient was extubated on postoperative day (POD) 1.

On POD 2, slight voluntary movement of both lower extremities was observed; however, weakness of the left upper extremity persisted. Neurological examination revealed no cranial nerve deficits, and both lower extremities could be elevated only briefly. Vibration sensation was mildly reduced in both upper extremities and severely impaired in both lower extremities. The Babinski reflex was absent bilaterally, whereas the Chaddock reflex and ankle clonus were present bilaterally.

Manual muscle testing of the upper extremities revealed the following grades (right/left): trapezius, 5/5; deltoid, 5/5−; biceps brachii, 5/5−; flexor carpi radialis, 5/5−; triceps brachii, 5/3−; extensor carpi radialis, 5/3−; extensor digitorum communis, 5/3; abductor digiti minimi, 4/4; dorsal interossei, 4/4; flexor pollicis longus, 5−/4; flexor digitorum profundus, 5−/4; and abductor pollicis brevis, 5/4. Thus, right upper extremity strength was largely preserved, whereas weakness was most prominent in muscles corresponding to the left C7 myotome. The right triceps reflex was diminished, and the left triceps reflex was absent. The biceps reflex was preserved on the right and diminished on the left, whereas the brachioradialis reflex was diminished bilaterally. Sensory examination revealed hypoesthesia over the proximal palm and dysesthesia over the proximal volar wrist, without apparent sensory abnormalities at the fingertips. Electromyography and nerve conduction studies were not performed.

Brain magnetic resonance imaging (MRI) revealed acute infarctions in the bilateral cerebellar hemispheres and right occipital lobe, with no acute lesions involving the motor cortex, corticospinal tract, or other relevant motor pathways.

On POD 6, spinal MRI revealed bilateral neural foraminal stenosis from C3/4 to C6/7 and intramedullary T2 hyperintensity at the T2/3 level (Fig. 1). Foraminal stenosis was most severe at C6/7 and greater on the left. These previously undocumented findings may represent incidental age-related degeneration. The distribution of weakness, absence of the left triceps reflex, and cervical foraminal stenosis suggested possible left C7 radiculopathy in addition to thoracic spinal cord ischemia.

Figure 1.

Spinal MRI on postoperative day 6. (a) Sagittal T2-weighted image showing intramedullary hyperintensity at the T2/3 level. (b) Axial T2-weighted cervical image at the C6/7 level showing neural foraminal stenosis. The arrow indicates the left neural foramen.

Computed tomography (CT) on POD 8 revealed that the distal end of the frozen elephant trunk was positioned at T4/5 (Fig. 2). On transfer to a rehabilitation hospital on POD 15, the patient could walk with minimal assistance, although left-hand weakness persisted.

Figure 2.

Postoperative contrast-enhanced CT. (a) Diagonal and (b) lateral three-dimensional reconstructions showing the distal end of the frozen elephant trunk at the T4/5 level.

Discussion

Spinal cord injury is a serious complication of aortic surgery. Risk factors after frozen elephant trunk repair include deep distal deployment, perioperative hypotension, diabetes, and severe atherosclerosis [1, 2]. In this case, bilateral lower-extremity flaccid paralysis, T2/3 intramedullary hyperintensity, and partial improvement after cerebrospinal fluid drainage and blood pressure augmentation supported spinal cord ischemia.

The T2/3 lesion and cerebral infarctions did not explain the persistent left upper-extremity weakness. C7-predominant weakness, an absent left triceps reflex, and cervical foraminal stenosis suggested possible C7 radiculopathy. However, the sensory distribution was atypical for C7 radiculopathy. Concomitant foraminal stenosis at adjacent cervical levels may have contributed to these sensory findings. Without spinal canal stenosis or cervical cord compression, cervical myelopathy could not be established.

Yamada et al. reported tetraplegia after frozen elephant trunk repair in patients with cervical canal stenosis and cord compression, suggesting increased vulnerability of the diseased cervical cord to perioperative injury [3]. Neurological injury after cervical hyperextension has also been reported in cervical spondylosis [4, 5]. Although neither excessive extension nor cord compression was present, foraminal stenosis may have predisposed the C7 root to perioperative injury; however, the mechanism remains uncertain.

Perioperative left brachial plexopathy from compression could not be excluded despite preoperative positioning checks. Clinical findings could not reliably distinguish it from C7 radiculopathy, and peripheral localization remained uncertain without electrophysiological testing.

Postoperative neurological deficits after aortic arch surgery may be multifactorial. Disproportionate or asymmetric upper-extremity weakness should prompt evaluation for causes beyond cerebral infarction and thoracic spinal cord ischemia. Serial neurological examinations and brain and spinal imaging aid anatomical localization and rehabilitation planning.

Conflicts of interest

The authors declare that they have no conflicts of interest.

Funding

No funding was received for this study.

Ethical approval

No ethical approval was required for this case report according to institutional policy.

Consent

Written informed consent was obtained from the patient for publication of this case report and accompanying images.

Guarantor

Tomoaki Ishihama, MD is guarantor.