Corpus callosotomy might have reduced epileptic seizure-induced repetitive shoulder joint dislocation in two patients with medically intractable epilepsy who were not focus resection candidates

Introduction

Epileptic seizure has been reported to cause shoulder joint dislocation.¹ When a convulsing patient in a lateral decubitus position places their body weight on a fixed arm, the excessive force applied to the shoulder can result in dislocation.² This may lead to significant bone loss from the glenoid and humeral head, creating a situation in which repetitive shoulder dislocations may occur.³ Generally, procedures such as Bankart repair or the Bristow procedure are considered for the treatment of shoulder joint dislocation.^4,5 However, surgical strategies for shoulder joint dislocation require post-operative rehabilitation. In addition, these regimens require prevention of dislocation for a certain period of time.^6,7 Patients with medically refractory epilepsy and intellectual disability and/or autism are predicted to be uncooperative in terms of postoperative treatment. Moreover, intellectual disorder is one of the risk factors for surgical site infection.⁸ Surgical intervention for shoulder joint dislocation thus might not be a treatment option for such patients. Although many reports have described shoulder joint dislocation caused by epileptic seizures, little has been discussed regarding solutions.^2,9 As repetitive shoulder joint dislocations are considered to be underestimated,^2,3,10 patients with epilepsy may frequently experience shoulder joint dislocations with severe pain and visit emergency rooms on every occasion simply for manual repositioning. However, longer-term treatment options appear lacking for patients with epileptic seizure-induced shoulder joint dislocations who are not candidates for shoulder and focus resection surgeries.

Patients with generalized seizure could be candidates for corpus callosotomy (CC).¹¹ This procedure reduces generalized tonic-clonic seizures and might turn them into focal onset seizures.¹²

We encountered two patients with repetitive shoulder joint dislocation due to medically refractory bilateral tonic-clonic seizures (BTCS) who were not considered candidates for shoulder surgery due to possible postoperative uncooperativeness and frequent BTCS. We hypothesized that CC might reduce the frequency and intensity of BTCS along with the frequency of shoulder joint dislocations.

Case series

Case 1

Patient 1 was a 21-year-old, right-handed man with bilateral temporal lobe epilepsy, autism and intellectual disorder (Tanaka-Binet intelligence scale: 7 years 1 month old). He exhibited focal onset impaired awareness seizures (FIAS) and focal to BTCSs at 8 years old, both of which proved medically intractable (FIAS, 1/month; BTCS, 1/2–3 months). Electroencephalography (EEG) showed epileptiform discharges over bilateral temporal regions. Brain magnetic resonance imaging (MRI) showed no abnormalities except for relative atrophy for his age. He was currently on lacosamide (LCM) and levetiracetam (LEV). He had previously been administered topiramate, carbamazepine and lamotrigine. He had undergone vagus nerve stimulation therapy that had not prevented BTCS and had suffered frequent shoulder joint dislocations.

Case 2

Patient 2 was a 34-year-old, right-handed man with left multi-lobar epilepsy, autism and intellectual disorder (Tanaka-Binet intelligence scale, 5 years 10 months old) who exhibited BTCS at 29 years old. At first, since seizures were brief and appeared on an annual basis, he had not been on any medications. However, as seizures exacerbated in intensity and frequency, LEV was started. As seizures finally reached daily frequency, LCM was added. However, seizures were medically intractable, and he also had started exhibiting status epilepticus (SE). EEG for Patient 2 showed independent epileptiform discharges over bilateral frontal, temporal and parietal lobes, with a left predominance.

As seizures in both patients caused right shoulder dislocation every time, they had visited the emergency room for shoulder repositioning, sometimes requiring general anesthesia (Figure 1). Their orthopedic surgeons did not regard either patient as a candidate for shoulder surgery due to the relatively high frequency of seizures and likely uncooperativeness after shoulder surgery. Discussions regarding epilepsy surgery were held in our case conferences, where the patients were considered unsuitable for focus resection surgery due to the multiple foci and predicted uncooperativeness with invasive monitoring. To reduce BTCS in both patients and SE in Patient 2, we performed total CC for Patient 1 (Figure 2) and anterior callosotomy for Patient 2, as these procedures were considered to have the possibility of preventing shoulder dislocation. The reason for anterior callosotomy in Patient 2 was simply the preference of patient’s family, as they were concerned about the risks of disconnection syndrome.¹³ The etiology of epilepsy was unclear in both patients. However, as both were patients with autism spectrum disorder and epilepsy, shared underlying neurobiological mechanisms might have been involved,¹⁴ such as genetic issues¹⁵ or mammalian target of the rapamycin pathway.¹⁶

Figure 1 Shoulder dislocation in Patient 2. A normal glenoid cavity conforms to the red circle. The anterior edge of the glenoid cavity is straightened (white arrow) indicating bone defect, at the 2:00–6:00 position (A). The humeral head (yellow arrow) is displaced downward (B). The humeral head has been repositioned and returned to its original position (C).

Figure 2 MRI pre- and post-corpus callosotomy for Patient 1. Preoperative coronal (A), sagittal (B), postoperative coronal (C) and sagittal (D) MRI FLAIR of Patient 1.fi. The arrows show that the corpus callosum is totally removed (B and D).

Results

After the CC, FIAS remained in both patients, but BTCS became rare and SE disappeared in Patient 2, even though we did not change any medications post-operatively. Right after the callosotomy, intra-operative electrocorticography (ECoG) strip electrodes in bilateral frontal cortices showed reductions in epileptiform discharges for both patients. Generalized discharges were only seen in Patient 2, and were drastically reduced and lateralized to the left hemisphere (Figure 3). Clinically, seizure frequency and intensity were reduced, but seizure semiology itself did not change after the callosotomy. As of the time of writing, Patient 1 has experienced only three BTCS events with two shoulder joint dislocations within the 5 years after CC, whereas previously he had experienced shoulder dislocations once every 2–3 months. Patient 2 has experienced no BTCS for the 5 months since CC, although one spontaneous shoulder joint dislocation was seen within the same period; previously he had experienced shoulder dislocations 3–4 times/month (Table 1). Before CC, even though both patients had used shoulder-immobilizing braces, BTCSs had induced shoulder dislocation. After CC, immobilization therapy using shoulder immobilizer braces allowed each patient to maintain their shoulder in the correct position due to the reduced occurrence of BTCSs. Both were also able to perform range of motion and muscle-strengthening exercises, which required shoulder joint immobilization for at least several weeks. No neurological abnormalities were seen except for transient alien’s hand in Patient 1 and transient mutism in both patients.

Table 1 Clinical information and data between pre- and post-callosotomy

Figure 3 Electro Corticography (ECoG) of Pre- and post-corpus callosotomy for Patient 2. (A) Pre-corpus callosotomy ECoG monitoring from bilateral frontal lobe cortices shows generalized poly-spikes. (B) Post-corpus callosotomy ECoG shows reduced generalized poly-spikes lateralized to the left hemisphere. The epileptiform discharges on the right side are eleminated (arrow). As scalp EEG showed epileptiform discharges predominantly in the left hemisphere, we used an 8-contact strip on the left hemisphere and a 6-contact strip on the right hemisphere.

Discussion

As both patients obtained reductions in seizure frequency and intensity, the occurrence of shoulder joint dislocation was reduced. Patients with medically intractable epilepsy currently benefit from epilepsy focus resection surgery. However, if severe intellectual disorders are present, both epilepsy focus resection surgery and shoulder joint surgery may become much more difficult. These patients thus need to attend the emergency room for shoulder repositioning, which could reduce quality of life for both patients and caregivers. Shoulder joint dislocation caused by epileptic seizures is said to be underestimated.^2,3,10 Many patients suffer from shoulder joint dislocation due to frequent seizures without any treatments being suggested. For patients who are unsuitable for shoulder and focus resection surgeries and who suffer from frequent shoulder dislocation, CC could offer a good treatment of last resort.

Conclusion

For patients who are not candidates for focus resection or shoulder-repositioning surgeries and who are suffering from frequent shoulder dislocations, corpus callosotomy could represent a good last-resort treatment.